By Benjamin Wilkosz
Part 2, 6 May, 2008
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).
Static test of the Avalon8+
At the 26 April I tested the Avalon8+ with the new nozzle design. The new nozzle provides the solid booster with a Kn between 230 and 250 with an expansion ratio of approx. 7. To lower the hardware costs a new alloy for the casing was used: AlMgSi0.5. Analytical calculations showed that this material would withstand the tensions during a normal run of the Avalon8 and the casing design proved to be very rugged during earlier runs at which the nominal pressure in the combustion chamber was much higher than expected (up to approx. 200bar). The weather was fine during the test day and preparations went according to plan. The Avalon8+ met the aimed impulse increase of 200Ns with a significant shorter burn time than the original Avalon8. The higher chamber pressure and larger expansion increased the specific impulse up to 120 sec. The new Avalon8+ delivered a total impulse of 3200Ns with a peak thrust of 1100N. A effective burn time of 3.5 seconds gives this motor the rocket motor classification L900. The hardware survived the test without a scratch. The snap ring grooves did not show any signs of deformation and the single Viton O-rings at the nozzle and forward proved to be very reliable, not only under very high temperatures, but also under high pressure. Especially since the Viton O-rings were also used during the previous test. The pyrogen body installed in the forward closure also did not show any signs of leakage. This last test makes the Avalon8+ deliverable for future flights. Below is the video and to the right is the thrust curve of the test. The thrust curves of the original and upgraded Avalon8 are compared with each other in the graph.