New Team Prometheus Team Member

i don't care what the gas is, i'm using ideal gas law. and speed of sound doesn't matter i'm not sure where you thought i was using that. basically i'm doing the simplest possible assumptions you can make to model a gas gun: a lot of pressure in a small volume, expanding into a larger volume and hence propelling the projectile. in the first i assume this expansion is isothermic (constant temperature), and hence the dependent constant is nT, number of moles of gas * temperature. next i assume it is isobaric (constant pressure), in which case i calculate the required pressure to get the necessary velocity upon exiting the gun.

i take force = area * pressure, then calculate delta-E (for first case), or delta-V (for second case).

Well, I used some software that was handed down to me from a friend of a friend that built the Rice University LGG and I went with that. There gun hit 7.5km/sec. and just looking at it the numbers looked ok to me. No I did not check it manualy so are you interested in the data?

Monroe
Team Prometheus

o if you used software i'm not going to dispute your results, the model it uses is undoubtedly far more accurate than my crude calculations. i got the right order of magnitude for the pressure so close enough. just one more question though- i'm not too familiar with shock but it seems like there would be a good chance you'll have to do something clever to keep the electronics stable after being shot out of a super powerful gun like that. or is that not a concern?

Well you can epoxy everything to stop chips coming apart, but that adds to the mass of the sat.

I don’t believe any electronics can survive near a million g's. My idea is to have a very elliptical orbit and watch for Re-entry along the line of fire and hope it re-enters at night. Because most shooting stars are very small (grain of sand) and don’t have an orbital trajectory. Our re-entry would have a very long tail. It is the N-Prize you know and it has to be cheap and dirty.
Monroe
Team Prometheus

Well you know how I am planning on keeping my first stage on the ground...

- FAS