Part 6, 23 September, 2005
By Mark Uitendaal and Leon Krancher

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Disclaimer: all liability waved! The contents of this page is presented for informational purposes only. Do not try to recreate any experiments presented in this page. The NAVRO and the author of this article cannot assume responsibility for any use readers make of this information. In The Netherlands it is forbidden by law to own this type of propellant if you do not have an exemption of the "Wet Explosieven Civiel Gebruik" (WECG).

Spectre II after a holiday

Before my holiday, I sent the camera-unit to Harry Advokaat, a NAVRO-member. Harry has the technology to solder SMD components, and he soldered two switches for external use to the camera. Many thanks Harry! This was done to switch the camera on and into AVI mode when it is installed in the rocket without having to take the whole rocket apart. After a good long holiday, we picked up the project with new and refreshed views. Quickly we transformed the old electronic canister into a new camera holding canister.

Some new fuselage components were made. This was done because the canister was slightly (10mm) larger then the old one, and a new mirror nacelle was to be attached to the fuselage. The lower fuselage and the fin section were left the same as well as the nosecone.

The mirror in the nacelle will have a 50° angle outwards, so we can still see the rocket body. This is done to record the staging manoeuvre in flight. Because the camera is above the drogue assembly, it will also record the separation and deployment of the drogue parachute. The main drawback of this set up is that it will record from drogue deployment to main deployment nothing but air and a parachute. The mirror is 20 X 35mm polycarbonate material, so it won't shatter upon impact with the ground. The mirror nacelle will be covered with glass fibre for extra reinforcement.

When this nacelle is in a high velocity fluid flow (like air on max q) the backside of the nacelle will create a low pressure area. This will interfere with our barometric sensors on the flight computers. We decided to program the PaDS on a timed recovery after barometric launch detection.

Motor developments:

We now decided to improve the inhibitors and replace the old paper tubing with 1.5mm cardboard tubing. The downside is that this design will have a total impulse of ± 1900Ns. This will be enough to power the rocket to 1300 metres, but not the intended 1400 metres. But it is still better to have a working motor, than to have a large CATO.

Success at last! The motor finally works! Unfortunately, due to traffic jams and a very busy schedule, the test was performed in complete darkness. This is the reason that there is no video footage available. The motor burned for a good 3 seconds, so the motor will probably be in the range of a K650 or so. Some thoughts will go into designing a new igniter to accommodate a rapid ignition. We have used 1 gram of black powder, but the full ignition occurred perhaps one second later. We think we can accelerate this with a better igniter design.

After the test, the motor was cut in half to see if casing was still structurally sound. There was no damage to the casing and no leakage. The nozzle was heavily eroded. We're very curious about the thrust curve, because there is some doubt about the nozzle efficiency.

We have also repaired our analogue static test stand. The balance was renewed and the overall construction was improved. Our launch box will have to be checked, but then we can make a new motor and perform an instrumented test.

We also are constructing a marriage jig for the booster. This jig will exactly align the set of fins to the fuselage.

We'll hope to update soon with a thrust curve!

Next part: Spectre II, part 7, 2 January, 2006

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