SSTOs and RCS blocks (Heat question)

[ayana]

Is there anything I can do to keep RCS thrusters from exploding during ascent/reentry? Or is it just a matter of luck?

[worir4]

You can try reenter with a more shallow angle to reduce the heating effect. (Increase periapsis). Assuming it is a space plane, you can also try different ways of pointing your plane to the atmosphere, try shield the RCS blocks from the flow.

[xtoro]

You can try using the place-anywhere RCS thrusters. They have a lower profile so it may help. Just make sure you cover all rotations when you place them.

[ayana]

You can try reenter with a more shallow angle to reduce the heating effect. (Increase periapsis). Assuming it is a space plane, you can also try different ways of pointing your plane to the atmosphere, try shield the RCS blocks from the flow.

Reentry works, at least. But during the ascent there's not much room for choice.

You can try using the place-anywhere RCS thrusters. They have a lower profile so it may help. Just make sure you cover all rotations when you place them.

Part of the problem is heat bleeding into them from other parts that tolerate the heat better, so this has issues too.

[Wolfox]

Unfortunatelly there are no aerodynamically shaped RCS blocks yet, so occluding them from the airstream is the only way. To achieve this, you can:

1) Place them on the top side of the craft and entering belly first. Not the best, as you mentioned, this doesn´t stop the heat from other parts to bleed into them, but its still better than being exposed directly to the airstream.

2) Place them in the bay. Don´t forget to open it before use of the RCS or else it may cause problems.

3) Use reaction wheels.

4) Use vernors. They run on Liquid fuel, so no need for extra monopropellant cans, and are much more aerodynamical than RCS thruster blocks.

Ascent isn´t usually as fast as reentry, so the main problem tend to be when entering. BUT, when you are returning, control surfaces will work again and (if your craft isn´t relying on the RCS to actually fly straight) then you might not need them anymore. Of course, with exception of SSTO, which have to deal with ALOT of heat during ascent, then i suggest using one of the above mentioned methods.

[ajburges]

Check your profiles.

If they overheat on ascent, you are spending to long to low. Check your ascent path. You want to hit max airspeed then use aerodynamic flight to start a climb to initiate a gravity turn to orbit. If you go beyond max thrust speed, climb faster.

If they overheat on reentry, you are coming in too steep. I have yet to see any orbit with a Pe of 45 km leave the atmosphere again. That is your baseline reentry profile. You never use a intersecting trajectory to reenter atmospheric worlds. That is a waste of fuel and won't even buy you much time.

RCS blocks hit 70% of critical temperature on reentry for me. That isn't even concerning. Only worry when the heat bar is red (85% of critical temperature)

[Sharpy]

I've never had any heat problems with Vernors. The rest of the plane would explode from heat and the vernors would splash down.