Is it possible for a rocket to go faster than its propellant exhaust velocity?
SpaceX seems to do perform a form of full vehicles integration testing when it performs the static fire tests. Obviously they can do this at little expense due to the fact that their engines are restartable and relatively reusable. Obviously this type of test cannot be performed with rockets that can only be started once. It seems like a pretty valuable test to me. I was wondering how any other launch systems are tested in such a way?
I'm trying to calculate the Tsiolkovsky delta-V for a parallel stage like the Space Shuttle with greatly different ISP. How would you calculate the "effective" ISP for that kind of arrangement?
Isp is a ratio of prop consumed
Quote from: MP99 on 08/28/2014 07:59 amIsp is a ratio of prop consumedjust to clarify... it is mass/weight consumed, not volume
Quote from: aga on 08/28/2014 08:40 amQuote from: MP99 on 08/28/2014 07:59 amIsp is a ratio of prop consumedjust to clarify... it is mass/weight consumed, not volumeImportant addition to the original sentence is per unit of time ie. thrust divided by mass flow rate.For n different engines firing simultaneously with thrusts F1, F2 ... Fn and respective specific impulses of Isp.1, Isp.2 ... Isp.n the math isIsp.combined = ( F1 + F2 + ... + Fn ) / ( F1 / Isp.1 + F2 / Isp.2 + ... + Fn / Isp.n )
You don't need to send ships out to fish the capsule out of the water, and you have much less chance of seawater leaking in.
Also, the thrusters don't really add complexity since they're needed for abort. Also, parachutes have a way of failing. Powered landing can be done with parachutes as a backup.
Soyuz has had partial parachute failures