Material Science (9/11/20)
Research Assessment #3
I began researching on a few fronts, one of which would be some new material science equations, or the Barlow;s equation and the other maths related to the material selection of a rocket engine parts. My source for this was Ken Mason, who pointed it out to me over an email.
There are a few things that made this engine more difficult than a normal regen engine but also easier in some other ways. So the ablative engine physically burns its inside liner at each firing to preserve its own integrity after the firing but it also manages to soak up almost all of the 5400 degrees F that this controlled combustion creates. The parts of this engine were the ablative liner, the converging section at the throat, and the diverging section which leads out from the throat and out the nozzle. And all of this is housed in a steel tube. Barlow’s equation states that the yield pressure is a function of the area and the pressure applied to an object and that leads you to know how much pressure a material can withstand. In this case we have a safety factor of about 4-5, which is overkill, but convenient. The ablative liner in our case is going to be phenolic canvas tubing as it is very good at absorbing heat and the steel pipe reinforces the whole mechanism and prevents it from bursting. In short, heat: Phenolic, pressure: Steel. We have come across only a few materials that would survive the length of this campaign, and those include fiberglass impregnated phenolic resin cloth also known as prepreg. It is some pretty nasty stuff and incredibly difficult to find and work with, but we found a proprietary replacement that works just as fine. The diverging section is going to be made out of silica-phenolic and glued in with a two part PVA glue so prevent the throat from flying out of the back of the engine from the 1500lbf of force that is being applied to it.
This gives me more of a perspective on the forces that act upon a rocket engine in addition to the nature of those materials used in an engine. Reflecting on these things, I think that there is a much greater value in mentors and catalogues and that is where I will be focusing my efforts. It was nice to find the materials that we need so we can properly machine and manufacture the engine.