Flight Question Any Way to fire the shuttles main engines after e.t. separation

[Stevodoran]

just a simple question because you's all know the engines are fairly weak after e.t. separation and it would be great when trying to rendezvous with something

 

[garyw]

The main engines are fed by the ET. In real life the OMS engines have more than enough DeltaV to perform an ISS rendezvous + deorbit.

If you are having problems with the Shuttle you need to practice more as you are probably wasting prop on a plane change.

 

[Stevodoran]

thanks and i do use alot of prop on the plane change

 

[Urwumpe]

just a simple question because you's all know the engines are fairly weak after e.t. separation and it would be great when trying to rendezvous with something

No. in Orbiter, you could refuel the ET after reaching orbit and before separation, but that isn't reality.

In reality, you can only ignite the SSMEs once, and that only on the ground, because otherwise the ignition sequence would be out of rhythm. It does use electric ignition, but the thermal constraints and how the propellant flows into the engine during ignition sequence is very hard to adapt to space.

Also, you shouldn't overestimate the size of the payload bay - it could just carry enough propellants to start the engines and then initiate a safe shutdown. If you would let the tanks run completely dry, the turbopumps would overspeed and explode.

And DON't do plane changes- the whole OMS propellants of the Shuttle are just enough to change the plane by 1.5°, but if you need to change more than 0.1°, you are already wasting a lot of fuel. Launch more accurate and do plane changes as far away from Earth as possible.

 

[jinglesassy]

Launch more accurate and do plane changes as far away from Earth as possible.

I thought the closer to the earth the more fuel efficient plane changes were?

 

[Urwumpe]

I thought the closer to the earth the more fuel efficient plane changes were?

That is absolutely wrong. The Oberth effect is about orbit energy changes (RPe, RAp, SMa, ArgPe), but not orbit plane changes.

The formula for the DV for a plane change is always dv = 2 * v * sin(0.5 * ri)

The higher the velocity, the more dV you need.

 

[Sky Captain]

I suppose you could put extra OMS fuel tanks in the cargo bay if for some rason you had to reach higher orbit than normally possible. Hovever doing that in reality would likely recquire redesigning of OMS fuel system.

 

[Urwumpe]

I suppose you could put extra OMS fuel tanks in the cargo bay if for some rason you had to reach higher orbit than normally possible. Hovever doing that in reality would likely recquire redesigning of OMS fuel system.

Actually not. The fuel system is designed for pods in the payload bay, it just lacks the actual plumbing from the manifolds to the pods and the pods themselves. The cockpit and the computers still support such a tank, just the software does no longer do so.