From: Mark Blair AUSROC Projects 42 Broadmeadows Road Elizabeth North, SA 5113 Australia phone: +61 8 259 5316 (BH) +61 8 287 0078 (AH) email: mnb@dstos3.dsto.oz.au AUSROC UPDATE OCTOBER 1991 AUSROC II Update On the 15th September this year, the Ausroc 2 Lox/Kero regeneratively cooled rocket motor was test fired at the Ravenhall static test facility run by the Explosives Factory Maribyrnong in Melbourne. Despite some problems and rearrangements causing a 1 day hold to the firing and a procedural error in the pressurization system on the day, the firing occurred around midday. Data from the firing revealed that a thrust of 7500 N was achieved with a chamber pressure of 1.5 MPa and a burn duration of 20 seconds. The target for the trial was 10,000 N with a chamber pressure of 2 MPa for 20 seconds. After the tanks were reassembled from the failed hydro tests, their volumes were lower than required. In the prefiring calibration tests, the flow was set to last the full duration of 20 seconds. This obviously resulted in a lower than expected propellant flow rate and hence the low value of thrust and pressure obtained. From a post firing inspection of the motor, it was found that there was essentially no erosion of the chamber or throat and the aluminium injector face showed no signs of heat damage. The external temperature of the motor, at the inlet to the injector reached a temperature of around 90 C which was well below the calculated value of 140 C. This, however, could be attributable to the lower combustion pressure and, hence, lower heat transfer rate. The excellent motor condition after the firing led us to undertake a second static test without dissassembling the motor. To solve the low propellant flow problem it was necessary to increase the tank pressures. The regulators were adjusted, tanks refilled and a new igniter inserted. However, during the firing sequence at kero tank pressurisation, the seam weld in the tank ruptured spewing 30 lt of kerosene onto the ground. The lox continued to expell itself through the injector and chamber causing ice to form on the outer wall. As a result of this incident, there was no fire as the kerosene tank was safely located behind a steel wall away from the motor. The original idea was to have both tanks on a single rack but the safety officers of EFM decided to have the the kerosene tank moved to a safer location. A well justified move. In future firings we will have to put more effort into general safety issues. It is still not known whether the tank failure was a result of an imperfection in the weld or a fault in the regulator. The theoretical calculations indicated that the tank should have been able to hold the set pressure. Things will have to be checked more thoroughly in future trials. We are now in the process of manufacturing 2 new propellant tanks. This time we will be using 6061 seamless tubing instead of rolling and seam welding 5083. The 6000 series of Aluminium can be heat treated to increase its strength whereas the 5000 series cannot. When we originally designed the tanks we could not find the seamless tube in the right size (it isn't made in Australia). We have had to purchase imported tube and end cap material. Once the new tanks have been manufactured and tested we are hoping to conduct a second series of static firings to obtain the full rated thrust of 10,000 N. This requirement is essential for the flight trial. The firing sequencer and data aquisition system designed and manufactured by the AUSROC electronics group performed flawlessly and recorded much useful data. Fuelling procedures for the lox and kero may be changed as a result of experience gained during this first trial and activities should run a lot more smoothly in future trials. We would like to pass on our thanks to all those who made this firing possible with their support in material and/or kind. AUSROC III Update The student groups are now in the process of finalising their project work for 1991 and by the looks of some of the reports much research and design effort has gone into producing some manufacturable design concepts for AUSROC III. It looks like many, if not all, of the projects will be able to be carried over into 1992 and that some motor and structural hardware may be produced and tested in the same year. The projects contained in the AUSROC III program are too numerous to discuss individually in this update. In the last update we sent a copy of a tentative program for an AUSROC conference we are hoping to hold. This conference has now been confirmed for the 12-13th December 1991 in lecture theatre E5 in the Monash University Engineering Department. We are planning to have AUSROC team members/students present papers on the various projects making up the AUSROC III program as well as information on the AUSROC I & II programs. The projects for 1992 will also be discussed along with the goals for that same year.