Impossible takeoff with spaceplanes

[edemapolmonare]

Hello everyone I am a new forum member but i play ksp since o.17 release; well, I have trouble taking off with spaceplanes, in detail:

in spite of my models have a good lift and a perfect symmetry, during take off,even at low speeds, models tend to deviate to the left or right, and eventually explode or spilling on one side. the only way to take off is put the aircraft on a platform. Observing aircraft during takeoffs I have seen that the landing gears tend to bend, despite attempts to block them with support elements. This problem manifests itself not only with Landing gears introduced by mods (B9 aerospace, firespitter), but also with stock's LG. does anyone know how to fix this? is a very frustrating situation, because of this problem have already left the game several times I hope someone can help me.

[TechnicalK3rbal]

Make sure the landing aren't canted (tilted) to either side. I had this problem too, and that fixed it.

[700NitroXpress]

You also might want to add struts to the body and make the planes more ridged. If the aircraft is flexing then that is tilting the landing gear, or if you don't have landing gear supporting the center of the plane, then it can also flex a little and this tends to cause the problem. If these solutions don't work, you might also have control surfaces that aren't aligned properly with symmetry. You can check this by having the breaks on, on the runway, then push the WASD keys and see how the control surfaces react. If any of them bend in the opposite direction of the other one, then that's also an issue.

Here's an example of the strut solution:

Here's an example of perfect landing gear for this plane:

Edited January 9, 2014 by 700NitroXpress

[edemapolmonare]

I tried both solutions, but the problem persists. I made sure that the models were very rigid, and straight landing gears, for now, the only solution was to apply two pairs of LG (front and back), but it is good only for large aircraft, for small planes, Having regard to the limited space, I have to opt for a tricycle gear configuration, and with only a few models can complete a take-off. what seems strange is that the landing gears despite the apparent rigid, during "rush" on the runway, they seem made ​​of jelly also coming to bend 45 degrees

[Soda Popinski]

Pics might help diagnose the issue.

[Vanamonde]

It sounds like your plane might simply be too heavy, edemapolmonare. Have you tried mounting additional landing gear to distribute the load?

[Markus Reese]

Myself for heavy craft, two things I do. One I do for all planes. Have wide spaced pivot gears.

Second for heavy lifters is to avoid placing gears on extensions, and if you do, make sure you strut them. I also double up, or quad up my landing gears if really heavy. Usually I have side by side, or if front to back, I rotate the rear one around.

[Andon]

All of my planes turn to the side on the runway (And it seems, only the runway). The gear leaning I've only encountered when the plane was too heavy or when the gear was angled funky.

[Lone K.]

Pair up landing gears (instead of 3 or 4 put 6 or 8 respectively, 2 in (about) the same spot as the single landing gear). Landing gear pairs tend to be more stable than single landing gear parts.

Either or your craft may be nose-heavy. Pics would surely help.

[Kitspace]

I am having the same problem with crafts with very high takeoff and landing speeds that at some point have not enough lift to take off but already enough to become hardly controllable on the runway.

[Heagar]

One reason can be, that the front landing gear is at the same height or even more than the back landing gear.

Make shure, that your front landing gear is lower, the space (height of a wing) is enough for that to accomplish. Witch is especially important with heavy loads, when your spaceplane is deformed after the physics is loaded.

Why this is an issue in KSP i can't say. But after intense testing i build every plane in a way, that it is slightly pointing "nose down" when it stands on the runway. Since then this "dancing" of the plane when it reaches about 30-50 m/s is gone.

[Wanderfound]

If it's turning on takeoff, there's something wrong in the design. Tricycle gear, high-nose gear, minimal part count gear; these all work if you do them right. Have a poke at my design thread linked in the sig; there are diverse gear arrangements there, and they all run straight (please ignore the D7 Heavy X5, though; that thing is a horrible kludge built when I didn't know what I was doing).

As mentioned above, screenshots would be a great help in diagnosing the problem; we can't operate in the dark. Preferably from above and the side in the SPH with the CoL/CoM indicators on, as well as some on the runway just as it starts to go wrong.

And, just to get the obvious out of the way first: have you unlocked the steering and disabled the brakes on the front gear? If not, do so.

Edited September 8, 2014 by Wanderfound