I made a plane, it flies fine, but when I try to land it spins out of control. help?

[jamgoth]

Are there any mods which could help me control the plane while only using stock parts.

[Vanamonde]

Pictures of the craft are necessary for a proper diagnosis of the problem, but from what you're describing, I suspect the balance of the craft is shifting as you burn fuel.

[capi3101]

Going to direct you to DocMoriarty's guide; it's in the process of being updated for 0.25 but the principles remain sound. Vanamonde is right, though; it sounds like your CoM is shifting aft as you burn fuel and it's going far enough that your final CoM is behind your CoL, which makes your craft unstable.

I had a craft like that circa 0.23; ultimately I redesigned it to include a "ballast" system using one quad of full RCS cylinders aft and one empty set up at the nose. Upon reaching orbit, I'd shift the fuel forward. Did the trick but boy was it a pain. Alternatively you can set all your fuel tanks parallel to one another; that should make it where the CoM doesn't shift as much but building the craft may become problematic depending on its size.

I might also recommend installing RCS Build Aid. It will show you a "dry center of mass", i.e. where the CoM will be when your tanks are dry. It's handy for spaceplane construction for that very reason.

[CDK]

I think that happened to me once too. Once it was my favorite plane but than, it was a weird plane. Very, very odd indeed.

[Alshain]

Going to direct you to DocMoriarty's guide;

Wow, that is an incredibly long winded guide. I think Keptin's guide is a little more beginner friendly.

[capi3101]

Wow, that is an incredibly long winded guide. I think Keptin's guide is a little more beginner friendly.

True. Keptin's guide is a good explanation of the basics and a great place for beginners. DocMoriarty's guide is more for when you're ready to start making your planes actually do something; I find it helpful for the hard numbers it gives on certain parts.

[The_Rocketeer]

My top tip:

Make sure to add an in-line reaction wheel and fly with SAS turned on - makes any plane far easier to control, although your plane will need help when banking as the SAS will try to hold it flying straight ahead.

[Kryxal]

I'm wondering at what point in the landing process it spins out ... for that matter, what sort of approach are you trying to use?

[Mystique]

Can you land it anywhere on even surface, not aiming for runway? Maybe you're also overcorrecting during final phases of approach, when speed is small and it's easiest to stall. Try just flying directly forward and gently landing somewhere in grasslands, at least for practice reasons.

[herbal space program]

Short answer, 90% probable to be correct: you got too much junk in the trunk because all the fuel is gone from your nose. As you fly, the program takes fuel from the tank farthest from the engine first, which is usually the one in front. As this happens, your center of mass moves steadily backwards. Once it creeps behind your center of lift, your plane will only want to fly bass-ackwards. Either pump fuel forward during your flight or redesign so that the fuel drains in a more balanced way using fuel lines etc.