Balancing a Space plane on a rocket

[Fifflethecat]

I tried recreating something similar to this:

When I launch, it starts to lean back because there is naturally less weight on that side. What can I do to balance it out?

Also, I use Novapunch to build the actual rocket.

[YoshiFan501]

there is a good space shuttle mod, you know.

[Vanamonde]

What can I do to balance it out?

On the real one, the orbiter\'s engines are angled slightly to help counter the asymmetrical weight, as you can see here. I don\'t know how well that would work in the game, but if you\'re trying to make something similar, that\'s how the real guys did it. Otherwise, more (asymetrically arranged) boosters!

[Fifflethecat]

there is a good space shuttle mod, you know.

I\'m aware of this but it wouldn\'t be as fun as building and balancing the shuttle yourself. Besides, if i\'m not mistaken, that is what the Mk3 pod is for.

On the real one, the orbiter\'s engines are angled slightly to help counter the asymmetrical weight, as you can see here. I don\'t know how well that would work in the game, but if you\'re trying to make something similar, that\'s how the real guys did it. Otherwise, more (asymetrically arranged) boosters!

Yeah if I would use the Shift + WASDQE function, i\'m not sure it would work correctly.

[togfox]

It\'s a really difficult thing to build - a shuttle on the side of a \'lifter\'. Difficult with current tools anyway - remembering angles are difficult to achieve and the throttle controls ALL liquid fueled engines - you can\'t control them individually.

I went as far as scattering RCS all over my booster so that RCS can help keep the rocket verticle. That didn\'t work. I even had a LFE attached HORIZONTAL at the nose. This means as the rocket tipped over I could manually throttle the horizontal engine so that the rocket stayed upright. Clumsy, looks aweful, but it worked. It also made gravity turns a piece of cake as the craft would slowly tip over as I adjusted the horizontal throttle down. =P The problem is that you need to boost/lift on something other than LFE because the throttle for LFE is dedicated to keeping the pitch correct. This means solid boosters all the way to low orbit!! YEAH BABY. Again. Not very attractive. I was using stock only.

It is an engineering nightmare - I have to admit.

[gmpilot]

I am very close to making a (stock) working one, it has a lot of little flaws and isn\'t the prettiest, but it almost gets the job done. I am trying to get the balance right for upper atmosphere (around 40km) boosting where fuel usage starts to make it unbalanced, with the tradeoff being no more liquid fuel for the rockets left. The shuttle performs fantastically when it comes to landing. Here\'s a pic, I\'ll see if I can take a video or something later.

[andyjfaulkner]

I stream space planes quite a lot and am infact starting the stream up now!

http://twitch.tv/andyjfaulkner

[Don_Draper]

I\'ve kind of given up on mimicking the NASA approach for now, I\'ve just went with a symmetrical rocket arrangement. I figure it\'s temporary until I can nut out a solution for a more authentic stack.

[fraczus]

You can do somethink like I did. It\'s working at least for me.

[zpox357]

I put the solid rocket boosters on the wings, but if its realism you are looking for its not really an option. You could try adding a small cluster of liquid engines adding up to the same thrust on the tail. Or you could try overloading it with RCS thrusters and RCS tanks (haven\'t and don\'t really want to try this)

[Bekiekutmoar]

One of my designs. Was a huge pain in the ass to get in orbit ...

[gmpilot]

I think some of you are missing the point here; putting a shuttle on top of the rocket is pretty easy, it\'s the piggybacking aspect that\'s difficult. We\'re taking lateral separation.

[Rockon]

I\'ve tried counterweights, usually a dummy copy of the main ship. It\'s difficult to perfect that, though.

[chrislo27]

This is really hard to do. I was talking with my dad about this the other day and RCS may help but there\'s no guarantees!

[Assassin_55]

try Damn Robotics with the Hinge

[Firov]

Honestly, I rather hate this design, as it's massively complicated to attach the payload in an offset position. Especially factoring in the limited benefits of this method. The shuttle, while very impressive and even iconic, was a huge boondoggle and waste of money.

Now, all of that said, I actually have been experimenting with true NASA shuttle designs with no ridiculous gimmicks like counterweights or SRBs on the shuttle itself, and as others have pointed out, there's only one way to really make it work, and that's by angling the shuttle's main engines so their direction of thrust passes through the center of mass on the shuttle stack.

Sounds easy, right? Not so much since your center of mass is going to shift as you consume fuel from your main tank. This means you'll either need to be a design savant, or you'll need some way of angling the engines in flight or at least controlling their thrust on an individual basis. You may be a design savant. If so, I'd love to see your shuttle design.

If not though there are two mods that will at least make this somewhat possible. Neither is going to make this easy by any stretch of the imagination, but at least it will give you the tools you need to succeed.

The first mod I found is the Throttle Steering. This mod will dynamically alter the throttle settings on the active engines based on steering inputs, both manual, ASAS, and Remote Tech. Probably Mechjeb too, but I don't use it. This is useful, as you'll be able to have the main ascent engines offset at an angle, as well as non-angled orbital maneuvering engines (OMS) and this mod will alter the thrust between the various sets of engines during ascent, effectively altering your center of thrust. Its a bit finicky, and requires a decent amount of babysitting, but I have been able to get a small conventional shuttle into orbit with this mod. A tip, have action groups set up to switch between the various engine clusters. During initial ascent, you'll probably need to shut down the OMS engines. Once your main tank is nearing empty, you'll probably need to shut off your main engines. Action groups will make that a lot easier. Also, while this mod is extremely effective, its not foolproof. You'll still need to finesse the throttle on the way up. I've also found its easier if the shuttle is in the ventral position position to the fuel tank during ascent. Which makes sense, as I believe the real shuttle maintains that position during ascent.

The next mod that will (maybe) make your shuttle aspirations a reality is Damned Robotics. Truthfully, I've not used this mod to make a shuttle (that's next), but it does include powered hinges which could act as an effective gimbal for your main engines during ascent. You'll need to manually adjust the engine angle all the way up, but in theory, this will allow even more control than the throttle steering mod. I've seen a few examples of people who do this, and it does seem to work pretty well. You might also be able to trim a bit of weight off of your shuttle with this mod, since you can remove the requirement for dedicated OMS engines.

Hmm, again I've been a bit too verbose in my post. I really need to work on that. Anyway, one final thing, don't think of these mods as cheating. I promise you. They won't make it "easy" to create a NASA style shuttle. They'll just make it possible.

If you do try to make a true shuttle, expect to shout "Abort to orbit! Abort to orbit!" at your screen a whole lot. Then again, I expect that applies to most things Kerbal.

Edited May 13, 2013 by Firov

[OneRedBlock]

A handy tip is to put the boosters on radial decouplers attached to the wingtips. The ship won't get into an orbit beyond 80km (usually), but it can get into orbit for refuelling.

[EndOfTheEarth]

The Space shuttle only works IRL because it has its engines gimbaled all the way back to account for the weight issue during launch. This doesn't happen in KSP.

A better approach would be something closer to the Dream Chaser design:

Gets to orbit and flies back, but the heavy weight at the top of the rocket means that you need to be really, really careful about stability and the gravity turn.

[automcdonough]

I agree it's more difficult than it's worth. Even if you get the mass dead-nuts centered, the counterweight has different part count/drag to cause it to fly as if the weight is still off-center. My best attempt had a wing attached to a long line of struts sticking straight out the side, looked silly.

[rhoark]

Vertically launching a winged vehicle is tricky, whether on top or on the side. A rule of thumb that's working for me with the vertical stack is whatever wings are on top, bigger wings go on the bottom. That helps the stability a lot. I'm planning to try a side mount soon by attaching engines radially to the core underneath the orbiter.

[sadron]

Not that I mind necessarily since it's still a relevant question, but what's with the thread necromancy? ;p

[Firov]

Not that I mind necessarily since it's still a relevant question, but what's with the thread necromancy? ;p

Unfortunately, the forum explosion has resulted in a lot of these. I wish I would have checked the original post date closer before responding. I just looked at the last post, which was today.

I imagine the original poster has long since answered this question or stopped bothering with shuttle designs. So my "help" wasn't that helpful. Oh well...

[SecondGuessing]

Find out the weight of your space-plane using engineer/mechjeb and then put an equal amount in fuel tanks on the other side of the main rocket boost. Don't connect them using fuel pipes.

[E. F. Kranz]

Believe it or not, at one point the shuttle was to be launched atop a Saturn variant.

http://en.wikipedia.org/wiki/Saturn-Shuttle

[leax256]

my only succesful rocket assisted spaceplane, 100% stock

The tank on the side opposite the plane is not empyied, it's counterweight.