General Question Specific Impulse (I_sp) for DG and Shuttle-A?

[Delta_Glider]

Hi Orbinauts,

I am doing some practice flight planning from first-principles, i.e. using my own calculations with a python script and not punching numbers into MFDs.

Looking at the ideal rocket equation, I'd like to know the specific impulse of the main engines of the DG and Shuttle-A, and how they vary with atmospheric pressure. I cannot seem to find this information in the reference documents. Can anybody point me in the right direction ?

Cheers!

 

[N_Molson]

It is very high, way above anything we have today, even ion engines. What you can try, as an experiment, is to load say 100 kg of propellant into the vessel, and, from a circular orbit, see how many m/s you get from it burning prograde or retrograde.

Alternatively, Orbiter is now open-source, so those numbers are somewhere in the SDK files.

 

[diogom]

From DeltaGlider.h:


Also, have you checked out section 1.5 of the API_Guide? (Orbitersdk/doc)

 

[francisdrake]

The answer is pretty good in sight.
ISP = 4e4 =40 000 m/s, or if you want it in seconds: 40 000 / 9,81 = 4 077 s.

 

[Delta_Glider]

Also, have you checked out section 1.5 of the API_Guide? (Orbitersdk/doc)

Perfect, thanks, that explains it well. I had not looked at any documents or files in the Orbiter sdk folder.