New Directions

Our very good buddy, Mike Mathews, commented the other day that we haven’t put anything new on the old ‘Rocket Works’ blog. We’ve been very busy, but that’s no real excuse, so here’s an update:

It’s all change and new directions for the car. A cockpit cover is being made, the front running gear is being changed for different wheels, fatter tyres and bigger brakes. The rear suspension is being strengthened and an additional, very small, parachute is being added. The controls have been moved and the seat position changed to accommodate our new driver. Yes; you heard that right – a new (lady) driver! We made the decision, a few months ago to split engineering and driving duties. It was easier to replace the driver (not that easy, but easier!), so that’s what we’ve done. Her name is Joanna Finch and she’s a very bright and capable woman with a good understanding of engineering and a passion for going fast. (Her regular wheels are attached to a 950cc supermoto – ‘nuff said!).

Two further new members have joined the team, David Lowe an experienced Mechanical Engineer with a back-ground in Aviation and Aerodynamics and Jon London with a lot of experience in rocketry and in education.

David Lowe will be working on improving aerodynamics (including some wind-tunnel work) and making sure that our running-gear is up to the task ahead. Jon will be working both with the rockets and in our educational outreach activities. This takes a huge load off me (Carolynne), now if only someone else could drive the bus…..

We’ve also been doing a lot of work on other applications for our rocket systems. We have met with Professor George Fraser at the Space Research Centre at Leicester University. George is a very interesting man who makes me think of a Scottish version of Dick Keller, (understated, very funny, very commercial and very single minded). George gave us a jaw-dropping tour of his enterprise (and it is an enterprise – not an ivory tower) with room after room of wonderfully engineered stuff, all for the purpose of building payloads to go into space. There was so much neat stainless-steel stuff all over the place. (I should have taken a bigger handbag!).

The upshot of that is we’ve agreed to start on the process of a feasibility study, and then (hopefully) a development programme to do the work to provide a low-cost orbital insertion vehicle. Jon London (who’s passion is rockets for flight) will be in the thick of this process. Many, many thanks must go to Philippa Davies of De Montfort University, whose thoroughness and persistence made this all come together. I’m doing my best to ‘rope her in’ on a more long-term basis. We like having bright women on our team, we do!

I’ve been corresponding and Skyping with a very bright and experienced ex-pat engineer, Geoff Daly, who’s been a great mentor and sounding-board for the last couple of year or so. Geoff has great experience at the highest level in rocket engineering and has his own Consultancy based in New Hampshire in the USA. He’s been very helpful in sourcing up-graded components. He’s also been able to make some real headway in getting to the bottom of what happened in the Mojave Desert, three years ago, when three people were killed and several more injured in an N2O explosion during a test at the ‘Scaled Composites’ facility. His research has given us a lot of comfort, in that it has largely confirmed the conjecture about exactly what kind of event it was and where the mistakes were made. Our safety systems, design and methods have been developed to avoid such an event, so confirmation that we’re on the right path is very well received.

In the course of his efforts, Geoff has talked with many of his contacts and colleagues in the USA, who, it appears, have shown much enthusiasm for our designs, systems and safety methods. Geoff is still pressing on with these matters, so it’s premature to go into very much detail. However, consider this: Mid Afternoon, June, the Mojave Desert, no shade, concrete test-pad, N2O!! Our dear readers can work this one out for themselves, methinks. Keep up the good work, Geoff!

Oh! I forgot – Why all the changes to the car?

400 mph in the UK!!

There you go – I’ve blurted it out.

SECOND OPINION

The following is a short paper by Mark Stacey of Waipu, New Zealand. Mark is a polymath, Engineer, Chemist and Researcher who has worked on many prestigious projects from rocketry to electric vehicles. His is an opinion worthy of respect.



Nitrous oxide hybrid rocket with saturated wick fuel grain and free piston oxidizer tank.
Mark Stacey
Director, CNC Prototyping


Abstract:

A discussion of the many advantages of a hydrocarbon saturated wick feed combustible fuel grain combined with a pressurised piston driven liquid nitrous oxide oxidizer feed.

Introduction:

The use of self pressurising nitrous oxide oxidizer with solid fuel in hobby and commercial rockets is a well known and well developed process however development has plateaued with most development focused on refining the known, i.e. shaping the fuel grain, nozzle development, casing and tank design. This leaves fundamental problems, which have caused accidents and lower than optimum performance, unaddressed. The following describes the significant improvements that have been made to the basic nitrous oxide solid fuel design of rocket.

Oxidizer feed:

Nitrous oxide is a well understood industrial chemical and compared to many oxidizers has many advantages. It is relatively cheap, is relatively unaffected by contaminants, does not require cryogenic handling and is, compared to many other oxidizers, relatively stable. However since the 1930's industrial users have been aware that gaseous nitrous oxide is prone to detonation as temperature rises above ambient.

Most current hobby and commercial rocket motors heat the nitrous oxide to provide self-pressurisation thus putting the oxidizer system into an area where detonation is increasingly likely to occur if shocks or hot spots are present.

Additional problems are:
The density is reduced, so for the same tank volume, less mass of oxidiser is carried.
The tank must have a percentage of free gas space for the initial pressurizing.
Once the oxidiser is flowing, consistent pressure, and hence feed, is uncertain.
As the oxidiser level drops, the flow to the motor becomes a mix of liquid and gas, thereby reducing performance.
The tank always has some residual liquid and gas that is wasted which, in aerospace applications, reduces payload.

The tested solution developed to overcome these problems is a cylindrical oxidizer tank with a free moving piston. The piston is driven down the oxidiser tank by a pressurising gas. The advantages are the nitrous oxide is always liquid both during loading and firing, greatly enhancing operational safety and performance. When discharging to the motor the flow rate is even and the tank is completely emptied.

Fuel grain:

Various fuel grains have been used in nitrous oxide motors, but all previous grains have problems. Hard thermoset plastic grains require careful internal shaping for an optimum thrust profile and are prone to cracking and loss of sections of the grain. In the worse cases this can lead to nozzle blockage and casing failure. Alternative soft fuel grains, such as modified waxes or thermoplastics, allow some compensation for oxidiser flow variations but are prone to erosion with out combustion, reducing motor performance.

The use of a liquid hydrocarbon infused, self-wicking, combustible liner as the fuel grain, overcomes these problems and has additional advantages:

As the motor runs the liquid fuel evaporates from the liner cooling the outside of the liner and thus the case due to the latent heat of evaporation of the hydrocarbon.

The rapid evaporation causes turbulent mixing ensuring the fuel is burnt inside the motor casing.

The motor runs a constant thrust profile as only enough liquid hydro-carbon evaporates to react with the oxidizer flow.

A simple orifice on the oxidiser flow is all that is required for even and complete combustion characteristics.

The liner chosen as the wick is heavy density cardboard tubing. This provides a liner that erodes in a linear fashion for the complete length of the motor. Multiple firings have confirmed this behaviour. As the self ablating and insulating action leaves no hot spots it allows the use of an aluminium motor casing.

Conclusion:

The combined developments of a hydrocarbon saturated wick feed fuel grain, and a free piston liquid feed oxidizer, provide demonstrated safety and performance benefits to the liquid oxidizer solid fuel motor hybrid motor combination.

OPEN LETTER TO DAVID WILLETTS

Dear Mr. Willetts,

Having developed what many in the international world of Rocket engineering see as the best, most cost effective and most innovative Nitrous Oxide Rocket system on the planet, and one that is already producing spin-off technology with wider export potential, I decided to have look at what development support there may be in the East of England.

So I searched and searched for support in such categories as Mechanical Engineering and aerospace technology. On all the sites representing the various Government-funded agencies, form NGOs to Universities I found nothing that fit those categories, except for things aimed at big businesses.

If you’re a small operation, there is absolutely nothing out there.

Here we are, needing to develop high-end engineering capacity and to grow the small-business sector, (the largest sector for employment in the U.K.), and what do we find?
Nothing!

We’ve done more to get youngsters involved in engineering, by taking our rocket-powered car to schools and events aimed at young people, than most others. We recently took the car to the new Ormiston Victory Academy in Norwich, where one of the teachers reckons we inspired up to thirty youngsters to take a real interest in engineering as a career, in one day!

We have had agreements with two universities to work together to develop our technology. Both found it too much work and gave up before we could get started.

If the government wants to promote innovation, the last thing it should do is give development money to institutions and let them pick and choose. Development money has to follow the technology, not the system.

Universities are populated by people on tenure with so much ‘academic freedom’ they can behave as they like with no fear of consequences. Agencies are populated by people from big business who tend to structure their offerings around their own industrial experience. There is no room, or recognition, in this system for the small innovator.

Frank Whittle was a small innovator. Look what we did for him and his little innovation (the GAS Turbine Engine!). Ken Tyrrell took three F1 world championships for the UK, working from a woodshed. Small is beautiful, efficient and creative.

If you want to see what we have, please look at:
www.laffin-gas.com and follow all the links.

One of our spin-offs has world-wide export potential. This is technology we have built and made to work – not simply a nice idea needing money to check it out.

I would like to meet with you, or a senior member of your staff, to go through these issues.

We are true champions of technology education and development who are out there ‘doing’ without help or ‘push’ from any agency or institution. Maybe we are worth a listen?

Cheers

NADINE'S THE STAR!

What a great couple of days we have just spent at the most inspirational school! We were treated to smartly dressed, well-mannered students, (“Can I hold the door open for you Miss?”), great food and one class after another viewing the car and rocket technology asking great questions and showing real interest.

Much thanks must go to their own ‘Rocket Man’, science teacher Rod Stevenson, at whose initial invitation we had decided to attend. Rod’s enthusiasm, energy and commitment to his vocation really inspired us all to step up a gear and do some real teaching! Jon London was in his element, teaching and communicating with the students, and playing with rockets at the same time. Class after class came to see the car, which was on display in a nice toasty-warm building all day on Thursday. The day went by in a blur of activity and energy. I really do think we inspired up to thirty young people (male and female) to think more than seriously about engineering as their future career path.

Several students stood out for their brightness, intelligence and inquiring minds. We do, however, have to single out one very special girl for the finest effort and commitment on the day. The title of ‘Team Laffin-Gas Star of the School’ goes to Nadine Gage.

Nadine was just fascinated with the idea of rockets.

“Can it go to the moon?” she asked. I’d been telling the students all day that there was no such thing as a silly question and, considering Nadine’s age; this was a very good question indeed. We explained that the car was only designed to go a couple of miles at the most and asked her how far away she thought the moon was.

“About five thousand miles” was her answer. I told her that it was much further away than that and asked if she could go and find out exactly how far away the moon really is.

An hour or so later, Nadine was back with the answer. Not only in miles but also in kilometers and pointing out that this distance was, in fact an average. We were impressed. I decided to give her another challenge, namely to find out how far away the Sun is, and how long it takes for the light to get to Earth. I told her she might find out something about the speed of light in the process.

While I was busy with another class, Nadine returned, collared David and told him the correct distances in miles and kilometers and followed that up with the exact speed of light in both units!!

Nadine: You are a STAR!!

In the evening we took part in a Community event with plenty of food and a superb fireworks display in celebration of the creation of this utterly outstanding Academy. After the fireworks it was our turn. With the Head Girl on the button to light the pyrotechnic, Sixth-former Sam and ‘Rocket’ Rod Stevenson on the lanyards, Jon gave the count-down over the PA.

Under my direction, the sequence was cued, with each person doing their bit bang on time and the bio-diesel rocket burst into life with a display of smooth power that we have come to expect. Done!! A live-test firing of a truly serious rocket-motor in a SCHOOL!!

We hadn’t fired our maximum rocket, by any means, but it was still big, loud and proud!! What an honour to be the finale for such a great event!

As our adventure continues, we shall be carrying Ormiston Victory Academy’s logo on our car, and we are sure that this has been the birth of an exciting long-term educational and technological co-operation between the Academy and ourselves.

HUGE ROCKET TO BE FIRED AT SCHOOL OPENING DAY

When: Thursday 21st October 2010 7:30pm

Where: Ormiston Victory Academy, Norwich

The Laffin-gas Rocket Car team will be firing the biggest rocket ever to fired at a School.

Last Tuesday, we conducted a site inspection at the Ormiston Victory Academy to make preparation for the first public static firing of one of our Hybrid Rockets.

The Ormiston Victory Academy is an amazing new institution rising from the ‘ashes’ of Costessey High School in Norwich. We were greeted at the door by the Deputy Head and Rod Stevenson (a teacher at the school who is also a well-known person in the world of Rocketry). We were then treated to a quick tour of their engineering and technology facilities. At last: A school with lathes, milling machines, band saws, two forges, CNC equipment, a laser-cutter and so on! These tools weren’t sitting idly as ‘not safe enough to use’ but actually working, teaching and producing product!!

We met a few staff members and caught the infectious ambition and enthusiasm they all project. Is English Technical Education finally turning the corner and starting to produce the ‘hands-on’ engineers we so badly need? If this school is anything to judge by, the answer has to be a definite ‘YES’.

In an example of a spirit of ‘Education-Over-Caution’, the school approached us and not only asked us to bring our ‘Laffin-Gas’ Xperimental Hybrid Rocket Car to their Grand Opening Day, they also asked if we could FIRE one of our rockets for them. After agreeing on safety arrangements, and conducting a site visit to test the ground and ensure this can be done with a reasonable degree of safety, we have decided to go ahead.

At over 1,000lbs Thrust, this Nitrous Oxide and Bio-Diesel rocket will be far-and-away the largest rocket ever fired at a school, probably anywhere on the planet.

We’ve long been advocates of this kind of approach to technical education and we are delighted to have the honour of being part of this celebration of a truly ground breaking new school.


Contact: carolynnecampbell@gmail.com 01933 313816 (Rocket)
G.Howe@ormistonvictoryacademy.co.uk 01603 742310 x3438 (School)

OFF GOES THE TECHNOLOGY

David and I just finished watching the story of Burt Rutan’s ‘Spaceship One’, on Discovery Science. What a great story and what fabulous airframes and aerodynamic technology it all is. We couldn’t help but notice that the rocket was nothing like as impressive as the craft it was powering. The rocket exhaust was disorgainsed, it pulsed and its power output (for its size) was really not that impressive. On the succesful flight, at the end of the burn, the rocket seemed to be coming apart internally with visible hard debris being ejected.

For years now, Nitrous Hybrid rockets (the type of rocket used in 'Spaceship One') have been using a solid plastic or rubber fuel grain. The ‘grain’ is that part of the rocket that burns as fuel in the Nitrous Oxide. When we started out, that’s what we used, as it was a proven material for this application. These fuel grains had their drawbacks. They are dirty and smokey when they burn. They are hard to get lit and they rely on the available surface area of the inside of the tube to provide fuel for the burn. Folk at the drag-strip did not like the mess the rockets left behind.

So we decided to try a cardboard fuel grain as burning paper left much less mess behind. Unfortunately the cardboard absorbed so much moisture from the air that it did not give the needed power and reliability. One day, while taking a shower, I was thinking about how to keep the cardboard dry. It occurred to me that, if we soaked the cardboard in an oil, then it couldn’t take up moisture from the air. It turned out to be a major breakthrough. After a couple of tests, using rapeseed oil, we discovered that we could get more power and a steadier burn using about one third the amount of Nitrous oxide. Later we tried other oils, the most spectacular turning out to be kerosene. One of our six inch external diameter rockets produced over 1,500lbs of thrust, using less than 2lbs of N2O per second of burn. We have shared these results with many people in the rocket world expecting that these results would put an end to the faith in plastic and rubber as fuels.

So why is the oil-soaked cardboard so much better? Simply, the cardboard is now acting as a ‘wick’ allowing oil deep inside to boil out under pressure forcing oil vapour into the heart of the rocket. The result is that the surface are of the cardboard does not so much limit the power of the burn.

To a man (or woman) the rocket folk have ignored it and carry on with their plastic and rubber fuel grains.

The next major development we came up with is the piston accumulator. We use pressurized nitrogen to push the N2O into the rocket. This is always at a higher pressure than the boiling point on N2O on the day. Systems that use the self-pressurisng property of N2O, by allowing it to boil, thereby producing high-pressure vapour, have several inherent problems.

The first is that N2O in the form of gas is very dangerous stuff and can explode without an ignition source. The second is that it rarely boils fast enough to keep the ‘push pressure’ up and the rocket tends to pulse as pressures and back-pressures fluctuate. The Third is that the N2O boils in the feed-lines to the rocket, making the lines full of a compressible liquid/gas mixture, which causes further pulsing and makes even metering of N2O flow impossible.
We discovered that, as a result of horizontal acceleration, with vertical bottles in the car, the liquid N2O would slosh up the side of the bottle. The Nitrogen, would then find its way around the N2O causing the rocket to lose power and splutter. If we sloped the bottles to allow for the acceleration effect, the Nitrogen would find its way around the N2o as soon as we opened the main throttles.

The solution was to place a free-floating piston between the Nitrogen and the N2O. This prevents Nitrogen blow-by and makes the system impervious to acceleration or to the angle at which the bottles are mounted. Another benefit is that all the N2O can be used without any gas mixing as the bottle empties, making the use of the N2O much more efficient. An unexpected side-effect, was a significant increase in power for the same oxidizer/fuel ratios and flows.

Again, one would think that this development would have been eagerly embraced by users of Nitrous Hybrid Technology. No chance. ‘Very interesting, but we’ll keep on doing it the same old way.’

One wonders how it is, in such a supposedly advanced engineering culture as we have in the UK, that such advances can be simply ignored by so-called ‘experts’.

On reflection, this country has never embraced technological advancement easily or readily. We gave away Frank Whittle’s gas turbine to the Americans and the Russians, while cutting Whittle’s funding and ripping him off for an invention we did not value at the time.

We are not making unsupportable claims about an idea that has yet to be proven. We have the video and the hard experimental data. We have the best power-to-weight ratio N2O hybrid around with the most beautiful and steady flame you could wish to see. We have full throttle control. And it's very very low-cost to build and use. I have done something the armchair engineers and modelers haven't done. I've got into the car, and lit the rockets quite a few times, which is no small thing to do.

With all this in mind, and having failed to get any acknowledgement or recognition for these significant advances, we have decided to take our technology to the other side of the planet, where the imagination and sense of adventure is still strong enough for these technologies to be taken seriously and welcomed with open arms.

Your loss, Britain! We tried and you didn’t want to know.

STILL PLOUGHING ON

Long time no write!

Firstly, our website is down. We’ve had a dispute with our Hosting Service.

We are now making new hosting arrangements and will be re-designing our website, taking into account all the developments that have occurred over the last couple of years on the internet.

In the meantime, we are still here and still working!

David has manufactured a new prototype valve that goes inside the input end of the rocket in an attempt to prevent backfires on start-up. We’ve had a couple of incidents on hot days where back-shock from the idling rocket has destroyed a throttle valve. We are installing this in one rocket and we’ll be conducting a test to see if it has the desired effect. We have also developed a new purging procedure that should prevent any recurrences of the problem.

Attempts to co-operate with a couple of Universities have come to nought. We had been warned that this may well turn out to be a waste of time, and so it has been. All kinds of positive emails and undertakings were received, but when it came time to ‘DO’ we have been met with deafening silence.

We are not yet ready to give up on working with educational institutions and we are trying again with another college. Actual research and development of challenging engineering seems to be something these institutions can’t actually do. If we are ever to get youngsters interested in engineering and science, in the numbers needed by our economy, something has to change in education.

We know that youngsters love the car and the rockets and they rapidly engage in learning the moment they get near the car. Unfortunately the teachers don’t seem to want to be bothered.

We will be at Sywell Aerodrome in a couple of weeks to take part in their superb ‘Youth in Aviation’ event. We expect to be overwhelmed by bright young people who can’t get enough of this kind of stuff. We spent the event last year utterly bombarded all day.

BANG!!

On Sunday 25th July, at the ‘Ladies That Launch’ event at Shakespeare County Raceway, ‘Laffin-Gas’ suffered its first start-line incident.

We were there in support of the very first event dedicated to the women who take part in Drag Racing. We were also using the weekend as an opportunity to train our newest team member, John London, who comes from the world of rocketry and was having his first experience of the world of Drag Racing. As training had gone well on Saturday, we decided to go for a two-rocket run on Sunday, which turned out to be a lot hotter than forecast.

There was a very loud bang, and a lot of gas was released from the car. We exploded one of the four main-throttle valves on opening the main throttle. The debris from the exploding valve was caught by the ballistic protection we had built in around the throttle assembly. While the bang was loud and, therefore, very energetic, the damage was limited to the valve itself and the hoses immediately upstream. No damage was caused either to the rocket or the pressure-vessel. The burst-disc protecting the pressure-vessel was not ruptured, indicating that the energy was dissipated further downstream. No-one, (including myself) was at serious physical risk from this event, but it does require an explanation.

It was the same sort of thing that occasionally happens in any big Nitrous burning car, often resulting in bits of carb and manifold being ejected through the air-scoop on the bonnet. In fact it was nothing like that big! When our car is on the line, everything is so quiet- the bang really stands out. In other cars it gets masked by the roar of the engine.

When we returned to the pits, we invited Paul Satchel (Senior Scrutineer and member of the MSA Drag Racing Committee) to inspect the car. Paul was happy that the safety systems had done their job and that we had acted responsibly.

The explosion was a result of something called ‘Compression Shock’, which happened when very warm gas (it was a hot day), which had built up in the very small space between the safety shut-off and the throttle valve, was exposed to back-pressure from the idling rocket just as the throttle was opened. We were firing two rockets. The one with a safety valve that was tightly sealed, did not have this problem. The volume of gas that did explode was less than 20cc. That is a tiny volume for such a big concussion!

We have built chillers into our race transporter to ensure our gasses and liquids are cold when we fuel up. We use insulating blankets to keep things cold after fueling. We pre-pressurise with Nitrogen Gas to ensure that Nitrous in the vessels and lines is always in its liquid state. But Sunday was a hot day, and a very small amount of N2O in a small section of the system, turned to gas, and was not purged (as the rest of the system is) when the start-up valves were opened.

We have now devised a new protocol to ensure that this section of the system is purged immediately prior to launch. We will also employ a cooling method directly on the throttles in future.

Photo courtesy of Missb Fotos

Something for the Techies

We're looking for testing partners who have nitrous oxide bikes and cars to help to develop a new application of our Accumulator technology. Below is a short paper on the subject.

NITROUS OXIDE AND ITS USE IN ROCKETRY AND HIGH-PERFORMANCE PISTON ENGINES

Nitrous oxide has long been employed both as an oxidizer in various forms of rocket propulsion, and as a performance enhancer for internal combustion engines. Many internet sites and published documents represent N2O as a harmless substance that can be handled safely with a minimum of expertise. As such it is very popular with amateur rocket enthusiasts, drag racers and others interested in getting more horsepower out of engines.

Nitrous oxide is, in fact, quite a unique substance with its own special physical and chemical properties, Properties that should be fully understood by anyone handling and using it in rockets or engines. Under certain circumstances, nitrous Oxide can explode in a very violent manner without any apparent source of ignition or oxidant to fuel such an explosion. These circumstances can easily occur during transfer and actual use and can occur in apparently normal conditions.

The attraction of N2O is that it is a good source of free oxygen, and that it is relatively easy and safe to handle and store. At lower temperatures it is a stable compound that is not very reactive, if a little corrosive. As it gets warmer it becomes less stable and predictable. High temperatures are needed to ‘split’ N2O into its two component elements, Nitrogen and Oxygen. Once split, a gas mixture of two parts Nitrogen to one part Oxygen is formed. One can see that this mixture is much richer in oxygen than is air. In air just under 80% of the mixture is Nitrogen and just over 20% Oxygen, four parts Nitrogen to one part Oxygen. It’s that extra oxygen in N2O that makes rockets burn so well and gives the horsepower boost to piston engines.

The other attraction of N2O arises from its quirky physical properties. Normally stored under pressure as a liquid, it has a very high vapour-pressure that is commonly used to push the N2O out of its containing vessel either into a rocket or into an engine. This ‘self propelling’ characteristic removes the need for pumps or other devices to move large volumes of liquid very quickly. At 20 deg C, the vapour-pressure is 58.5 bar or 850 psi (pounds per square inch). Nitrous oxide is very temperature sensitive. The higher the temperature, the higher the vapour-pressure, and the opposite applies to lower temperatures. A chart is included that shows the relationship of temperature and pressure. At 36.4 deg C, N2O reaches its CRITICAL POINT, when it starts behaving strangely. At and above this temperature all the N2O in a vessel becomes gas. It also becomes much more reactive as it approaches this temperature and can be made to explode by the application of a compression force. By ’explode’ one means an exothermic chemical reaction that is a true chemical explosion- not just simply a sudden release of high pressure gas. This stuff can go off like Semtex when it is too warm.

The boiling point of a liquid is determined by the gas pressure it is subjected to. If you go up Everest and want to make a cup of tea, the tea won’t be very hot, because, at that altitude, the air pressure is so low the water boils before it gets hot enough to make a decent cup of tea. Nitrous oxide behaves the same way. The lower the pressure, the lower its boiling point will be and vice-versa. At 20 deg C, the gas pressure needed to prevent boiling is 58.5 bar (850 psi). The instant that pressure is dropped, the nitrous oxide boils. The gas pressure that has this effect is, in this case, not air, but gaseous N2O, this gas is the nitrous version of the steam given off by water.

When a valve is opened to allow a rapid discharge of liquid N2O the gas pressure in the container will drop suddenly. As soon as this occurs the liquid N2O boils. Just as with water, the boiling will produce N2O gas and that gas will help to slow the pressure reduction. The gas can only be produced at a rate that is governed by the surface area of the liquid and the scale of the pressure drop. Once a valve is opened to release liquid, the pressure in the container will lower. This pressure is unlikely to be steady as all the N2O in the system is now boiling. Pockets of gas are forming randomly throughout the entire volume of the liquid, making the liquid itself compressible and, therefore, ‘springy’.
This applies even to the liquid in the line leading to the engine it’s supplying. This makes the rate of delivery to the engine much less predictable. It also means that gas bubbles are shot into the engine.

In the ideal set-up, for either a rocket or a conventional petrol motor, we want to deliver liquid N2O at a controllable rate. This makes the engine much easier to tune and to get a smooth performance. One often sees nitrous-aided cars venting the nitrous system to remove gas that may have formed in the lines. Initially this will deliver gasless liquid, but only for an instant as the liquid begins to boil.

Rocket motors that employ the ‘boil-off’ method to propel the N2O into the rocket always seem to ‘pulse’. The exit flame is never steady. One suspects that the same effect will occur in a petrol engine. In a rocket this effect is exacerbated by the resulting rapid changes of pressure in the combustion chamber. The back –pressure on the incoming line will cause the boiling point to fluctuate rapidly, making the pulsing effect worse.
In petrol engines employing a valve ‘overlap’ the same will apply. It’s quite common for my friend, Steve Woods, (who refills nitrous bottles at the track for his customers) to find that the bottle is so pumped full of air (with a little petrol thrown in, no doubt) that he has to let the air out before he can pump in the N2O. Racers beware – a pressurized container with air, petrol and N2O inside is a pretty unstable and dangerous bit of kit. The warmer it is, the more bomb-like it becomes.

For an engine tuner, or a rocket engineer, predictability is the key to ultimate performance. The ideal N2O supply system would never boil. It would deliver a predictable stream of non-compressible liquid, just like a petrol injector. This makes calculation of mixes and power output much easier and far more reliable. From both a safety and performance point of view, it would also be ideal to keep the N2O cold. Fluid densities go up and instability goes down. In a boil-off system, racers often employ bottle heaters to raise temperature in order to increase the delivery of N2O. The same effect could more safely be obtained by making the plumbing allow more N2O through.

In a boil-off system, as the bottle empties, gas will actually start to push the liquid aside and go directly down the line. If you watch water leaving your kitchen sink, as it empties a hole appears in the centre of the draining water as the liquid spins (coriolis effect). The same will happen inside a pressurized N2O container, with a resulting huge drop-off in performance. The emptier the container gets – the bigger the hole for gas to go down. Many racers counteract this by having more liquid than they need for the run, ensuring that the levels never get too low.

There is another complication with boil off-systems that is known as ‘Slosh’. In horizontal motion, the liquid will slosh towards the rear of the vehicle, climbing up the side of the container, again allowing gas to bypass the liquid.

In larger rocket motors, some of the downsides of the boil-off method are overcome by filling the gas-space with Nitrogen gas at a much higher pressure than the vapour pressure of the N2O. This prevents boiling. Often an external reservoir of Nitrogen is attached to lower the rate of pressure-drop as the container empties its liquid. This does combat many of the downsides of the boil-off system, but by no means all. Slosh can still happen as can gas blow-by. Back pressure can still make the system pulse quite heavily and the higher pressures mean that even more N2O must be left behind to minimise the blow-by as the levels get low.

So pushing with Nitrogen solves some of the problem but not all. The system is still somewhat unpredictable and the performance curve will be all over the place.
The ideal would be to keep the gas away from the liquid but still exerting enough pressure to prevent boiling. This is known as positive displacement. Gas/liquid shock-absorbers employ this technique. Either a bladder or a piston is used to keep the two separated. The gas acts as a spring damper, smoothing out pulses but the liquid remains free of bubbles and acts in a predictable manner. These shock- absorbers are more properly called ‘Accumulators’. We’ve tried bladders in our rocket-motor tanks, but they just weren’t up to the rigours of the high pressures. It is possible to buy ready-made bladder accumulators, but they cost a fortune, have materials compatibility problems and they are much too heavy for racing and rocketry.

So we tried putting free-floating pistons inside cylindrical vessels, Nitrous on one side, Nitrogen on the other. Now there can be no slosh, and no blow-by. The piston/gas arrangement also acts as a damper, minimizing the effect of back-pressure coming up the line. If the Nitrogen pressure is kept high enough there will be no boiling. The result was a very smooth and predictable rocket performance. We can stay well away from the Critical Point, vastly improving the safety aspects of the operation. In fact, the colder it is, the better it works.

Piston accumulators work very well for Rockets and we see no reason why the same shouldn’t turn out to be true for piston engines. All a tuner needs is predictability – then the rest is much easier.

Rained Off!!

Saturday didn't happen. Rain in the morning and a lousy forecast meant that we called off the trip to Bruntingthorpe. Just can't run in the wet!

Pending clearance from the track, we'll try again at Shakespeare County Raceway in two weeks' time. 12th & 13th June.

The Next Few Weeks

This coming Saturday, 29th May, we're puuting the car on display as part of the Rushden Power Fest, organised by Santa Pod Raceway. We're taking the opportunity to show our neighbours in the town waht has been built and engineered right here. Should be interesting...

On the 29th, we're off to Bruntingthorpe, a large active airstrip in Leicestershire, for a four-rocket running test. The runway is two miles long and very very wide, so it's a relatively safe environment for checking out handling and stopping. We'll be running bio-fuel rockets, not kerosene, as we really don't want all of that power for this test.

We have a few new team members, our fuelling supremo, David Rose can't make it, so we'll be going slow and steady to avoid any possible errors. The chillers are up and runnning. So, if it's a hot day, we should be able to keep the temperatures in the car well down into the safety zone.

Dave Burditt, from Datron Technology, is comiing up middle of next week, to install GPS and other data recording equipment. For the first time we'll be able to collect hard data on exactly what the car and rockets are doing in the real world.

Nerves are already starting to jangle... so slow and steady is the order of the day.

David has been a very busy boy. We've wanted to put brakes on the front for a while, and now it's been done. Putting brakes on wheels that were not designed for brakes is no easy matter. We've put on quite small twin, opposed-pot motorcycle brakes. The front tyres are too skinny for anything more. They will help with stopping and especially holding the car still when the rockets first fire up.

We've added a big chiller unit to the transporter, so now we can chill both the gases and the car itself. The colder it all is the better it runs and the safer the operation is.

We've also added more ballistic protection around the throttle area and under my backside.

That's just about all the jobs we wanted to get done before we take her out for a full four-rocket burn. As this is being written, we're trying to organise a date and location to be able to have the best crew available for a a private test,

We haven't yet decided which fuel combination we are going to run. The kerosene rocket has so much power, we may have to work up to running four of those.

So, sometime, in the next month, we'll see what she can really do!!

Fingers and toes crossed!

Rocket Analysis

David and I dismantled the Kerosene rocket yesterday, and (as usual) cut the fuel grain along its length.

Having given every component a thorough check we can report:

No damage, blistering or heat effect was observed on any of the metal parts of the rocket.

The fuel grain had burned evenly along almost its entire length. The inner liner was only half consumed (which is less burning of cardboard than any previous rocket).

If you watch the video carefully you'll see the rocket shut down very quickly - this is because the movement caused the safety solenoid to shut down. I must emphasise that nobody was put in harm's way.

Someone, posing as Tog from Eurodragster, made some very disparaging comments on Youtube. We know who this person is, he has been conducting a very sad hate campaign for several years. The comments have been removed.

Conclusion: A very repeatable rocket!!

Rocket Test Friday 19th March 2010

Angus, the farmer, has got out of the pig-breeding business. He’s been very busy tidying up the old place and our old testing site has been ploughed up, in readiness for a new Skeet shooting facility.

Angus very kindly moved us to the old muck-heap. That’s not so bad as it sounds as it’s a huge concreted area well away from anything we could damage, and almost all the muck is long gone. The only problem was – how to secure the testing-rig on a concrete surface? Angus came to the rescue by placing a huge old piece of agricultural equipment on the concrete using his great big front-loader. Basically a very heavy steel construction, with a fairly open framework, it was ideal for strapping our rig to it. We tried shifting the thing – it was going nowhere. ‘There’s no way one rocket is going to move this’, we observed.

In the morning we got everything ready, rocket, piston accumulator, and all the bits needed to fuel-up and fire the beast. Dave Rose, long-time team member and next-door neighbour turned up straight after work, about 3:00pm, along with Fred Thomas and Dave Burditt. Dave works at Datron Technology and he wanted to observe a test so that he can provide instrumentation for accurate data recording at future tests.

Dave Rose and I fuelled the rig up using our (now standard) protocol and got the bus and all the cars well out of harm’s way. Cameras were set rolling and I made the circuit to set off the pyro. I retreated to what I believed to be a safe distance and position, and pulled on the lanyard to open the pilot N2O valve. The rocket sprang into life. I couldn’t see the flame from my position, so I judged, by the sound, that she was well lit. One firm tug and the main throttle was opened. Loud, it was –very loud. ‘That’s going well’ I thought then I saw the whole steel framework starting to spin clockwise towards me. Carolynne exited stage-left at speed.

The rocket burned for just over five seconds with a very strong and steady exhaust jet. It was far and away the most powerful rocket we’ve yet fired. On reviewing the video, we could clearly see the shockwaves projecting from the bright heart of the flame. Four big and heavy men then tried to apply the same force the rocket had applied to the steel structure –they couldn’t budge it! We estimate that it took in excess of 1300lbs of thrust to do what that rocket did. I think we’re going to need more brakes in the car!!

The rocket itself was perfectly intact at the end of the burn, a little warm to the touch – but not hot.

For those of you who like the hard facts:

We wanted to run fully converted Bio-Diesel, but had an availability problem, so we soaked the cardboard with Kerosene, which is almost identical in terms of calorific value and volatility. The rocket had absorbed a little over 2 litres of kerosene.
We did not use an external Nitrogen tank. For the purpose of this firing, the Nitrogen capacity of the accumulator alone was more than adequate. We pumped in 8lbs of Nitrous oxide and pressurized to 1,000psi with Nitrogen.

Ambient temperature was 11.5 deg C, which gave us excellent fluid density in the N2O.

The burn duration was five seconds. All N2O was exhausted, the final pressure in the accumulator was 700psi (50 lbs over the vapour pressure of the N2O).

Now it’s getting very close to the time for getting out on the track and letting her rip!! We have the reliability and we have more power than we can safely use – so it’s time to learn how to get her stopped!!

VIDEOS NOW POSTED!

DOINGS IN THE OFF-SEASON

After an unusually mild November, when we were able to get a lot done in the workshop and the yard, the winter came in hard.

Where is Global Warming when you need it?

The off-season is the time for planning and preparation for the season to come. So we've not been idle. We've started serious design work on the new car, which we know will need outside money to get built. That means 'laffin-gas' needs to really perform for us this year. Testing on the piston accumulators is now complete, and we know that the blow-through problems are behind us. We've fired a total of five rockets with the new system and they've worked every time. High winds, and then cold weather prevented us from performing a full rolling four-rocket test, so we have to do that (hopefully at Sywell) as soon as the weather will allow. We are aiming to do this is mid-April. Then it's off to the track for a few runs to get her up to serious speed and do the testing on getting her stopped reliably.

'Laffin-gas' is more than powerful enough, and burns for long enough, to be as much car as you'd want to run on a drag-strip. So why build another car? Well, if we'd known what we know now, 'laffin-gas' would look very different. After all, she was always an experimental car. Now we want to take all that we've learned and apply that to the definitive Nitrous Hybrid Rocket Car. Brother Bob Campbell very kindly donated a pristine Reynard carbon-fibre Champ Car chassis (known in the trade as a 'Tub'. It's very very strong and makes an ideal safety-cell for a rocket-powered car. We always wanted to build in carbon-fibre, but we went for the traditional drag-racing cromolly-steel space-frame, to comply with drag racing regulations. As the new car will not be primarily designed for the drag-strip, it's time to go to carbon-fibre. The back chassis will still be of steel space frame construction, for ease of mounting rocket systems and running gear. We've put up a Facebook page called 'fans of laffin gas' so you can follow the design progress and get involved in solving the problems the project throws up.

We took a long look at what would be the realistic limit for what could be done on the possible available straight-line venues in the UK. Going fast and stopping does require a lot of room. The faster you can get up to speed, the more space you have left to get the car stopped. So to go really quick, you need big acceleration. We want the new car to go really quick. How quick? Well, getting the media interested in speed requires a number that can fire the public's imagination. That means either the speed of sound - out of our league, and out of the question in the UK. 1,000mph, which is the target for 'Bloodhound' and a couple of other builders in Australia and the USA, is the next step from a world publicity point of view. There's only a couple of places on the planet where that can be done. Trotting around the world with a rocket car is a very expensive and dodgy business. so we have to stay in the U.K.. So how fast do we need to go, to do something truly noteworthy, and not leave the UK? We reckon the answer is 400 mph. That's way faster than any wheeled vehicle has ever gone in this country. It would set a mark that would be very difficult to beat. It's also a very very difficult and potentially dangerous thing to do.

We've figured out that, with our rocket technology, we would need six rockets in a car that weighs about the same as 'laffin-gas' and a burn-duration of around twelve seconds to average that speed over a measured 1/4 mile. (That's the established distance for a British Record.) Each rocket will have to be supplied by an accumulator capable of holding enough N2O and nitrogen for the burn. The accumulators (which we will construct) will each have to be two metres long. With the piston design, they can lie horizontally in the back-chassis. With the rockets and all the systems to fit in, and a much shorter front chassis, the new car would be exactly the same length as 'laffin-gas', which is handy - because we can fit that in the bus.

It's very early days on this new project. Without serious sponsorship, we won't be able to do it, and even then it's a big and very ambitious task.. There will be many out there who will have a good laugh at us for even thinking about it - but we're going to have a go. In the meantime, 'laffin-gas' has a lot to accomplish.

In co-operation with Herts. University and Datron Technology, we'll be doing a series of single-rocket static tests with slightly varying set-ups during March. For the first time we'll be able to collect really accurate data on rocket performance, and this will allow us to select the set-up that we'll use this year.

We've been working on the transporter, doing a big re-wiring job on the old girl (which has been a real pig in the cold weather!). We are also going to put a big chiller on her, to allow us to cool the entire car down to ideal operating and fuelling temperatures.

We'll post reports on our progress as things get done.

New Begining

At last, we can begin to start afresh with all the laffin-gas webstuff.

From now on, all new info, updates and adventures will be posted here.

All the archive history follows...

HERTFORDSHIRE UNIVERSITY VISIT

It’s always amazing how it pays off to get out and about with the car. Going to events and shows where the car is on static display give us a chance to chin-wag with the public while we’re not in the middle of all the challenges of actually running her. When I’m about to get in the car, I’m usually not in the mood to be chatting with members of the public.

Static shows always turn up interest from knowledgeable and well connected people as well as the many many youngsters who just want to get close to a rocket and ask as many questions as we can answer. David usually spends most of the day getting youngsters in and out of the car, so that they can have the experience of feeling what it’s like to sit in such a crazy piece of kit.

On Wednesday we took the car to the University of Hertfordshire at the request of Ray Wilkinson, a senior lecturer at the School of Automotive Engineering. Ray also runs their Rocket Labs, which I think must be unique in the UK. We met Ray earlier in the year while we were at the Rockets and Space event at Waltham Abbey. One thing leads to another…

As soon as we pulled up in the Transporter, students appeared, which was very handy, as we immediately roped them in to help with unloading the car, extra rockets and components and all the other stuff we had brought to be examined.

What a bright, entertaining and invigorating group of enthusiastic young people! We didn’t stop all day, answering questions, explaining systems, taking useful comments and observations on board. There was a steady stream of folk getting in and out of the car, operating the controls and getting pictures taken.

The great thing was the fact that Automotive, Engineering and Rocketry students and Staff all got involved. This meant every aspect of the car, rockets, systems, chassis, running gear, aerodynamics, were all the subject of very knowledgeable discussion. The students weren’t the only ones in learning mode – there was quite a bit of very useful input that will be most helpful.

Ray took us both on a tour of some of the facilities at the University. For a couple of back-yard builders with a small machine shop and what seemed like loads of tools and equipment, it was like being in the ultimate toy-shop. Two wind tunnels, massive autoclave, lovely CNC machine-shop, professional standard Rocket testing equipment, materials stress labs, the list of great kit seemed endless.

We had taken our test rig and various rocket components, including one of our High Pressure Accumulators, so that Ray and his students could test our rocket systems under laboratory conditions. We discussed the possibilities of a series of development tests exploring variables of fuel types and oxidiser flows. Hopefully, Ray will be able to work this in with his regular teaching programme. It would be of tremendous help to us.

We also discussed the possibility of a co-operation in designing and building the next car. David and I have already started on this project, but it is very much in its infancy, so it’s a perfect time to get others involved. The new car is going to be built around a pristine carbon-fibre Champ-Car tub, which is already sitting in our workshop. We want to get away from traditional dragster space-frame construction and move on the composites for the entire chassis. The car will look very different to ‘laffin-gas’, with the cockpit much further forward, a much longer and lower rear section, F1 style running gear (modified for straight-line application) and six rockets. This car will capitalise on all the lessons learned from ‘laffin-gas’ (which has always been an experimental test-bed) and take the Hybrid Rocket Car to a new level. As systems have been developed and evolved, it is now obvious that, to get the most out of the technology, it’s time to design from scratch using all the data that ‘laffin-gas’ has generated. This doesn’t mean the end of ‘laffin-gas’, however, as we still want to show her true capability and keep on developing her potential.

A six-rocket car is probably a bit much for use on the ordinary drag strip. The new car will be run on longer tracks (airstrips) and be going after variety of performance records. We are presently in discussion with Ray and his colleagues to see how we can co-operate in this new adventure. Watch this space!!

NEW ROCKET-CAR WORLD RECORD

A few months ago, a guy called Tony Lovering got in touch. He wanted to build a rocket-powered radio-controlled model car and was interested in using Nitrous Hybrid technology. He wanted to know if we would be willing to give him some tips to help him on his way. After a good conversation on the phone, we invited Tony to come and see our car and we offered to share the things we had learned and developed for the full-sized manned car that we operate. Tony arrived and we went over the whole project, showing Tony all the bits and pieces involved.

Yesterday, Sunday 13th September, Tony ran his Hybrid Rocket powered car, ‘BLACK KNIGHT’ at the ROSSA UK Speed Championships, held at Shakespeare County Raceway.
(ROSSA: Radio Operated Scale Speed Association).

The ‘BLACK KNIGHT’ achieved a terminal speed of 163.58mph! Rocket powered cars represent a new class for ROSSA, but, having reviewed the ROSSA records, this represents a NEW OUTRIGHT WORLD RECORD for any radio controlled scale vehicle!

We say to Tony: ‘Bloody Well Done’.

Over the months, Tony has been building a single rocket, scaled-down version of our rockets and piston accumulator technology, with a series of trials and tests taking place along the way. After each test, we discussed the results and tried to help out by imparting what we know. Tony had a few failures, but he learned from each test, and his perseverance paid off last Saturday with a spectacular run.

The video of that run can be seen on YouTube at http://www.youtube.com/watch?v=RYujWn9WNXQ

Tony very kindly sent us an email on the same day:

Thanks for all your help. As you can see from the video there is much more to come

Thanks again

Tony

Tony, you’re very welcome.

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10/09/09

12:02:26 pm, by carolynne , 420 words, 10 views
Categories: Day to day

FRANKENSTEIN OPERATES!

This weekend (Saturday 12th September), the car will be on display at Sywell in support of ‘Young Aviators’ Day’. As it has always been part of our mission to get young people interested in engineering and related stuff, we are very happy to be taking part

For over two years, I’ve been threatening to cut the car in half! As our understanding has developed and systems have evolved, the space around the throttles and valves in the chassis has become very crowded. After the last test, we stripped out most of those systems for a general overhaul and clean-up. With rockets out and the chassis sitting bare, we decided that the time for radical surgery had arrived.

The plan was to add half a metre to the area of the chassis where all the ‘worky-bits’ are situated. With the car on stands, leveled and ready, David picked up the cutting tool and prepared to go for it. At that moment, there was a bright flash of lightening and an instant, shattering clap of thunder – no really - a big thunderstorm kicked off right overhead! Apocalyptic eh?

We’ve put in a new triangulated section of chromolly steel, adding just under half a metre. John Shakeshaft brought his mobile equipment and tig-welded the whole thing back together as strong as ever.

Then we had to replace or extend all the control connections, as everything was now too short. Throttle cables, electrical connections, ‘chute cables, brake lines all had to be done. Suffice to say, the job is finished and she’s back in one piece, looking a lot longer!

The extra space has allowed us to re-position the pressure vessels much lower in the chassis, adding to stability and safety and greatly improving the general looks of the car.

Geoff Caswell of ‘Caswell Engineering’ and ‘Flexrite/Chemgine’ is supplying us with all new stainless and PTFE double-braided hosing and connections as well as other 316 stainless fittings to improve the flows and safety of the systems. This is a huge help, as these are the absolute best you can get, and the most expensive!

A rumour has circulated back to us (as they always eventually do) that we blew up a rocket at our last test. We didn’t. In fact we damaged nothing of any importance as the safety systems did the job they were designed to do.

As soon as the new kit from CASWELL is in the car, we’ll be back out. I'll keep you all posted.

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20/08/09

12:44:31 pm, by carolynne , 453 words, 18 views
Categories: Day to day

SECOND SYWELL TEST

I’m writing this while everything is fresh in my mind.

What a fantastic day of testing at Sywell Aerodrome. We have so much to thank Michael Bletsoe-Brown and all the crew at Sywell for making the most fabulous facility available for our tests. We owe Sywell big-time, and we will definitely repay the debt with a super performance on that great runway.

The plan had been to test one rocket first –if all went well with that one – we’d fire three. As with most experimental projects, the plan changed as we went along. I made an error, misreading a pressure gauge, during the first fueling exercise. The result was that we got gas under the piston in the supply accumulator, and the rocket quenched on opening the main throttle.

Back to the old bus we went, and we decided to repeat the single rocket test, this time wearing my reading glasses!! She fired beautifully on the one rocket with mutli-dancing diamonds on view in the exhaust jet. Success!! The new cooling set-up had worked on what turned out to be the hottest day of the year.

We had two rockets left un-fired in the car, so we decided to fuel them both up and see how she went. One was pressurised to 950psi and one to 1,000psi, just to get a variable we could observe. The first rocket fired beautifully, the second underwent pressure-shock in the hoses and valves in the input side of the rocket, damaging an expensive valve and blowing out the ‘Fike’ burst-disc on the output of the accumulator. On hearing the bang, I lifted my foot and the car shut down safely. Thank you Fike! The explosion protection did its job. The rocket and accumulator were both perfectly intact. And we have found the pressure-shock threshold for a Nitrous Hybrid using piston accumulators. It’s 950 psi. Anyone planning on using this set-up, whether in models, or on a larger scale, please take note!! This is serious safety information that should be taken very seriously.

We now know that all our systems are working as designed, that we can do this in silly-hot conditions, and we can do it safely!

The car (once we’ve fixed the slight damage) is now ready to do her stuff.

After over four years of build and development of a novel technology, we are there. I can’t tell you how good that feels.

It must be beer o’clock!

PS We've had a chance to do some more analysis of exactly what occured. Any one who wants the low-down on the mechanics of the compression-shock event should contact Carolynne via the website remebering to put your email address in your email.

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19/07/09

05:38:58 am, by carolynne , 782 words, 23 views
Categories: Day to day

Testing in Heaven

Friday’s weather forecast was, to say the very least, not good.

Michael Bletsoe-Brown had very kindly allowed us to arrange a private test on the new concrete runway at Sywell. He’d had the track swept, two of our team members had taken holiday days off work, and commitments had been made. Under any other circumstances, we would have canceled the test as thunderstorms and high winds were predicted.

As this was a purely a systems test and not an attempt to go for a quick run, it made sense to see what we could get done.

We got to Sywell a little after nine in the morning and got the chiller running to get ready for fuelling. While the Nitrous was getting cold we walked the runway to have a close look and pick up any debris. We found a few small flint-stones, but, apart from that, the surface was perfect. We put out distance makers at 330yds and 440yds.

The original plan had been give her a good hard burn and shut off at 1,000ft. The wicked cross-wind ruled that out. In fact it did us a favour by making us really concentrate on the systems testing. So we went for plan ‘B’, which was to get her going and for me to play with the throttle to see how much control we had and how quickly the rockets would cycle.

This was the first time we would run rockets with chilled Nitrous. Watching the weather radar, we decided to start fuelling just before noon. What a difference having cold gasses! We were able to get much of the fuel in by gravity pour and, when the pump was needed, the pumping went steady and reliable. It’s still hard work having to pump against the pre-filled nitrogen, but safety really requires that we do it this way.

When we were ready, we rolled her on to the runway and let the folks at Sywell know we were ready to test, so that they could observe. Sywell’s crash tender was on the spot, fully crewed. We had a quick discussion to go over the safety info we had previously provided, and all was ready.

I got strapped in and Fred gave the radio instructions. She fired quickly on the pilot nitrous, which ran for two seconds, and I went to the main throttle. She blew out. We just didn’t get enough heat in the rockets.

We’d brought spare rockets, so we decided to swap the rockets out and have another go, as there was still plenty of fuel in the car.

An hour later, we ready to test again. This time we decided to let the pilots burn for four seconds and open the main throttles very gently to get her burning. This time she lit – but not really well, I backed the main throttles off and had another go and she hooked up, gave a good blast that gave me a kick in the pants, and then the fuel was gone.

We got the car back to the transporter, the sky darkened and the heavens opened with a spectacular thunderstorm. Luck was with us this time!!

We’d accomplished everything we wanted from the test. We’d learned that the increased liquid density of the chilled nitrous meant we were struggling to deliver enough start-up gas (not hard to fix!), we’d got her to burn well when we tried again, and we’d proven out the chilling and fuelling method.

What was really great was the totally relaxed atmosphere of a proper private test, where there was no pressure to perform for the public. No start-time to meet, no performance anxiety. It was just like static testing down at the farm with the added ability to get her in motion.

We’d also made some great new friends at Sywell. Michael Bletsoe-Brown enjoyed observing what we were doing and has invited us back to test again, basically until we are ready and happy to do a proper high-speed run on that marvelous runway.

The team met up in the bar at the ‘Aviator’ (what luxury – a pint of ‘Pride’, lovely surroundings and seating that swallows you whole) and we did our usual de-brief. As the only variable we had changed, was the chilling of the gasses, the conclusion was to increase the pilot volume by enlarging the inputs to get the rockets hotter more quickly.

Many, many thanks must go to Michael Bletsoe-Brown and his people at Sywell. My only regret is that we had had to go through the last couple of years without the use of such a brilliant place to test.

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06/07/09

10:28:49 pm, by carolynne , 802 words, 25 views
Categories: Day to day

Rockets, Rockets and More Rockets

Our visit to the Royal Gunpowder Mills, to take part in their ‘Rockets and Space Weekend’ was a great experience. What a great site, beautiful setting, fantastic history and a superb permanent rocket collection that is a must-see. A big ‘thanks’ must go to Lynne and all her people for putting on such an excellent event. For the first time in the life of our project we were able to mix and talk with a group of rocket experts and enthusiasts and actually felt part of that community. There were many knowledgeable people with backgrounds in military and civilian rocketry and many, many enthusiastic amateurs and modelers. We had a chance to get a close-up look at lots of different types of rockets and we listened to many differing theories and opinions – many of them at odds with one another, and all equally convinced of the correctness of their own positions. Yes, we learnt much.

We got to see the designs, models and actual rocket parts of the HTHP hybrid destined for the ‘Bloodhound’ LSR car and many of the different small-scale hybrids that are being flown by professionals and amateurs.

We think we were, on the whole, well received. Though we don’t know what was said when we weren’t in listening range! Our piston accumulators, our four rocket system and our bio-fuel ‘wick’ fuel grain were all very novel to the community. It would appear that we have done quite a few things that are truly innovative and have advanced the possibilities of ‘hybrid’ rockets.

One thing that did stand out is the undeniable reality of what we are doing. The car isn’t just a ‘design’ or a ‘plan’ or a graphic artist’s idea of what it’s all going to be one day. Our car was there – real, with tyres you can kick, rockets you can touch, tests and runs you can see on Youtube. The other thing that made us different is that ours is a manned rocket with all the safety implications and harsh realities of being a piloted vehicle carrying human cargo! As far as we can tell, it’s also the most powerful rocket car presently actually running and being used anywhere on the planet. If this isn’t the case, I’ll happily withdraw that statement. But as far as we honestly know, our project is unique. It’s also one of the most powerful hybrid rocket set-ups around.

We were offered testing facilities and various forms of technical assistance that will be very useful. The rocket professionals all seemed to be of the opinion that we were doing things well and with proper regard to safe operation, ‘though none of them expressed a wish to have a drive in her!

Last week we met with Michael Bletsoe-Brown of Sywell airport, right here in Northants, with a view to possibly testing on their new 1300metre concrete runway. We had brought the car along for the people at Sywell to have a good look for themselves. We parked the bus on the apron and got the car out onto the concrete so all could have a good look. We had arrived on a day when the British Aerobatics Team were practicing, so we were surrounded by a bevy of very powerful little aeroplanes and a bunch of crazy pilots – rockets are right up their alley!!

Michael very kindly arranged for me to inspect the new runway. It is a work of art! With special ballast in the mix, it has no need for large expansion joints and has been laid with amazing precision. The result is a wide, smooth surface that is ideal for high-speed testing. We have yet to arrange precise times, but suffice to say, our dream of having a private testing facility has now come true. I hope to have further talks with Michael later this week, to make firm arrangements and also to see what we can do to help promote what is probably the finest general aviation airport in Europe.

David and I have always liked Sywell, with its fabulous art-deco architecture and it’s amazing history, and we have donated a few artifacts to it’s aviation museum. So we are delighted to be able to be associated with such a jewel of a place.

The new refrigeration unit has now been tested successfully, and we can now get our gases down to less than 10deg C in a couple of hours. That solves our warm-weather fuelling problems. So now we’re ready for the next test run. It will either be at Sywell, in the next couple of weeks, or at good old Shakey at their Mini Festival this coming weekend (11th/12th July). We’ll keep you all posted on that.

The adventure continues…..

BE THE BULLDOG!!

After the last newsletter, where I talked about struggling with high ambient temperatures, we received two emails, one from Dick Keller (which was most inspirational) and one from Knut Soderquist, (which was typically to the point).

Dick told us to develop counter-measures and ‘Be the Bulldog!!’, while Knut told us that we had to deal with the heat as the show must be able to go on regardless of the prevailing conditions.

We’ve been told! (Again).

We’ve welded a very sturdy structure into the transporter to carry the gas cylinders, enclosed it, insulated it, and included a chiller, with the cold air ducted over the bottles and re-circulated inside the cabinet. We now have a secure and safe refrigerator for the gas and N2O.

Now we’ve got pistons in the car’s pressure vessels, we have to bear the safety aspects very much in mind. Dropping a piston at pressure on top of N2O gas is a very dodgy thing to do. So we have to pressurise the Nitrogen side first with enough pressure to keep the N2O liquid as it goes in. The hotter the day (and, therefore, the hotter the N2O) – the higher is the required pressure. The strain put on the pump and compressor can just get to be too much.

We can now chill the N2O (and the Nitrogen) to near freezing, which deals with this problem.

We’ve also put in a more powerful gas-ram to operate the start-up N2O system.

So now it’s time to test again at the track. That will be in the next two or three weeks.

In the meantime, we’re taking the car to the Royal Gunpowder Mills at Waltham Abbey for the 4th of July weekend, to take part in their festival of rocketry, which should be a real blast! There’ll be lots of enthusiastic model rocketeers and some very knowledgeable rocket pro’s in attendance, along with the firing of many rockets. There was some discussion about firing one of ours – but the lack of sufficient safety perimeter for such a large rocket knocked that idea on the head.

It should be a super and hugely entertaining event. If you’re in the region – why not pop along?

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01/06/09

06:44:42 am, by carolynne , 375 words, 36 views
Categories: Day to day

TOO HOT TO TANGO

Our on-track test didn’t go well.

We’ve been stopped by wind, rain and even snow before, but this time – it was just too hot!

It was 85degF under the tent. This meant we had to pump in nitrous against an 800psi nitrogen pressure. The poor old compressor really struggled to keep up with the demands of the nitrous pump. It took the best part of an hour to get only 8lbs in each accumulator.

We’d used space blankets to keep everything as cool as possible until the moment of fuelling but it didn’t really help. We had a start-time of between 1:00 and 2:00pm, which, from a temperature point of view, really couldn’t have been worse!

Every system was tested and cycled in the pits and it was all working. Just before we left for the start-line, Bev Battsford (Shakey’s pairing-lane Supremo, who'd very kindly volunteered to help us out on the day as a team member) warned us that it was over 100 deg.F, on the track, and at the end of the pairing lane. This was really too hot for the car. We’d come this far so we gave it a go.

When the word came over the radio to switch on the pilot nitrous – nothing happened. The ram and valve set-up that lets the starter nitrous in didn’t operate.

We got her back to the pits, let her sit in the shade, disconnected the pilot hoses from the rockets and tried the system. It worked. It looks like the heat had made it all go tight.

Very disappointing- again.

It was, after all, just a test of many new parts- all of which behaved themselves very well. A test we would have preferred to conduct in private.

On the bright side – the car was very gas-tight and everything held up well.

We’ll try again on a cooler day – with a more powerful ram on the pilot system.

I want to say a very big ‘thank you’ to the guys at Shakey, my wonderful team, and especially to Bev, who is recovering from orthopaedic surgery, but still helped immensely by bringing us safely to the start line, as she has done so many times before.

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23/05/09

06:24:42 am, by carolynne , 228 words, 56 views
Categories: Day to day

AND THE ROCKET IS FINE

A promised, here are the results of internal examination of the rocket:

We knocked the rocket apart yesterday. The fuel grain showed that the central cardboard tube was almost entirely consumed and the outer almost entirely intact. This is exactly the same result as previous examinations of fired rockets. The nozzle was also intact, with no sign of erosion on the hard edges. No evidence of any heat-effect or damage to any aluminium components.

A newly refurbished rocket has now gone back in the car, so there are four rockets, in the car, ready to go.

Over the next few days we are doing some work to improve the ballistic protection behind the cockpit and we're making and installing a better and stronger bash-plate underneath the pressure vessels and throttles.

We now must test this all at the track - we've made tentative arrangements with Shakey to do this on the 30th/31st May at the 'Yanks' Event. This has yet to be confirmed by the track officials.

We will not be out to demonstrate full terminal speed at this test. We just want to see a good, powerful run to 3/4 track and then assess the way she stops.

We'll keep you posted.

Team member, and Mac supremo, Will Campbell has now put together a 'facebook' page for Laffin-Gas, with reports, pictures and videos. See you on there!

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20/05/09

09:42:30 am, by carolynne , 905 words, 28 views
Categories: Day to day

Landmark Test Result

After six months of serious problem solving, engineering, safety testing and expenditure, today was the day to put it all on the line and conduct a live-fire test.

That’s a very nervous moment. It has taken several days to get the team all lined up, get all the necessary in place, and be ready to get it done. But more than all that there has been almost five years of hard effort spent on doing something which has never been done before with any degree of success or reliability. If this firing doesn’t go – the whole project is screwed.

We’d thoroughly discussed fueling protocol, both within the team and with our American mentor (who works on the Delta and Atlas Launchers), Dana Vandersaal (thanks Dana!).

We went for the slowest, most cumbersome (but definitely safest) method we could devise: Nitrogen first, to liquefaction pressure for the Nitrous Oxide, and then pump the NOS in to weight. This is the best way to avoid pressure shock.

I’ll post all the full technical data in a few days, but suffice to say the fuel load was light and the push-pressure quite low.

She burned like a good ‘un! We’ll probably have to choke her down!

It’s all been captured on video, and we’ll get them posted as soon as we can.

The car is definitely a go-er.

THE TECHNICAL STUFF:.

As usual, we want to share our acquired knowledge and data with all who may find it useful.

The last time we had the car at the track we failed to get full ignition on the start line. Trouble-shooting showed that al control systems were working as they should. The only difference between that set-up, and the one that had previously fired so well, was that we had sloped the nitrous vessels in the car, in an attempt to overcome the effects of forward (horizontal) G. It hadn’t worked.

After much calculation and experimentation we arrived at using pistons inside the vessels to maintain a complete physical separation between the gas and liquid. This prevents the lateral movement of the liquid N2O and prevents ‘blow-through' of Nitrogen (Which extinguishes the rockets).

In earlier blogs, you can read the saga of the development, manufacture and testing of these new ‘accumulator’ vessels.

In order to conduct a meaningful test it was essential to start with the exact set-up that had failed to perform last time out. The only difference had to be the addition of pistons. This meant that we had to fire a rocket in the car with all other possible variables constant, hence the firing of a single rocket, in the car down at the farm.

The Nitrogen side of the accumulator we were using was first charged to 650psi, which, at the ambient temperature on the day, would ensure that the Nitrous would stay liquid as it was introduced.

Each accumulator now has its own discrete pressure guage to allow us to monitor the increase in Nitrogen pressure as the N2O is pumped in.

We pumped in 8lbs of liquid N2O, looking for two seconds of ‘pilot’ ignition burn, and 3-4 seconds on main throttle. Nitrogen pressure had stabilized at 800psi, which is about 200psi lower than we normally use. After a little discussion it was decided to run at that pressure as we weren’t really concerned (in this test) with power output, rather actual full-throttle ignition.

When the car was chained down in position and all bodies (except mine, of course) were out of harms way, I performed a radio-instructed start sequence, exactly as we do it at the track.

The rocket fired beautifully. Just over two seconds on pilot and nearly five on mains. I closed the throttle with some N2O still in the system. This means that we are using the Ntrous much more effieciently than before. The team all thought that, despite the low state of tune, it was the most powerful in-car burn we had yet achieved. Sitting in the car while the burn was going on, I could have no opinion save the observation that the car had lurched forward with much more power than I was expecting from one rocket.

Reviewing both videos of the test, I now concur with the team. It appears that the piston have provided vastly more efficient delivery of N2O.

External inspection of the rocket showed that it had completely retained its structural integrity, it was only mildly warm to the touch, and it appears that the nozzle has settled into its taper by about 0.5mm. We will open the rocket up and give all the internals a thorough inspection. If there are any marked differences to previous firings, these will be passed on.

The rocket we used had been sitting around with an oil-soaked fuel grain for about six months. I wasn’t sure what effect this would have on performance. First appraisal says – no effect at all. This is a very useful result as it means we can stock-pile rockets ready for use rather than having to prepare them on the week of use.

This was truly the last hurdle. We are now confident that we can reproduce this firing at the track with all four rockets. Now I have to learn to stop the damnthing!!

Video of the test can be viewed on www.youtube.com/laffingastv

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02/05/09

08:12:22 am, by carolynne , 573 words, 34 views
Categories: Day to day

Friday May 1st:

Team Member Kim and I took four completed piston accumulators to Nottingham for pressure testing and certification at Jackson Keay Gas Cylinder Services. We weren’t wearing steel toe-caps so we weren’t allowed onto the shop floor to observe the testing up close. I stood at an office window overlooking the factory and watched as the bottles went on to the hydrostatic rig. It was a nervous half hour as I watched the bottles being filled with water and then hooked up to the compressor lines. We wanted them certified to 120bar, which is the standard for nitrous bottles and almost twice our maximum operating pressure. The big test gauge went up to 120 bar and stayed there. No leaks, no bangs, no breakages. The bottles were taken off the rig and stamped with the Jackson Keay cipher.

We’ve passed!

Jackson Keay are the foremost pressure vessel safety company in the UK, testing vessels for the likes of BOC and Air Products. You simply can’t have a more impeccable certificate than one from Jackson Keay. I’ve got to thank Fred Ayres, Neil and all the people at Jackson Keay for helping us out. For what has to be called a ‘nominal fee’, they have disturbed a busy production-line on three occasions to help us get through this vital process. They have been genuinely enthused about our little project and without them, well, we would have been well and truly stuck in the mire.

We got the accumulators home, popped them on the bench and shot the pistons up and down a few times with compressed air, just to make sure nothing had got jammed-up in the testing process. Now we’ve got to get them in the car, add all the plumbing and make sure there are no leaks.

We’ve added the over-pressure protection so kindly provided by FIKE but, even so, we’ve reviewed our fueling procedure to ensure that there is no risk of pressure-shocking the nitrous as it goes in. A light pre-charge with Nitrogen to provide damping is called for and that is what we’ll do.

The next step is to get the car down to the farm and fire one rocket in the car, to make sure everything works as predicted. We can’t see why it wouldn’t work, but hard experience has taught us to test everything. If that goes well, i.e. one rocket does a full burn, then it’s off to the track for a four-rocket burn in motion. We have that test penciled in for Shakespeare Raceway on the 16th-17th of May. I must emphasize that this run will be purely a test – not a performance. There is still much to learn about the actual power, getting the car stopped safely, and the amount of control the throttles give us.

After a hard off-season getting these accumulators built and tested, it’s back to the fun stuff of actually firing rockets!

A very big ‘THANK YOU’ must also go to Geoff Caswell of Caswell Engineering whose sponsorship and direct engineering assistance has been vital. The huge threads for the caps needed very precise cutting, which we simply couldn’t do on our old (and somewhat worn) lathe. Geoff came to the rescue by doing the thread cutting on one of his excellent CNC lathes and the result was a beautiful fit. Thanks Geoff!!

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IF AT FIRST…

The mark one accumulator has now been pressure tested. Oh dear! The welded flanges parted company from the vessel. Fortunately it was a hydrostatic test so there was no drama, just a sad exit of a flow of water. On examination, the actual weld material was fine but there was a crystalline substrate that had formed at the penetration boundary. It was, after all, an experiment, and now we know that the bottles don’t like even the best of welding.

David has been hard at work in a freezing workshop manufacturing Mark Two. This time we’ve gone for threaded construction as we know that the bottles hold a thread very well. A large cap made from high-grade billet aluminium is now screwed on to a fine thee-inch thread on the bottle. We now have to add the piston and the internal stops to prevent point-loading on the vessel and it’s back to the testers at Jackson Keay, who have been extremely helpful. David is very expert in the machine-shop and mechanical construction is an area of expertise – neither of us can make any claim to be experts at welding dissimilar metals!

The very cold weather has slowed us down a lot, so we’re behind schedule. Nothing new there then. We’ll be taking the new construction for testing in the next week or so and, if all goes well, David will press on with the other three accumulators.

We’ve had an interesting email from the NASA White Sands Testing Establishment, offering advice and consultation following on from the article we wrote about the explosion at Scaled Composites’ testing facility. It is very welcome and it does show that our efforts are being followed by some very serious people. Ever since that tragic accident in the Mojave Desert, we have had to back-track, consult, and re-design to ensure that our operations are as safe as possible. The addition of the accumulators is central to this.

Suppliers have come forward with specialist lubricants and explosion protection that have made it possible for us to move forward. Many others that we have contacted cannot get it together to make a promised phone call! In such hard times as these, it is a bit gob-smacking that the business-as-usual culture of lousy customer service still seems to be the norm in the U.K. We know that an order from us will not make or break any company, but the world is watching us now, and you’d think that, with the entire engineering sector under real pressure, there might be an effort to improve customer relations and to take advantage of any P.R. opportunities that might come up. The survivors of this recession will be the firms that make a real effort, and the ones where complacency reigns supreme can expect to end up on the scrap-heap.

We will be joining our American friends at Alconbury on March 5th to display the car and take part in their annual U.S.A.F. Motorcycle Safety Event. It’s good to see our American guests taking safety on our roads so seriously and we are delighted to assist in their efforts. As these folk can rightly claim to be the fastest bunch on the planet, we’re really looking forward to rubbing shoulders with some serious jet-jockeys.

The rest of our schedule for the coming season is still very sketchy as we don’t know exactly when we’ll be ready to have another go in public, but we are hopeful to be on track by late April or early May. We’ll keep you all posted.

Those of you who are reading this in our newsletter will be getting some photos of the new kit. Unfortunately the guys who did our website forgot to give us a facility to upload photos – and now they’re no longer in business. We’ll get the website sorted out soon (we hope!) but in the meantime, if you want pics, please sign up to our newsletter via the website.

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30/11/08

11:05:11 am, by carolynne , 844 words, 81 views
Categories: Day to day

Accumulating Knowledge

Well, we’ve messed around with the bladders and, several weeks ago, came to the conclusion that while the theory is fine, the practicalities aren’t. The material we can use just isn’t up to the job.

So the problem of a physical barrier between the Nitrogen and the liquid nitrous was still with us.

A few months ago, we started looking into high-pressure accumulators and spoke with the people at Hydac, and one of their dealers about their excellent diaphragm accumulators. They are definitely up to the job. Unfortunately the standard ones are made from steel, which Nitrous will corrode, and which are far too heavy for our application. The purchase of lightweight aluminium versions was way beyond our finances.

The only alternative was to build accumulators ourselves. We decided that free-floating pistons were an arrangement that we could manufacture in our own machine-shop. Diaphragm construction was out of the question for us. This is a big step, and safety of operation must always be to the fore in our design and operation. Whatever we build has to be tested at pressures well above those that would actually be used in service.

The first accumulator is now well on its way. We’ve had John Shakeshaft weld a very sturdy flange around the outside of one of our 220bar vessels and cut the vessel across the centre of the flange. David is now working on the ally piston we’re going to use to free-float between the gas and liquid. We’re using 3,000psi hydraulic seals in the system. As we operate at around 1,000psi (75bar) there’s a good margin for safety and reliability. Before any high-pressure gas goes anywhere near it, the accumulator will be subjected to an independent hydrostatic test to ensure its integrity at well above our service pressure.

With a solid barrier, such as a piston, in the system, our over-pressure protection has had to be reviewed, as we need protection on both sides of the piston. Fortunately the people at Fike, (an international engineering and manufacturing firm specialising in explosion protection) have come though for us and are providing (at their cost!!) the finest burst discs and holders. There will be one on the output end of each of our pressure vessels and one disc will be sacrificed as part of the hydrostatic testing. To the folks at Fike, we must say a very big THANK YOU!! Especially to one very bright lady engineer (we like lady engineers!) - Yvonne and to Keith, the manager with some real marketing vision. We do hope that we can continue this collaboration. Needless to say, there’ be a FIKE logo on the car and we’ll be there to asssit in their PR and promotional efforts. For anyone interested in what they do and what they can supply, please take a look at: www.fike.co.uk/contactus.htm .

If all goes well, and we’re happy that the construction is more than adequate, we’ll be doing a single-rocket test in the car to ensure that all works as it should in relation to the rest of the systems in the car. There’s no doubt that the piston will do the job of partitioning the gas from the liquid in theory, but there is no substitute for practical experimentation.

While we're thanking people: A big 'thank you' to Geoff and Sue Caswell of Rushden engineering company; G. Caswell Engineering, who've come on board as a Development Partner and started by donating a beautiful TOS milling machine that has already made our lives so much easier. The Caswells make super high-quality stainless-steel fittings for process industries and for medical applications. So we now have a source for those bits of 316 stainless that we keep seeming to need! It's great to have support from people who are committed members of our local community.

The body of knowledge we have employed has been the result of very expensive and time-consuming development by lots of folk. We have always acknowledged Charles Berg’s efforts – it was because of Charles’ openness and willingness to share what he knew, that we even got started on our car. Charles has continued to give input as time has gone on, as have others all over the planet. For our part, we too have discovered and developed lots of useful stuff which we have been happy to share with anyone with an interest in hybrid rocketry. The accumulation of this knowledge is a community affair, and long may it continue.

This sharing would be stifled if any of us in this community fail to acknowledge the input, work and expense of others. We are happy to share – but get a little miffed when someone comes to our house, gets the low-down on all that we’ve learned and then claims he figured it all out for himself. Use the knowledge by all means - we all stand on the shoulders of others. To acknowledge that is model behaviour, to claim it for your own is plagiarism.

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05/11/08

04:11:47 pm, by carolynne , 363 words, 104 views
Categories: Day to day

You just never know

A couple of weeks ago the media were full of the new Richard Noble project: "Bloodhound". 1,000mph in a land vehicle would be no mean feat. I was interested to see the government backing citing 'getting youngsters enthused about science and engineering'. I'm all for that.

We've just learned the hard way that an economy cannot live long on a diet of consumer credit and shopping. At some point, someone has to create the real wealth that pays the shopping bill. For the UK, this means high value-added engineering and science. We can't compete with the low labour costs of the Far East in mass-manufacture so we must concentrate on the high-end products and science. Yet we know that science has become the poor relation in the school curriculum, very often being taught by teachers who have little or no science or engineering backgound, who have been press-ganged into teaching the subject.

When we are at the track with the car, we're always surrounded by youngsters asking great questions and getting utterly enthusiastic. So we contacted local schools and people involved in education, offering to take the car to their school and let the children enjoy a science lesson based around the car. To our dismay, not one school ever got back to us.

So, when the 'Bloodhound' project hit the news, I contacted the local BEEB to vent our frustration. They did a story for the regional programme, that barely touched on the educational issue but it was a fairly well done little piece.

Then a couple of press agencies got in touch - then an article went out in The Mail Online, and Metro. They didn't quite get the facts right - the media never do. So we never claimed to have 8,000lbs of thrust -HONEST!!

Now the whole world wants to know about laffin-gas and that's great for us. But it's not what we were really after. We want to connect with the youngsters and let them see what fun and adventure can come from science and engineering. The youngsters, we are sure, will do the rest. So, schools, teachers, technical colleges - get in touch and we'll be there!

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21/08/08

07:35:34 pm, by carolynne , 1800 words, 322 views
Categories: Day to day

THE BIG BOYS SCREW UP

About three years ago a bloke blew up a rocket car at Santa Pod. It wasn't our car. We had nothing to do with it. Since then we haven't been able to run there. We are based three miles from Santa Pod and we have to drive to another track, Shakespeare (which is a great place), in order to be able to carry on our project. I only mention this because it's an example of how someone else, that you have absolutely nothing to do with, can screw up, and thereby mess with your life (a bit like a drunk driver!).

That's all pretty minor stuff really. What 'Scaled Composites' and 'Virgin Galactic' have been up to is truly jaw-dropping. They killed three people, seriosuly injured three more, and then refused to tell anyone exactly what had actually happened. The offical California 'Health and Safety Report' has never been published, even though 'Scaled' were fined $28,000 for violations. Of course, when you realise that 'Scaled Composites' is controlled by Northrop Grumman (a true Aerospace/defence giant) all becomes clear. God, I wish we had that kind of pull.

By refusing to publish the relevent data, 'Scaled' have put everyone involved in Hybrid Rockets in a jam. Did something happen that we haven't designed for? Should we stop until we get the facts? What if someone gets hurt? Their screw-up, our problem!

The following two items are the recent Press-Release from 'Scaled' and a letter sent, by myself, to a couple of leading journals. (What's the betting they'll ignore it?)

SCALED COMPOSITES, LLC

August 1, 2008

The rocket oxidizer cold-flow test accident of 26 July 2007 at Scaled Composites was a devastating event. It caused the death of three co-workers and serious injuries to three more. It produced untold grief and turmoil for immediate families and friends of those killed and injured, as well as to the Scaled family. All of our lives were changed that day.

It should go without saying that we were completely surprised by this accident, as we had conducted numerous tests, without incident, on similar systems including the SpaceShipOne rocket motor. The body of knowledge about nitrous oxide (N2O) used as a rocket motor oxidizer did not indicate to us even the possibility of such an event. However, because this serious and unanticipated accident had occurred, we had to look back at what had happened and where we go
from there.

After doing our best to take care of the families and each other, the first order of business was to work with Cal OSHA in its investigation of the accident. Cal OSHA took through the end of January this year to complete its investigation. The agency did not determine a cause for the accident. We are continuing to work with Cal OSHA. In doing so, we hope to support Scaled’s needs as well as the ongoing efforts of others in this developing industry.

In addition to the OSHA investigation, we put in place our own Accident Investigation team, composed of 11 members from the industry and from Scaled, with a collective rocket development and testing experience of over 200 years. Scaled also worked with NASA to
conduct basic materials incompatibility testing. Based on the findings of this Accident Investigation team, Scaled has implemented a variety of improvements to enhance the safety of the N2O hybrid rocket motor.

The improvements and plans include:

Conducting increased compatibility testing between N2O and any materials that contact it in the tank and eliminate incompatible materials in the flow path;

Revising cleaning procedures to further minimize the risk of contaminants in the system;

Replacing the composite liner in the N2O tank with a metal tank liner;
Diluting N2O vapor in the tank with Nitrogen or another inert gas to decrease its volatility and/or act as a pressurant;

Designing additional safety systems for the N2O tank to minimize the danger due to tank overpressure; for example, a burst disk feature; and Increasing the amount of testing during the development program to demonstrate that these design changes, and any improvements to system components, prevent the sequence of events that led to the accident.

Finally, we have formed an Advisory Board comprised of rocket industry experts to oversee theimplementation of our improved designs and procedures going forward. These procedures, aswell as the improved test site safety procedures that we hope to develop with Cal OSHA, will greatly enhance program safety for the future.

The industry will be provided with any pertinent materials compatibility data and/or testing protocols we develop as we move forward.

RISKY BUSINESS

Space Ship One – the Virgin Galactic Challenger is an amazing project.

A small rocket powered ship is taken to altitude by one of Bert Rutan’s innovative aircraft, built specicaly for the job, and then the rocket-ship powers off into sub-orbital space. It is designed to offer the experience of space-flight to the general public, and is being promoted by that Paragon of all Promoters; Richard Branson and his ‘Virgin’ brand.

'Scaled Composites' is the company, founded by Bert Rutan, that is doing this great project. These were the guys who built the aircraft which circum-navigated the globe, and many other fabulous pioneering aircraft. There is no way such a small operation could fund a space-flight project, so Bert sold a controlling interest to Northrop Grumman, one of the aerospace giants. There’s always a down-side to such a move, as big corporations do not operate by the same rules as the little guys.

A little over a year ago, there was an explosion at the Mojave Desert centre, in California, where the work is taking place. Three people were killed and several more injured. This happened during a ‘routine’ fueling test, where the oxidizer for the rocket (in this case Nitrous Oxide) was being transferred, from a storage tank, into the pressure vessel for the rocket. Subsequently 'Scaled Composites' were fined $28,000 for violations of health and safety rules. (which would seem to many a paltry amount for three dead and three badly hurt). The California OSHA (the local health and safety authority) report was never published. On the first of July this year, 'Scaled Composites' issued a press-release concerning this incident. The last line of the release states:
“The industry will be provided with any pertinent materials compatibility data and/or testing protocols we develop as we move forward.”

Scaled Composites are not the only people working in the field of high-powered Hybrid Rockets (the type of rocket being used), so sharing of information is the responsible and ethical thing to do. Well done Scaled Composites! Well - not quite!

The press release contains no useful information as to exactly what occurred, what materials, methods and protocols were being followed nor the source of ignition. No engineering or scientific data has been released. The Health and Safety report has been withheld. Three people were killed. That experience should, at the very least, translate into a sharing of knowledge that would enhance the safety of others working in the field.

I must disclose a personal interest at this point. I am also involved in the development and application of powerful Hybrid Rockets. In their report, 'Scaled' identify certain ‘new’ safety procedures, including the use of inert gas and over-pressure protection. We’re a very small operation, yet we worked out that these steps we’re needed three years ago, before we took the step of firing any rockets. So, as big as their operation is, mistakes have been made, and now commercial secrecy prevails (as per usual), at a big Aerospace Corporation. I have the greatest of respect for Bert Rutan. He is probably the finest aerodynamicist working today, and I’m sure this secrecy is not down to him.

It is the normal practice, in scientific circles, to share data. Especially when that data is pertinent to the safety of other scientists. In fact, it is considered to be basic ethics. Northrop Grumman have decided not to do this. They seem prepared to allow others to take risks that could well be avoided, by witholding the one good thing that may have come out of the tragic loss of three lives; information.

In the press release they also state:
“It should go without saying that we were completely surprised by this accident, as we had conducted numerous tests, without incident, on similar systems including the SpaceShipOne rocket motor. The body of knowledge about nitrous oxide (N2O) used as a rocket motor oxidizer did not indicate to us even the possibility of such an event.”

Whoa there! The 'body of knowledge' certainly predicted the possibility of such an event. Many other engineers working with Hybrids will confirm. What they should have said was “We didn’t know”. One wonders what else 'they didn’t know' and what else they still don’t know. This matters because they haven’t figured out the root cause of the event. The impression left is that they truly haven't a clue. If all the data relating to the incident were to be shared, perhaps there are others who can figure out exactly what happened. Unfortunately that possibility is not to be allowed.

The accident demonstrates that, like the rest of us, 'Scaled Composites' is fallible and not in the least omniscient. We are now to trust that, as they continue to operate in their own splendid isolation, they will not get it wrong again. One is reminded of how Morton Thiokol made a commercial decision that cost the lives of a Space-Shuttle crew. (I should explain that Morton Thiokol built the solid-fuel rocket boosters that leaked and blew up the 'Challenger' as she launched. Engineers warned that the weather was too cold for the seals and that a catastrophe would follow. Senior mangement made the 'business' decision to let the launch go ahead. The rest is history.)

We have tried to contact Scaled Composites on several occasions in an effort to share data in the spirit of scientific co-operation. They have never replied. Not even with a ‘No thank you’. They are obviously too big and too clever to talk to the likes of us. Oh, up to this date, despite fueling and firing dozens of rockets, we haven’t blown anything up. (YET!)

This commercial secrecy is unforgivable and unethical. It is also criminally dangerous.

I, for one, would be just a tad nervous were I to be on board when that rocket fires up. Knowing what you now know, would you pay a couple of hundred thousand quid for a ticket to ride?

Big organizations such a NASA have demonstrated, on more than one occasion, that commercial consideration comes before life and limb. Here we go again.

Carolynne Campbell
Chief Designer
Laffin-gas Xperimental Hybrid Rocket Car Project

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04/08/08

08:30:24 am, by carolynne , 1150 words, 112 views
Categories: Day to day

Rocket Royalty on a Flying Visit

Sometimes getting things wrong can give wonderful results. When I first put the laffin-gas.com website together, I included a short ‘potted’ history of rocket cars. I wanted to give proper credit to those who had come before. It was full of inaccurate information, as the sources I had used were also full of inaccurate information. The result was lots of emails –some from true anoraks, some from nutters threatening retribution and some (very few), from people who actually knew what they were talking about. A few weeks ago one such message popped up: “Gary Gabelich didn’t own or build Blue Flame, he was a hired driver,” from Dick Keller.

Even I knew who Dick Keller was – he’s the man who built just about all of the big peroxide rockets and many of the cars they went in: X1, Pollution Packer, Blue Flame, Vanishing Point and many more! I replied, thanking him for getting in touch and putting us right. A correspondence followed on from that, with Dick giving little hints and tips and encouraging comments. Then Dick tells me that he’s coming to Manchester in late July, and perhaps we could meet up. I jumped at the chance. This man knows more about rockets and cars and aerodynamics and fluid dynamics and…. This was an opportunity I could not miss.

It turned out that Mr. Richard A. Keller III (RAK III !!) was competing in the European Masters track cycling championships at the Manchester Velodrome, representing Ireland, and he had a day off between races, and that he would like to come and see the car!

If Dick Keller was taking the time out to see our project, it was only good manners that I should take the time to see what he was up to on the cycling track. So, last Tuesday, I set off from Northants to go to the Manchester Velodrome and watch the man race. I arrived in time to see three very fit men on bicycles thrashing round the track, elbows and shoulders flying, in a knock-out to get to the semi-finals of the 70+ sprint race. The winner? Richard Keller of Ireland. I spent the afternoon watching great names of cycling giving it maximum welly around the track and very entertaining it was. I even got video of one of Dick’s races. Dick took time out for a quick lunch and we chatted about cycling as we munched on disgustingly healthy stuff, and made arrangements for the following day’s trip to see the car.

I met Dick for breakfast at his hotel and we set off for Northants. The drive down was amazing with Dick telling about Blue Flame, his other cars and all the various colourful, sometimes dodgy, characters from the early days of drag racing and the heyday of thrust cars. Sprinkled throughout the conversation was a litany of personal friends of Dick’s that was a Who’s-Who of the time: Chuck Suba, Art Arfons, Walt Arfons, Don Garlits, Craig Breedlove, Sammy Miller, Andy Green, Bert Ruttan… and through it all a self-effacing matter-of-fact demeanour – just a mad cyclist telling the tales of his adventures without ‘bigging anything up’. This guy had been right in the middle of all those amazing things we’ve only read about.

Hubby David introduced himself as we got through the door, on went the kettle as Dick looked out through the patio doors at the waiting beast. He was out the door before I could pour his cup of tea. It was a bit like waiting outside the Headmaster’s study as he inspected the car from one end to the other, muttering to himself as he went. I gave him a couple of minutes and we followed him out.

He took us through the car from front to back – and his entire initial interest was its safety features – no discussion of rocketry – just safety. This wasn’t entirely surprising as Dick has seen a few people die in rocket cars – all of them good friends of his.

First the steering column – was it designed to collapse? What kept it from spearing the driver? (Referred to as ‘Precious Cargo’). After a little further inspection and discussion the steering was given the ok. It went on - every detail that affected safety. In the end the headmaster’s instructions were to put in a much stronger blast shield, sort out a better inclinometer, modify the parachute mountings and put shrouds around the nozzle area. His reasoning in all cases couldn’t be faulted and it came from direct, sometimes fatal, experience. Keller’s will be Done!!

Only then did discussion turn to rocketry and fluid dynamics. Now we were going to get a critique from a guy who’d worked on Saturn and designed and built all the early H2O2 rocket motors for cars. We went through everything, nozzle sizing and design, volume to surface-area ratios, fuel delivery and shut-off capability, the bio-fuel concept and why four rockets instead of one big one. Having looked at the hardware, Dick took a look at testing videos. The verdict? She’ll do the 300mph once we’ve got the gas separation sorted! In the opinion of the man whose opinion really matters, we were not barking up the wrong tree and our development was close to fruition. What a relief. If Dick Keller had thought we were not going to make it, he would have said so, in the nicest possible way, of course, but there’s no bullshit to be had from him.

Then Dave Coleman of Quarter Mile High showed up with his cameras and we were able to record a discussion/interview. Can’t wait to see the result! Hopefully QMH will make an edited version available to the public as it will be quite an historic documentation of the views and experience of the most famous rocketeer of them all.

During the filming, David Rose and Fred Thomas also appeared and we were all able to chat and ask questions for another hour before it was time to get Dick back to Manchester and to his first love – thrashing bicycles to death!

We learned so much in such a short space of time and, I hope, found a new friend and collaborator. It’s not often you get to know someone who is head and shoulders above the rest in his field. It’s taken several days for it all to sink in and now we’ve got a load of work to do to comply with the Headmaster’s safety instructions. If you don’t listen to one who really knows, then you are truly an idiot.

Oh! The cycling! Richard Keller of Ireland’s final medal tally in the European Masters:
3 Silver and 1 Bronze medals out of four events participated in. Not bad for a seventy-year-old bloke!!

NOSTALGIA, CONUNDRUMS AND A GREAT WEEKEND

It’s been the normal practice to post a report in the week after a trip to the track. It’s taken longer this time because we were doing our best to solve a mystery. Every time we diagnose things at the track, we get home, look at the evidence and come to a different conclusion. We were all convinced we had developed an electrical gremlin and spent hours at the track trying to track it down. Glenn Stockton and I went over all the systems, testing everything early on Sunday morning and we did find a dodgy switch. Thinking that we had found the Gremlin, we got the car ready, took her to the start line and fire her up. Just like the two tests the day before, she blew out just as I opened the main throttles.

Back at the pit, three of us said ‘the only thing we’ve changed is the angle off the bottles’.
None of us really thought that it was the problem but Glenn suggested looking into putting bladders in. It turns out that the bottle angle was the problem – no gremlin!!

So it’s a problem: Put the bottles back upright and she’ll launch fine but there’ll be a problem with nitrogen blowing through as she starts to pull G. Leave them angled and she’ll blow out on the line. It’s got to be bladders. We’ve contacted a couple of firms who deal in this stuff and custom made bladders are on the way. Bladders enable us to completely separate the N2 from the liquid N20, allowing the clean delivery of Nitrous at any bottle angle at under any Range of G force. The question is – can we make them hold up at the operating pressures we have to use? We think we can – only testing will show for sure.

We’ve got to get them installed and do some testing before going back to the track for a full on-track test.

Was the weekend a bad one? No. The whole team was very encouraged by the exercise. We’d been able to be part of the NSRA’s super event, with a very knowledgeable and supportive crowd. We’d got three tests in, in one weekend, which was a first and very, very productive in terms of learning things quickly. The team had turned the car around and got her ready each time with no sweat and proved that we could make start times over a weekend. Yes we burned a lot of nitrous and a lot of money, but it was probably the best outing yet.

When she’s ready, we’ll be back!!

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20/06/08

08:30:06 am, by carolynne , 285 words, 86 views
Categories: Day to day

150 LBS OF NITROUS SHOULD DO THE TRICK!

With 150lbs of Nitrous, eight rockets, spare pyros and a full crew, laffin-gas is going for it at the NSRA Nostalgia Nationals at Shakespeare County Raceway on the weekend of 28th/29th June.

The season, so far, has been plagued by rain, snow, wind and events beyond the team’s control that have, so far, stymied our attempts to get in a full-pass on full power. We are now making sacrifices to the Weather Fairies (they’re real, you know) in hopes of clear weather and a fair chance at getting her down the track.

The people at the NSRA (National Street Rod Association) have kindly invited us to their rather special event and have even allowed and exception to their ‘No Rear-Engined Cars’ rule, (our rockets are in the back of the car!!).

About twenty five years ago, David was working in a foundry and he made some castings of on old NSRA plaque. We found three of them during a clear-out of David’s workshop and two have been donated to the NSRA. We expect one may appear as the centerpiece of a special Twentieth Anniversary Trophy to be presented at the event. Amazing how these things happen, isn’t it?

We’ve made a few modifications to the car, to make the controls a little more forgiving and to ensure a reliable supply of gas to the air-ram that gets the burn going. Now it’s really got to be show-time!

How fast will she go? We really don’t know. But, if the way she went off the line at the first meeting of the year is anything to go by, a full pass at full power should be pretty quick!

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06/05/08

07:41:43 am, by carolynne , 432 words, 87 views
Categories: Day to day

NO GO ON THE BANK HOLIDAY

I must be a prophet! In my last press release I ended with a cautionary note:

“This is drag racing and even the best cars don’t go every time and the weather can always interfere.”

What a spot-on forecast.

We arrived on Friday for Set-up to be ready for a run on Saturday. We were scheduled to run at the end of the day’s qualifying sessions. All the crew were there and we were ready to go. Just as we were about to put the gasses into the car, a racer put his car through the starting lights and went into the barrier. That closed the track for the rest of the day. The Saturday run was off!

Sunday – it rained. They dried the track – then it rained. And so-on and so-on. Later in the day the truck carrying the track drier did a graceful pirouette and crashed into the guard-rail wrecking the track drier. Sundays run was off!

David and I returned home for a decent night’s sleep in our own bed, and headed back to the Raceway early on Monday morning. The weather was fine leaving home, but as we neared Shakespeare, the heavens opened.

We sat around all morning. The track wasn’t dry and ready until 2:00pm. Ahead of us were a couple of hundred racers, all as desperate as us to get a run in. The organisers were franticly attempting to fit a full day’s racing into the next four hours and, frankly, it all got a bit shambolic. We need an hour’s notice to gas-up and ready the car. The notice didn’t come. When we finally got a go-ahead, we gassed up and ended up waiting for an hour in the pairing lane. The car is not designed to sit and wait once it is fueled.

We went to the line, fired the pyros, and the pilots did not come on. We’d lost pressure in the air system that operates the pilot valves. No run! And no time to return to the pit, replace the pyros (which we can do in about 40mins) and try again. Racing was over.

We were gutted, but then so were a couple of hundred other racers, including guys who’d come all the way from Sweden and accomplished nothing. There were many grim faces in the pits.

Ah well! That’s Drag Racing!!

We’ll be back out in a couple weeks at a less frenetic event, hopefully with the weather Gods smiling upon us, and we’ll get her down the track.

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29/04/08

07:16:22 am, by carolynne , 372 words, 72 views
Categories: Day to day

READY FOR BLAST-OFF AT SPRINGSPEED

We’re off to Shakespeare County Raceway this coming weekend for a full-fuel burn down the track.

The first track test of the year was inhibited by lousy weather, (sleety with a strong cross-wind) so we only attempted a short burn. The car went off very strongly, but blew though the Nitrous sooner than we had anticipated for the amount of fuel we’d put in the car.

The last two weeks have been very, very busy while we tore the fuel system apart, re-mounted all the gas cylinders at an angle of 40deg and re-jigged all the high-pressure hoses to fit the new configuration. The result is now pressure-tested and working fine and the car looks much better with a lower and neater profile behind the cockpit. More importantly the set-up now allows for forward ‘G’ much better and will make much better use of the Nitrous.

Rockets are now sitting in the oiling rig, soaking up a few litres of bio-fuel and there are loads of last-minute jobs still to do.

‘Springspeed’ is the first major event of the year at Shakespeare with hundreds of racers competing in everything from frightening ‘Fuel Altereds’ and heavy American V8 monsters to Lightening fast drag-bikes. So for us, there is real pressure to perform and perform well.

After successful winter testing, and a very positive first outing, our confidence is fairly high, but this is drag-racing and it’s a very unpredictable sport. Even the best cars don’t go every time and the weather can always interfere, so we will need a bit of luck for everything to go well.

Knut Soderquist (One of the most successful Top-Fuel owners, who helped Carolynne in the early days building the chassis) paid us a visit last week. He is very excited about the car. “One good run is all you need now” he told us, “There are people from Lithuania to Thailand who want to book you car.” If anyone in drag-racing can deliver international bookings, it’s Knut. So no pressure there, then!

We hope to see all our supporters at the track – not just to see us, but to expose them to a fantastic weekend of top quality non-stop action at Shakespeare.

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15/04/08

05:15:19 pm, by carolynne , 274 words, 69 views
Categories: Day to day

AND NOW FOR THE TECHIE BIT!

We were surprised by how quickly the Nitrogen blew through the N2O on the last run.
David Rose pointed out the effect of the forward ‘G’ on the level of the liquid surface in the bottles. Doh!!

Back home and digging out the ‘O’ level physics, I drew a few force diagrams. At 1G the surface slopes to 45deg, at 2G it slopes to 72.5 deg.

No wonder the Nitrogen pushed past so quickly! Now we’re modifying the car and angling the bottles in the chassis. The ideal angle would be 27.5deg from horizontal. In order to accomplish that, we would have to lengthen that area of the chassis. Not too big a job on its own, but when we consider the wiring, controls, parachute cables and all the other stuff involved, we’ve decided to compromise.

The bottles are being mounted at 40deg. from the horizontal. This means that, at 2G, the surface of the liquid will slope across the bottle at 32.5deg. This we can live with by compensating with an over-fill of the N2O.

The result should give us a much longer full-power burn, using an acceptable quantity of Nitrous. We aren’t happy with the idea of leaving several pounds of nitrous behind and then having to vent it to atmosphere. N2O is a nasty greenhouse gas and venting several pounds after every run is not really acceptable. So we’re devising a recovery system to return unused nitrous to storage and minimize the need to vent.

Right now, the car is in pieces while we work on the modifications. Ah the joys of asn experimental car!

A SNOW DODGING START

Saturday April 5th 2008, Shakespeare County Raceway.

It was sleeting as we arrived in the transporter and blowing a strong and very cold north wind. The rest of the team was already there and we got the car out, covered her up, climbed back into the bus, closed all the doors and put the heater on.

It was already obvious that there would be no fast run today. There’s a break in the weather, so Rachel and Will took off the top panels and hub-caps ready for Glenn Stockton to give her his usual thorough scrutineering job. There were a few new bits and modifications done over the off-season and I went over everything with Glenn. As usual, he picked up a couple of small items that needed rectification. You don’t get anything dodgy past HIM!

Then the rain/sleet returned. Conversation is the transporter turned to “Do we run, don’t we run.” The unanimous decision was, “we’ve come this far, let’s at least get her on the track, if we can, and do a launch to prove the ignition in track conditions.”

Another break in the weather, the sun appears and we can see the track crew working their socks off trying to get the track ready. Susie and David Rose put a small (for us) dose of nitrous in the car, while Rachel, Susie and Will went through the safety check-list.

Once the gas is in the car, we only have a couple of hours before the pressures start to drop, so now we really need the weather to hold up. Here comes the rain… a heavy shower sends us back into the old race-bus.

It takes an hour before the track re-opens and we decide to go for it right away. As we push the car into the fire-up lane, the P.A. announces “Treaded tyres only on the track”. That tells us that the track conditions are not suitable for a high speed run. A launch would be safe enough, though.

The crew pushes me to the line, final radio check, and Dave Rose gives me the thumbs-up.

Fred comes on the radio, car switched on and, on Fred’s commands, I initiate the ignition sequence. “Pilots, Pilots, Pilots” comes over the radio. I turn the switch and feel her light up well. “Go,Go,Go,” Throttle full forward and she leaves strongly, by sixty feet I can feel the power dropping as the Nitrogen starts to push through the small amount of Nitrous in the bottles, I let her run to half track, and shut her down, coasting through to the end.

She’d done exactly we expected. There was no damage to any of the rockets or structures in the car and absolutely no mess on the track. I was a bit crestfallen that I hadn’t been able to give her a full blast, but everyone else was very happy. We’d got a good launch, proved the car in race conditions and we hadn’t blotted our copybook.

As we got back to the pits, down came the weather again. It turns out that we’d taken our only opportunity of the weekend as Santa Pod-like snow descended on Sunday. That was lucky!

We’re talking with Jerry Cookson at Shakespeare about the date of the next run, when, weather permitting, we’ll fill her up to the brim and really have a go.

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27/02/08

11:30:50 am, by carolynne , 278 words, 83 views
Categories: Day to day

Southern Manufacturing and FIRST RUN OF THE YEAR

Firstly, many, many thanks to Phil Valentine, Adrian Jones and all the folks at Southern Manufacturing Show for making us so welcome and being so helpful. They even removed a wall so we could get the car into the hall! We had a fantastic space, which became the 'village green' for the show.

Reaction to the car and to our technology was superb. Being amongst so much superior British engineering with our home-grown project, and to be taken so seriously was a real compliment.

Was it worth it? Absolutely! I would recommend this kind of show to other racers. Being the only car really helped us to stand out and get our message across. Sometimes we racers get too caught up in our own little world and don't expand our horizons. The Autosport show is fine - but one gets lost amongst all the other racers and cars.

You also get exposed to a base of potential sponsors that otherwise you would never meet. Lots of firms have offered parts and services to help the project and with the build of the new car.

FIRST RUN!!

Our first chance to test the new pilot ingnition set-up, that performed so well in tethered testing, will be on 5th and 6th April at good old Shakespeare Raceway.

We're not sure yet if the run will be on Saturday or Sunday. It depends on both the weather and the team's other commitments.

We'll be going for a full burn of all four bio-fuel rockets and a good parachute test.

The car is ready to show some real performance this year and all the action will be at Shakespeare so don't miss it!

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18/12/07

03:33:53 pm, by carolynne , 118 words, 107 views
Categories: Day to day

Southern Manufacturing Exhibition 6/7 FEB 2008

The car and the team are going to be on show at this expo at Farnborough in February. It's mid-week show, so we're giving plenty of advanced warning!! you can find all you need to know at www.industry.co.uk .

We're bringing on board some new Development Partners (to be announced as soon as deals are done and dusted.

The guts of the NEW CAR - laffin-gas2 will also be on show. The next generation car will be a big leap forward from the present machine and will be built in the next few months, hopefully almost entirely out of composite materials!!

Weather, and Authorities, permitting; well be doing a run on the fantastic Farnborough runway!!

Stay posted.

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05/11/07

01:44:47 pm, by carolynne , 741 words, 314 views
Categories: Day to day

Tethered Test 03-1107

Having experienced ‘blow-out’ of rockets in the car when opening the main throttles, we examined the differences between the in-car systems and the systems we use in static-rig testing of single rockets.

The car contains safety systems to ensure responsible operation on the track, which are unnecessary in static testing, so these were examined in detail. The solenoid valves for instant shutdown had been used in the test-rig, although not every time, and from going over our records, we found that the test rig performed reliably with or without the solenoid valve. Other safety systems did not directly impact on the actual rocket systems in the car, but gave the driver and crew finer control of events. This meant that we could discount the safety systems as a cause of the blow-outs.

Further examination of the differences between what we were doing in rig-testing and in the car, showed a major difference in the pilot ignition system. In the rig, we use a small ball-valve drawing from the main nitrous supply, just prior to the main throttle. In the car we have been using a supply from a single bottle and distributing the N2O to the four rockets by means of a manifold. We had previously observed that, though the manifold is designed for equal distribution, it was not feeding pilot N2O equally to all four rockets. On one run, earlier in the year, the car had gone on two full burning rockets and main ignition was not achieved on all four. The normal solution for this, in hydraulic systems is to use flow-controllers to balance the system. We had put flow controllers on all four outputs from the manifold and achieved an even distribution. It was only since we had installed these flow-controllers that the blow-outs appeared.

The manifold and flow-controllers were identified as the only critical difference between the test-rig and the in-car systems. We decided to reproduce the test-rig in the car, meaning, four discrete N2O systems, each with one pilot valve and one main throttle valve feeding from one bottle to one rocket.

We had arranged to perform a static tethered test of the new systems in the car, in a reproduction of start-line conditions on the previous Wednesday. Unfortunately, despite having ordered the N2O well ahead of time, our supplier informed us on the day of the test, that he could not supply the gas. We were unable to perform the test that week. Steve, at Motorshack, came to the rescue by supplying the gas at short notice, but the static test was not going to get done that week.

We decided to take the car to Shakespeare Raceway that weekend and test the new systems at the track. Unfortunately bad weather stopped us for the very first time.

Today we performed the tethered test down at the farm in Grendon. Carolynne suited up and got into the car which was restrained by heavy chains to the rear and a balancing tether to the front. We simulated the actual start-line procedures using radio commands and all the usual set-up and fuelling methods. The only difference between an actual run and this test was the tethering of the car.

All four rockets ignited strongly on the pilot gas and Carolynne was instructed to throttle up. All four rockets switched over to main throttles and burned at full power for a little over six seconds.

After the firing, the car was examined for any structural effect. All four rockets were intact with no sign of leakage and all four graphite nozzles were also intact. The structure holding the rockets in the car was also entirely intact, with no measurable distortion to end-plates, cross-braces or chassis mounting points, thus demonstrating that the structure of the car is well capable of handling the effects of four rockets running strongly.

As has been demonstrated by other designers, it is not difficult to get rockets to fire in a car, but doing it with adequate safety systems and with the engineering standards required to maintain structural integrity requires quite advanced and careful engineering design and execution. We are happy that we have now demonstrated that this car is both safe for track operation, and capable of reliable high-speed performance.

We now have a working and reliable four-rocket hybrid rocket car.

Fuel used:
8lbs N2O per rocket.
800psi N2 in the push system.
Cardboard liners soaked 75% with Bio-fuel.

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04/09/07

07:11:57 am, by carolynne , 428 words, 117 views
Categories: Day to day

Development and testing

After every track test, the whole team stops off at the pub just up the road from Shakey and we go over what happened. After the last test (where we lit four rockets but they burned with very low energy), we all decided to park the car until the fuel problems were solved.

I'd discussed the problem of the sheer unpredictability of the cardboard fuel grain with Glenn (safety supremo at Shakey). I'd suggested going back to plastic liners. Glenn was against the idea and he had a good point. The plastic goes well but it's dirty, smokey and leaves little strings of plastic all over the track. So the next idea was to try soaking the cardboard in cooking oil. (Bio-Fuel!)

We knew that this would be powerful, but it was an unknown quantity. It meant a whole series of single-rocket static tests (expensive!!) to get on top of the new fuel combination. The last report tells of our first test. If we'd used that set-up, we would probably have blown the back off the car!!. So we've done a series of tests varying the nitrous flow and the amount of bio-fuel we put in. Now we've got manageable rockets that will be safe in the car and they're very tuneable, with a thrust range of between 1,000lbs and 2,000lbs per tube.

We can now go as fast (or as slow) as we wish.

Glenn had also expressed concers about the very narrow rear track. If we had a blow-out, or, for any other reason, the car got seriously sideways it would probably roll over. He was right and we agreed with him. So while we've been developing the new rocket, we've widened the rear track by over a foot and added super hard shock absorbers. This means the car is much more stable laterally, we can run on less-than-perfect surfaces and are no longer limited to running purely on good drag-strips.

Now we've got our fingers crossed that our old race transporter will pass its MOT, 'cos we can't get the car and all the kit to the track without her!

Next time out. we'll be taking eight rockets. We'll be going for two runs at the event. Rockets can be swapped out very quickly, though they are a lot of work to build up. So we're going to get them all fueled and ready well ahead of time and just to a simple swap-over at the track.

You can see a vid of a static test (a really good one!!) one www.myspace.com/laffingasrocket.

Bio fuel is awesome

The last run showed us the disadvantages of cardboard as a fuel-grain. The high-density tubes we have wound for us are surprisingly strong when packed very tightly into the aluminium casing and the stuff burns fairly well. In the run before last, when we only properly lit two rockets, we made the 1/8th mile in 4.6 secs. There is one big drawback and that is the susceptibility to damp conditions. We’ve known for a long time that the cardboard grows and shrinks very noticeably depending on how it’s been stored. Even in apparently dry conditions like the workshop, tubes will not want to fit inside one another and the cut length will vary. We’ve resorted to keeping the tubes we want to use next in the living room next to the radiator. These tubes slide together nicely and retain their cut length. However, they pick up damp very quickly, even when inside apparently sealed assembled rockets. One day is enough to seriously affect the performance.

Other rocketeers have commented that the presence of moisture shouldn’t make a difference and the resulting steam should add to the rocket pressure. This doesn’t seem to be the case. Firstly, the damp prevents the rockets from getting up to temperature, making the ‘steam-effect’ impossible to achieve. Secondly, the rocket pressure is self regulating as the higher the internal pressure, the slower the flow of input gas. If the rocket pressure equals the gas pressure, no gas can flow. Pressure, while important, is not the only factor in performance. The more important factor is energy. A non-combustible such as water can only detract from energy production. It is the energy in the rocket that creates the internal shockwaves and generates the hypersonic flow at the nozzle, the higher the exhaust velocity, the higher the thrust.

We have now constructed and twice tested a rocket with a new fuel grain set-up. The rockets were loaded with concentric cardboard tubes as before and then filled with cooking oil and allowed to stand for 48 hours. We had already experimented with cardboard and oil to see how well the oil soaked in. It soaked thoroughly. We had also turned a blow-torch onto a soaked piece of cardboard and observed the oil boiling to the surface, so we were reasonably confident that we would have a ‘wick-effect’ inside the rocket. On the first test, the initiating firework detonated, rather than burned, and ignition failed. As we were set up with gas in the fuel rig, we ignited the rocket by putting a firework in from the nozzle end. This is not a satisfactory arrangement as it was reasonable to expect the ignition only to be partial. The rocket did light and went on to main input jet, only for us to run out of fuel in the rig.

Two days ago, we repeated the experiment. This time we did achieve full ignition and the rocket ran on full power for 6.5 secs. It was three or four times as loud as any rocket we had previously tested. The diamond shockwaves in the jet were more than double in size and there were more of them. There is no doubt (though we lack the measuring equipment to accurately confirm this) that the rocket was two to three times more powerful than anything we had previously tested. This indicates a thrust of 2-3,000lbs.

On inspection of the test rig and rocket, in situ, it was discovered that the test-rig endplates (10mm steel) were both severely bowed, and that the rocket end-caps had both moved by 5mm. In spite of this movement, the sealing system had held up as there was no blow-by and no damage to the rocket casing or end-caps. On dismantling the test rig, we discovered that all the input connections had been vibrated loose and the rocket nozzle, whilst still retained in its outer holder, had fractured.
The cause of all this damage could not have been internal pressure, as the input gas pressures has been kept to our test standard. The bowed endplates must, therefore, be the result of the intensity of the internal shockwaves having a ‘hammer effect’ on the ends on the rocket.

This rocket was more powerful than we could use in a set of four in the car. 8-12,000lbs of thrust in an 850lb car is too much for operation on a quarter mile strip.
We can, however, reduce the rate of input of N2O by various means and reduce power to a more useful and manageable level.

The implications of these experiments are that we can now overcome the problem of damp, as an oil soaked rocket will not be susceptible, and that we can produce as much power as we could possibly require.

We have given some thought to external damping devices to absorb the hammer effect on the rocket ends. Further experiments are now needed to tune the gas flow and to test shock-absorbers.

This rocket set-up has the potential (when constructed with superior materials) to be extremely powerful and controllable. I believe it could have significant military and aviation applications.

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30/05/07

07:05:42 am, by carolynne , 248 words, 200 views
Categories: Day to day

Four Rockets LIT, but No Power!

There's a new vid on youtube.com/laffingastv. You can see the last run there. It was disappointing in that we didn't get the power out of the rockets, but pleasing because we've finally cracked the problem of lighting all four reliably. Why such low power? We took the rockets apart and found considerable moisture in the cardboard fuel grain. We'd encountered this before and proviously dealt with it by keeping the rockets indoors, in the central heating, until the last moment. This time we'd built them well in advance and put them in the car, relying on sealing the nozzles and inserting some 'Timbilt' boot dryers (fabric tubes full of silica gell). Mistake!! The boot dryers are great at drying wet biking boots (highly recomended) but the gell was not able to overcome the moisture hungry nature of the cardboard. Result: very cold burn, no real pressure in the rockets and running out of fuel at half track. If you look at the previous run, we actually went a lot quicker on two rockets! You could see the diamond shock-waves in the exhaust jet on that run... no diamonds this time. This can only be owned up to as a mistake. Back to keeping the rockets in the house for the next run!!
We've also been experimenting with a much more powerful fuel grain... cooking oil! We've got one more static test to do to ensure the rockets can take the pressure, then we'll publish the results.

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19/05/07

06:33:16 am, by carolynne , 124 words, 116 views
Categories: Day to day

a.m. Saturday May 19th

We're getting ready to load up the transporter and take the car over to Shakey ready for tomorrow's run. We want to get back in time to watch the cup final, so it's a very early start. We've done as much as we can to ensure a full four-rocket burn... but as you all know, every time this car goes to the track it's an adventure into the unknown!!
We got another lovely email from Ky Michaelson, complimenting us on our 'good work' and wishing us luck. It means a lot coming from Ky. (For those who don't know, Ky built the Conklin Comet rocket car which is still the fastest thing ever in a quarter mile.)
So fingers crossed...the adventure continues
Carolynne

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09/05/07

10:41:55 am, by carolynne , 98 words, 164 views
Categories: Day to day

Full Pass on the 19/20th May

We'll be back At good old Shakey on the 19th and 20th, going for a full pass on four rockets. We're pretty confident it will all happen properly, but, as we're still testing - you never know!! Lots of new stuff has been done to get more reliable ignition with bigger better fireworks and flow balancing for the start-up. There'll be a film crew there to catch the action. You can see footage of the last run and of Carolynne explaining some bits about the car on youtube.com/laffingastv.
Please come along and support us!!
See you there!

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08/04/07

05:07:28 pm, by carolynne , 62 words, 129 views
Categories: Day to day

Contact Info

Unfortunately, we've had to make it more difficult to 'leave a comment' on this blog. After a series of trojan horses and sheer vandalistic attacks (sad isn't it?), access has been restricted. We still want to hear from you 'tho! So, if you want to leave a comment, PLEASE SEND IT TO OUR CONTACT INFO ON THE MAIN WEBSITE AND WE'LL RESPOND!!

Here wo go again!!

Having spent the off-season re-designing, re-engineering and re-wiring the car, we found ourselves at Shakespeare for the first test of the year. We were hoping for a quiet little testing day…so, I think, were most of the large number of teams out for their start-of-the-year shakedown. So it was busy and we were testing in public, again. (bugger!)

An all-new throttle control system has been installed which gives us full throttle control, (not easy with rockets!!) we’d gone up to 24 volt systems with capacitor discharge to fire the pyros (to avoid the voltage drops that plagued us last year) and generally applied all that we’d learned during last season. So there shouldn’t be any unknowns, right? Wrong! We had ordered the same fireworks as last year, opened the box and out came something completely different. They were noticeably smaller. We checked and double-checked and were assured they were the same. Oh no they weren’t, the manufacturer had changed them and our supplier hadn’t been informed.
It was now too late to go on the hunt for a more powerful substitute. So a new unknown was thrown in at the very last moment. AH the joys of Rocket Science!

The team is now a well-oiled machine, and the car was made ready and gassed up with no input from me. Glenn Stockton came along for his usual thorough scrutineering job and all the new systems were explained and demonstrated.

Serious butterflies in the old tummy as I walked down to the start, not because I was particularly worried about the drive, but very worried about the effectiveness of the pyros. A failure now would really hurt the project. They did struggle, only lighting three rockets. She still went like stink. So when we get four lit it should be an interesting ride.

I shut off just past halfway, as I am still learning about the car at speed and we promised to take it carefully. She really pushed hard, and the further and faster she goes the more she accelerates… quite the opposite of a traction car.

So a good, mostly successful, start to the year and, of course, we were delighted.

Now we’re working on some bigger and hotter pyros, the last link in the chain. Next time out? Hopefully we’ll get a full pass on four rockets. And that should be a very quick run!

After three very hard years, laffin-gas is showing what she can do… and it’s going to be a great show.

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15/03/07

10:04:02 am, by carolynne , 154 words, 114 views
Categories: Day to day

Laffin Gas supports HEADWAY

A note to let you all know that we will be supporting 'Headway', (the brain injuries trust) this year. My husband David suffered quite a bit of damage as a result of his many brain ops to remove a tumour. He attends the local Headway in Irthlingborough twice a week and it has been a fantastic help to us both. Recently featured in the BBC drama about head injury, Headway is a fantastic organisation that does wonders for people with life-changing injuries. The folks who attend are Members, not clients, and they are treated with great respect. As a carer, myself, the respite and knowledge I have gained from Headway has been vital.
So we'll we displaying the Headway logo on the car, and making the car available for Headway fund raising events during the year. I'm sure everyone involved in our sport will be happy to help us to help Headway.
cheers
Carolynne

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06/03/07

10:18:56 am, by carolynne , 138 words, 101 views
Categories: Day to day

"It's bin a long cold lonely winter".... and a busy one!
We've spent the time applying all the things we learned from last year's testing. A new throttle system now allows us to have full throttle control of the car and allows us to stage properly. All the control systems have been revised, replaced, upgraded and re-wired by Dave Rose and our new team member Andy Monk (see him in the 'people' section). So we're pretty sure that reliability will not be a problem this year and we can start to get some serious speeds out of the beast!
Geoff Martin and Buddie came round and re-certified the chassis, so we're SFI'd once more. A couple of private static tests are scheduled for March and we hope to be at Shakespeare on April 1st for a decent run.

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04/11/06

07:58:25 am, by carolynne , 128 words, 256 views
Categories: Day to day

Ky Michaelson gets in touch!

We've been lucky enough to get some emails from Ky Michaelson, the builder of the 'Conklin Comet', a rocket dragster in which Kitty O'Neil ran a qurter mile in 3.235 secs with a speed of 412mph. This was at the El Mirage airforce base in the Mojave desert. It's not on a dragstrip, true, but it is the fastest ever quarter mile... and done by a female.
Ky says " I've been building hybrid rockets since 1995 and I believe you are on the right track. You might even break Kitty's record". That's some record and certainly can't be attempted on a drag-strip. What a generous gentleman Ky is!
His website can be found a www.the-rocketman.com. I think this guys knows more about rockets than anybody I've come across.

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31/10/06

08:44:51 am, by carolynne , 366 words, 202 views
Categories: Day to day

Last Saturday we had more adventures! The difficulty with rockets is there's very little chance of a quick fix and another go. Once the fireworks in the heart of the rockets have gone off, they have to be replaced either with a second set of ready-to-go rockets or by opening them up, replacing the fireworks and rebuilding the rockets. All pretty much impossible when you're only out for a one-day test. With a less exotic car..it's often back to the pits for a quick fix and off you go again. With rockets everything simply has to work all at once.
The first problem we had was the failure of a very expensive special battery that powers most of the ignition systems. We backed the car off the line, nicked the battery out of Susie's little honda and checked all was working. Then (because the fireworks hadn't been lit and the gas had not been released (lucky!!) we had another go. This time she lit on the pilot gas. I pushed the throttle forward and the truly hefty throttle cable parted company from the throttle plate. I couldn't release the main gas. Attempt over!
Yes we were disappointed. But again we learned something. Each time we test we eliminate possible failures and, so far, we have never repeated an error. so it was all useful stuff!
Now the season is over and the car is being stripped down and fully reconditioned for next year.
I want to thank all the folks who've worked so hard. Firstly my brilliant team, David, David, Rachel, Susie and Vinnie, who have all kept motivated and positive and whose teamwork and good spirits have been a joy to be around. Thanks also to my dear brother Bob, who's helped with image, racing supplies and all kinds of 'connections' from his formula-one background.
Also a special 'THANK YOU' must go to all the people at Shakespeare County Raceway, for both their professional and thorough attention to safety and their generous support of our efforts. And thanks to all our fans!
The car may be going on display at some engineering and motorsport shows over winter. We'll keep you all posted.
cheers
Carolynne

'ere we go

The weather forecast has improved and all looks good for a run today (Saturday). It's a long drive in the race bus to get to Shakespeare from here. We've cycled and tested, gone over checklists and we're going for a good full throttle launch this afternoon. Staging is difficult for us as we have a long ignition sequence which can only just be made to fit in the 15 seconds that the lights allow. Even so we're going to try for a properly recorded run this time.

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26/10/06

08:40:23 am, by carolynne , 54 words, 136 views
Categories: Day to day

weather for Saturday's run

We've been watching the weather forecasts. As of yesterday it was 'showers Saturday, fine Sunday'. As of this morning it has changed to 'fine Saturday'. We're loading up the transporter and installing the rockets... but if it changes back to 'showers Sat' I'm afraid the test will be cancelled.
fingers crossed! Watch this space.

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21/10/06

09:18:24 am, by carolynne , 296 words, 122 views
Categories: Day to day

re-building the Rockets

Every time we do anything with this car, we learn something new. This time we learned that if you let the rockets sit undisturbed for a couple of weeks (after they've been run) they don't want to come apart!!
When a rocket tube has been used, it has to be stripped down to replace the fuel grains (cardboard tubes!!), the internal seals, and the firework that ignites the whole thing. This is when we get the chance to see how the construction has held up. There is always the odd little burn-through at the first line of defence in the seals, but, as usual, the second and third seal surfaces were intact. We also slice a fuel grain along its length to see the burn pattern. You get very little for the first 20cm, then very even along the rest of the length. Even the ignition wiring is burnt away and has to be replaced.
We normally strip the rockets down within a day or so of running them, but life had taken over and they'd sat for two weeks. Getting the end-caps off took a lot more effort than usual. Usually we can just drift the liners out, this time we had to set up a rig to winch them out of the ally tubes. Then we discovered that the same rig is ideal for installing the new liners...they went in tight and smooth. It's vital that the cardboard fits tightly to the outer case, or the gas pressure in the rocket will split it..and nitrous just loves burning ally!!
Anyway the rockets are built and sitting in the front room to keep the damp air away from them.
If any-one is interested in having a go at making rockets...get in touch...

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19/10/06

01:30:08 pm, by carolynne , 39 words, 1828 views
Categories: Day to day

Many many thanks must go to Matthew Augier of DPS for his great work on our website. The service has been friendly, quick and accurate. Any other racers..event organisers... traders..might want his link:
www.dps.uk.com

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12:16:25 pm, by carolynne , 72 words, 222 views
Categories: Day to day

Halloween run

Saturday the 28th of October will be our first full throttle test at Shakespeare raceway..
If you've got a little person with you, we'll try to give you a chance to get a pic of him/her in the car! (Depending on how busy the pit is!!)
There'll be a fireworks display, a huge bonfire, and lota of other great cars showing off. Check it all out at:
www.halloweenshowdown.co.uk/