Here is a diagram of the motor. The nos is used to pressurise the fuel tanks when the nos solenoids are opened. There is a piston in the tank to keep the nos and fuel seperate.
The starting sequence is:
- Spark plug on
- Open Starter solenoid valve
- Wait a second (optimum duration to be determined)
- Open Main solenoid valve
The propellant feed for the starter was too big and it took a while for the chamber to warm up enough to ignite the main feed. Even though the motor only burned for a few seconds, the o-rings were severly damaged. I bought some viton o-rings for the next test.
For a while now we wanted to make a spark ignited motor. One Saturday, Justin and myself came up with this design. I have finished the machining and will test this weekend (DV).
It is a regeneratively cooled motor producing 80N of thrust. It runs on petrol and nitrous oxide. The nitrous oxide flows around the outside of the combustion chamber to cool the motor. It was designed to run on gaseous nitrous oxide.
There is a seperate nos and fuel feed for the starting the motor. The startup sequence will be: start the spark, start the flow of nos and fuel (.25mm fuel and 0.5mm nos injectors), then start the main motor flow (0.5mm fuel and 1.2mm nos injector)
Here is a photo of the combustion chamber (before anodising) and the sleeve.
Here is my assisntant and quality control oficer holding it for size reference.
The Combustion chamber after anodising.
The motor mounted on a box for testing. The solenoid valves, fuel tanks, coil and battery will go into this box. It just makes it easier to carry everything around.