History was made on of Friday the 25th of March and a new era begun for DARE as the DAWN hybrid propulsion team made the first successful ignition of a hybrid engine within the student society. It also marks a great step forward in the development of the hybrid motor for Project Stratos II, DARE’s flagship project.
Previous tests from DAWN have been focused on testing particular subsystems such as the injector, feed system, pyro charge igniter and electric igniter. This test was unique because it was the first attempt to demonstrate that all the subsystems could be integrated and function as an engine.
The DAWN team had planned to conduct this test much earlier, but due delays in receiving the required permits to handle dangerous substances, all tests were put on hold. This was the case until the idea was hatched to use a new type of igniter, one which requires no restricted chemicals such as black powder or conventional solid rocket fuels. The idea was to use a resistance wire to heat magnesium ribbon to its auto ignition temperature, causing it to catch alight and in turn ignite the engine. Once this concept was proven viable in tests, the motor test could go ahead.

The DAWN team put in an intense week of late nights and early mornings to get the test ready, but come that Friday morning, everything was organized and ran like clockwork. The motor was ready, and so was the team. The countdown started. 3..2..1..ignition sequence started..3..2..1..valve open and ignition! The motor spewed smoke in every direction, enveloping the small crowd that had gathered in smoke. It was clear that not quite everything had gone exactly as planned. But  after about 7 seconds, the nitrous was turned off and the bystanders applauded. Despite the obvious problems they knew it was still a success for the DAWN team.
On closer inspection of the video, it’s quite clear to see that the motor couldn’t handle the heat and pressure of combustion, causing it to fail after 6 seconds or so of burning. After only a few seconds of burning, the rubber O-rings can be seen to creep out of place, causing the leaks to worsen. This leaking resulted in hot gases flowing past the sides of the tube and the endcaps, which eventually caused a piece of the combustion chamber to be torn out.  Unfortunately, this makes the test motor unusable. This doesn’t worry the DAWN team as this motor has served its purpose and will be redesigned to ensure that the next test will feature more than just successful ignition.

Connection of the ignitor wires

There were two sensors connected to the test bench. One was a load cell that measured the weight of the oxidizer tank. By looking at the change in weight of the tank the team hoped to retrieve information on the nitrous flow. However, the sensor did not produce any useful readings as the changes in the weight of the tank seem to be lost in the noise due to the settings of the data logger.
The second sensor on the test bench was a pressure sensor that was connected to the combustion chamber, next to the injector. The pressure sensor can also be seen in the video. Some nice readings were obtained from this sensor. The pressure graph clearly shows a nice increase in pressure as soon as the engine ignites. The pressure in the combustion chamber then holds fairly constant until after approximately three seconds when the O-ring near the injector fails. Then the pressure drops significantly. After this, the pressure is again fairly constant until the end of the burn, approximately another four seconds later. A full analysis will be posted when all the data has been gathered and analyzed.

Pressure data of the first hybrid motor

To conclude, this test has laid the foundation of a successful motor concept, which can eventually be made into a flight motor for Project Stratos II. Although there is certainly a lot of work still to be done, this recent success will drive the DAWN team to push on to the next goal. The coming weeks are sure to be an exciting time. Watch this space!