Space Shuttles

[peadar1987]

So my current challenge is building a partly reusable vertical take-off space shuttle.

I can get it so it is balanced with two SRBs on the external fuel tank and the orbiter engine firing at the same time, but when I jettison the SRBs, I have the problem of off-centre thrust. How do people deal with this, and stop your beautiful shuttle cartwheeling into a fireball? Is it simple a matter of rolling the craft onto its back and choosing the right pitch angle so the off-centre torque from the engine is cancelled out by the tendency of the craft to topple under gravity? In that case, I have a whole new-found respect for anyone who was able to pilot that thing!

Edited November 25, 2013 by peadar1987

[Camelotking524]

As you can see in this pic, the main engines on the orbiter are angeled through the center of mass. Along with using large SAS systems to help balance the setup and the correct roll angle, you should able to get the Orbiter into orbit.

Unless you are doing the challenge with stock parts only, I would recommend using Klockhead Martian's shuttle engine mod. Its engines have a large gimbals along with having a pivot point that will allow you to switch from an angle to straight.

http://kerbalspaceprogram.com/space-shuttle-engines/

Otherwise, its a matter of testing the correct angle with the stock engines.

[Zephram Kerman]

Well said. All I can add is to visualize (sorry I have no diagram for this) the two thrust axes going through the center of mass. The IRL shuttle SRBs burned out long before the external tank was empty, but they did gradually slow down to sortof match the decreasing fuel mass. Our SBRs don't do that, which is why you need a lot of control authority.

If you can scale the thing so that the external tank is just one orange jumbo tank, that would make it relatively much easier, since the tank CoM wouldn't change.

A project like this really does increase one's appreciation for real rocket scientists.

[Kosmo-not]

Difficult, but possible. Here's a video to give you hope:

[Skyrunner27]

You could always launch your shuttle Dreamchaser style.

[Rabid_Monkey]

Here's a video to give you hope

That. Was. AWESOME!

[Tank Buddy]

You would either have to design it so that you cut an engine that previously balanced it out, or add another to turn on and re balance the center of thrust.

[peadar1987]

As you can see in this pic, the main engines on the orbiter are angeled through the center of mass. Along with using large SAS systems to help balance the setup and the correct roll angle, you should able to get the Orbiter into orbit.

Unless you are doing the challenge with stock parts only, I would recommend using Klockhead Martian's shuttle engine mod. Its engines have a large gimbals along with having a pivot point that will allow you to switch from an angle to straight.

http://kerbalspaceprogram.com/space-shuttle-engines/

Otherwise, its a matter of testing the correct angle with the stock engines.

Awesome photo, thanks!

The main problem with my orbiter is the sudden change in the centre of thrust whenever the SRBs cut out, angling the orbiter engines and the SRBs inwards would definitely help with that. Then I can stick on secondary engines aligned with the orbiter centre of mass for circularisation after the external tank is jettisoned.

[el_coyoto]

Plenty of solutions for this interesting engineering problem, as said before.

I've also seen someone build the shuttle orange out of several smaller tanks with as many fuel pipes leading back to the shuttle, draining the fuel more evenly without human intervention. It's a smart solution, but it looks like, well ... yellow ... and spidery.

Another neat trick I saw was building the shuttle engines by sticking one central engine, and in 3x symmetry attached 3 more engines around. Therefore, during ascent, the guy had the following choices of engines to deactivate/reactivate to move the centre of thrust :

1. the central engine

2. the engine aligned with the centre of thrust of the 3x symmetry group

3. the remaining 2 engines of the 3x symmetry group

(I wish I could find images of it to make it clearer)

(3)   (3)
  /---\
  |(1)|
  \---/
   (2)

By choosing the right engines at the right moment, his stock Shuttle flew perfectly even with the big tank still attached and draining (he combined this with the first trick if I'm not mistaken)

The engines trick impressed me so much that I might build a pseudo Space Shuttle just to implement it!

You can also download/edit engines with a much bigger gimbal range : just like the real one, this should help with the shifting centre of mass. (if I remember correctly, the shuttle engines had a 10° gimbal range and I've seen people editing stock engines up to 30°)

Edited November 22, 2013 by el_coyoto
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[Tex_NL]

You could always launch your shuttle Dreamchaser style.

Slightly off-topic but don't you mean Hermes style?

The Dreamchaser isn't an original concept. It started early this century while the ESA Hermes project was canceled in the early '90.

[Camelotking524]

Slightly off-topic but don't you mean Hermes style?

The Dreamchaser isn't an original concept. It started early this century while the ESA Hermes project was canceled in the early '90.

Well, if you want to be technical like that. Wouldn't it be Dynasoar style.

Also, I'll get a picture of a shuttle using the space shuttle engine mod, so you can use them for an example.

[Tex_NL]

Well, if you want to be technical like that. Wouldn't it be Dynasoar style.

http://upload.wikimedia.org/wikipedia/commons/f/f4/Dyna_Soar_launchers.png

Also, I'll get a picture of a shuttle using the space shuttle engine mod, so you can use them for an example.

I stand corrected. I did not know about that one.

I did some background checking on that thing and it looks like it was greatly ahead of its time. A 'Space shuttle' even before the first moon landings.