Because of the structural failure at STF 4, most of the system fell down a 25 ft. flame trench. One of the few things that could really slow our project down to a crawl is having a damaged and unusable OXD tank (carbon-fiber with an aluminum inner liner). Because this was a big concern after the fall, a hydrostatic test was performed to verify the tank’s integrity. This is essentially filling the system with water and then pressurizing it to the pressure you want (in this case 2200 psi). We breathed a sigh of relief when we were able to verify the tank up to 2200 psi, which, since we operate at a pressure of 2000 psi, gives us a 10% margin. With this test under our belts, we are confident going forward with our tank.
There was a huge amount of work done on this subsystem last semester (Fall 2012) to get it to the state it is in now, which is a design freeze. One thing that was worked on was the main valve actuation (MVA) system. After weighing the options, a ground-based actuation system was decided on. Essentially this allows us to actuate the main valve (through which flow from the tank goes into the combustion chamber and produces thrust) and allow the rocket to take off without having to carry the excess mass of the actuation system itself. It is designed with flight in mind so that once the main valve is fully open, the rocket is able to take off. Below is a proof test that we did when we were first developing the actuation system.
Another thing that was worked on is the quick disconnect (QD) system also designed with flight in mind. The reason we need this is because we have a fill line (through which we fill the OXD tank with oxidizer) connected to the rocket. When the rocket is ready to launch, it needs to be disconnected so that the rocket may take off unimpeded. The video and pictures below shows how this system works.
With this subsystem working well from last semester’s work, it is in a design freeze.