Reusable spacecraft launch

[paulthebob]

Picture says it all.

How the F do you get this to work. Discovery did it in real life, so it is possible, but no matter what setup I have that looks anything like the real thing, the balance just throws this thing on its back.

Anyone ever done it?

[Read have Read]

One factoid I hear raised on the subject: KSP engines gimble 3 degrees while the space shuttle had 10 degrees of thrust vectoring.

[antiquark]

Real space shuttle has engines that can gimbal a lot. Therefore can always keep the thrust going directly through the center of mass. You can try a config edit to change the gimbal angle of your engines to say 20 degrees, it might make it flyable.

[paulthebob]

Has anyone ever succeeded in Discovery before?

[DerekL1963]

One factoid I hear raised on the subject: KSP engines gimble 3 degrees while the space shuttle had 10 degrees of thrust vectoring.

That and the Shuttle's engines weren't mounted with the thrust axis parallel to the body axis of the orbiter - they were actually tipped up (IIRC) 5 degrees.

[RawChicken]

There are youtube videos on Discovery on KSP, look for them.

This ships need lots of planning and tweaking.

[paulthebob]

There are youtube videos on Discovery on KSP, look for them.

This ships need lots of planning and tweaking.

I've seen the videos on youtube but none seem to have links to the mod and I can't find it on the spaceport.

Can someone tell me how to edit the gimbal settings please?

[Supernovy]

Find something that looks like this in the part.cfg for the engine you want to change. (found in Gamedata/Squad/parts/engines)

MODULE

{

name = ModuleGimbal

gimbalTransformName = thrustTransform

gimbalRange = 1

}

the "gimbalRange" parameter is the one you want to change, it's in degrees I believe.

[paulthebob]

Find something that looks like this in the part.cfg for the engine you want to change. (found in Gamedata/Squad/parts/engines)

MODULE

{

name = ModuleGimbal

gimbalTransformName = thrustTransform

gimbalRange = 1

}

the "gimbalRange" parameter is the one you want to change, it's in degrees I believe.

And so if I set that to 5 it will gimbal freely within 0-5 degrees per requirement?

[Supernovy]

Yes, though ASAS will still have a hard time, wibbling and woggling all over the place.

You may need an even greater gimbal range.

[Nibb31]

It's not just a thrust problem. ASAS and other flight computers can't cope with the off-center CoM. The whole physics engine isn't made for this.

[Rune]

Very careful design can get over this, there are a couple of decent shuttle replicas out there. But it's hard. And what you get in the end may or may not look like a shuttle.

Rune. Hint. CoM and line of thrust must be aligned during the whole flight. Otherwise, torque.

[stupid_chris]

The shuttle also had SRB's on the side. I believe they also had thrust vectoring (needs a check on that, I'm not quite sure) which would provide more stability by increasing the thrust on the lighter side. Then When they were dropped, the grav turn went in increasing tilting the shuttle on it's back and the big tank on top, which is done with less steering losses because the weight of the whole thing just wants to tilt that way anyway. So try orienting your craft so that the shuttle points east on liftoff, you'll have less trouble once you get to the grav turn.

[paulthebob]

The shuttle also had SRB's on the side. I believe they also had thrust vectoring (needs a check on that, I'm not quite sure) which would provide more stability by increasing the thrust on the lighter side. Then When they were dropped, the grav turn went in increasing tilting the shuttle on it's back and the big tank on top, which is done with less steering losses because the weight of the whole thing just wants to tilt that way anyway. So try orienting your craft so that the shuttle points east on liftoff, you'll have less trouble once you get to the grav turn.

This. But it's still far too unstable and the tilt made by the jets aren't possible in Kerbal. It's a feature that should be added I think, for these very designs.

[paulthebob]

Yes, though ASAS will still have a hard time, wibbling and woggling all over the place.

You may need an even greater gimbal range.

Even with 10 degrees, it still happened, just later on.

[Baron_von_Fluffy]

I think it's safe to say that the fact that Discovery type shuttles even get to orbit in the first place = a ton of props for the engineers that designed it.

[Colonel_Panic]

Better, more direct and kerbal-friendly solution: send up shuttles in pairs, with one on either side of the rocket for balance.

The problem you'll face in doing this the canon way is that while a shuttle in real life uses vectored thrust and specific flight characteristics of its engines and tanks to achieve bnoth balance and control, KSP simply isn't designed to make that kind of thing work. Even if you mod the engine gimballing range, KSP won't know what you're trying to do, to balance it out appropriately.

The only way to really make it work without excessive hackery, is to design your ship so that the total center of thrust is directly under the total center of mass, AND that both your shuttle and its rocket and tanks have pretty much exactly the same TWR curve on ascent (aka, your total weight on one side needs to drop at the same fractional rate as your weight on the other, while thrust remains constant on each... you can accomplish this by tweaking your engine efficiency and staging, and balancing your wet/dry weights one each side. It's extremely difficult.)

Or, you could just launch with a second shuttle to counterbalance the first.

P.S., make sure you ascend with your wings knife-edge up and down, or you'll get weird lift problems that will throw your rocket off.

[Nibb31]

What's this "Discovery Shuttles" denomination? The launcher was called "STS" (Space Transportation System), or "Space Shuttle". The actual spacecraft was the "Orbiter Vehicle", and each of the 6 orbiters had a name: Columbia, Challenger, Discovery, Atlantis, Endeavor, and Enterprise (which never flew in space).

Discovery was only one of them. If you really wanted to use a navy-style denomination, you would call them "Columbia-class".

[stupid_chris]

This. But it's still far too unstable and the tilt made by the jets aren't possible in Kerbal. It's a feature that should be added I think, for these very designs.

Hmmm, try putting tricoupler at the bottom of your shuttle, then fine tune tilt it outwards 5 degrees (shift+wasd tilts 5 degrees per tap) With some 5-10 degree gimballing engines it should do the trick. I think. It might be a tad bit harder to control once you're in orbit but It should be doable. I think.

[Specialist290]

What's this "Discovery Shuttles" denomination? The launcher was called "STS" (Space Transportation System), or "Space Shuttle". The actual spacecraft was the "Orbiter Vehicle", and each of the 6 orbiters had a name: Columbia, Challenger, Discovery, Atlantis, Endeavor, and Enterprise (which never flew in space).

Discovery was only one of them. If you really wanted to use a navy-style denomination, you would call them "Columbia-class".

It could be he's thinking along the lines of the old superstition that it's unlucky for a class of vessels to have a "flagship" that was lost in some kind of a disaster, much like how the Thresher-class submarines were all redesignated the Permit-class when the USS Thresher was lost at sea.

Under that logic, since both the Columbia and Challenger were lost in adverse circumstances, you could make a case for it being called the Discovery-class, since that was indeed the next-senior surviving vessel at retirement.

That said, I've never heard it called anything other than the Space Shuttle myself, at least before I joined these forums.

[1of6Billion]

There is a Space Shuttle pack around somewhere. It has a plugin that provides the necessary thrust vector. *brb

[1of6Billion]

Me thinks it was the Tiberdyne pack. But that has not been update for a while. Dunno if it still works.

[paulthebob]

Hmmm, try putting tricoupler at the bottom of your shuttle, then fine tune tilt it outwards 5 degrees (shift+wasd tilts 5 degrees per tap) With some 5-10 degree gimballing engines it should do the trick. I think. It might be a tad bit harder to control once you're in orbit but It should be doable. I think.

The game won't allow you to do the shift+wasd for engines put on the very bottom of fuel tanks.

@1of6billion -- any for 0.19? Or will that work in it?

[rhoark]

I've done a couple side mounted vehicles, closer to Buran-style than shuttle-style (the orbiter engines don't fire until apoapsis)

Method #1: engine toggling + fuel balancing

Method #2: engine on a Damned Robotics hinge

[paulthebob]

Cheers for that.

BTW the mod posted above is compatible in .19.

Still though, it should be a Kerbal goal to get side-mounted as a normal part of the game considering they probably made a large per centage of launches here on earth.