By Benjamin Wilkosz
Part 4, 1 March, 2006
- Terminal Velocity, part 1, 23 December, 2004
- Terminal Velocity, part 2, 16 February, 2005
- Terminal Velocity, part 3, 27 April, 2005
- Terminal Velocity, part 5, 28 April, 2006
- Terminal Velocity, part 6, 12 March, 2007
- Terminal Velocity, part 7, 9 October, 2007
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).
After some months of stagnation, I finally found some time to work on my Terminal Velocity project. To propel the rocket I decided to give the sugar Avalon motor series a last chance. To solve the erosive problems I decided to use sorbitol, which has a significant lower pressure exponent at the designed operation pressure. The aimed operation pressure is 3,0Mpa. This pressure is chosen to minimize the stress with a very acceptable specific impulse. In combination with the fact that Sorbitol/KNO3 propellant has a pressure component near zero between 1,8 and 4Mpa resulting in a system with a very nice characteristic, it is dynamically stabile. Of course only as a first approximation. Erosive effects, which will be significant with the Avalon008 design, will be investigated and maybe simulated. Next, this propellant will provide a flatter thrust curve. Also, the casing will be more labour intensive, due to the cold-anodisation used to make the casing easier to clean and overall a surface which is more resistant to the hot and aggressive gasses produced during burn. The nozzle is redesigned to optimise the weight to impulse ratio. The thin wall forced me to use a high carbon steel (Ck 45) for the nozzle. This hard material is difficult to machine, but delivers a light high quality nozzle. To ensure the hardware will survive a CATO, during static test or flight, the forward is modified with a weakest point, calculated to blow out most of the forward at a pressure of 10Mpa. The new Avalon008 will be tested on the hydraulic test stand.
As for the airframe, both the upper and lower part are laminated with three layers of 160gr/m² glass fibre. The fins are laminated with two extra layers of 200gr/m² carbon fibre to withstand the high aero dynamical stress during near supersonic flight. All bulkheads are made of aluminium to ensure their functionality during high loads.
Next, I made the decision to install an AED Electronics igniters expansion board in the electronics bay of the Terminal Velocity instead of a second Trax-Art. This gives the possibility to use two more igniters (for backup or other further systems) instead of one. Furthermore, unfortunately, the production of the Trax-Art with G-switch is stopped.
The Terminal Velocity will be equipped with a video module in the nose cone. To provide a larger transmitting range, the camera will be extended with a external amplifier of 800mW. This will be a large improvement to the initial intern 10mW transmitter.
Still, there is a long way to go before the new Avalon008 will be "on line". Hopefully I will be able to test the motor around April and maybe open the possibility to launch the Terminal Velocity in August 2006!
Next part: Terminal Velocity, part 5, 28 April, 2006