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!