What is wrong with my plane?

[randomredneck]

Spaceplanes continue to befuddle me. I finally designed one that gets off the ground, but it just flips over or spins out after a couple seconds.

http://images.akamai.steamusercontent.com/ugc/269465369190995071/A393E1C9A84343C731455440D28707E7231D4BC0/

http://images.akamai.steamusercontent.com/ugc/269465369190995593/3FE8C686298BC3F478E46D6F9D060CD0A5ADFE26/

 

What am I doing wrong here?

[Reactordrone]

Well at the moment the only control you have is the butterfly tail and that's quite close to the CG of the aircraft which will limit its control authority. You could try moving those delta deluxe winglets to the rudder or tailplane position and add elevons to the wing.

[AlamoVampire]

<rubs the back of his head before speaking> If you would like an honest, nothing held back response, then, here ya go:

1. You have 0 viable control surfaces on your wings, they move counter to what you need from valid ailerons. You need up/down motion from them that runs along the trailing edge in parallel of your wings, not the current configuration.
2. You have an extra bit of fuselage at the end of your craft, from what I see, its not needed.
3. You have 0 horizontal controls at the aft (rear) end of your plane. While, YES, a V tail can work, the control surfaces you have on your plane lack the deflection force needed to control horizontal (roll down the central line <tip of nose to tip of tail>, Lateral roll  (yaw or left/right side deflection, think turning a car on the road that is yaw-like) or pitch (up/down).  
4. Your wings look as if they are not around the Center of Gravity of your plane which will make it highly unstable, not to mention you have a rather extreme dihedral angle (as in, you do not need THAT much angle on the wings) which may cause further instability in the aircraft.

Now, just so people do not think I am being mean, I am speaking from experience as a radio control scale and sport pilot, and from far too many years on flight sims. I am sorry to take your plan to bits like that, but, in truth, it has a number of issues that would affect its ability to fly in a manner you intended. I hope this frank and blunt critique helps. I wish you all the luck in the world.

[James Kerman]

I agree with the posts above.  In the VAB you have 3 tabs in the bottom left.  One is the center of lift, one is the center of thrust and the other is the center of mass.  When designing aircraft you want to have the center of lift slightly behind your center of mass. 

I would try moving the wings to the engine clusters and removing the last fuel tank.  I would also exchange the control surfaces on the wings for ailerons and add canards instead of a traditional tailplane - this should give you much more control authority. 

In the VAB you can also specify what each control surface does.  I usually set ailerons and canards to pitch and roll and tail to yaw only.  This makes the plane control much easier if you are using a keyboard.

Another thing most aircraft have is a slight angle of incidence in the wings.

Edited May 11, 2016 by James Kerman

[bewing]

Part of your problem may also be that you are trying to lift a bazillion tons of fuel. The junos are pretty efficient -- you only need one of the big tanks of fuel, at most (half full, even).

Trying to lift that much weight exacerbates all the other issues. But yeah, the way you have those Delta Deluxe winglets mounted is also very bad.

I'll say that it's usually easiest to start with a design that works and then modify it one step at a time to be what you want. Here's a simple juno-based plane that works: (you can replace the girders with a couple SciJrs, or an empty fuel tank for your first modification)

[randomredneck]

I will take all your advice under consideration, and possibly return with the results. Much appreciated.

[randomredneck]

Well, I took all the said advice...and my plane still sucks. I give up. Spaceplanes are stupid, anyway.

 

Thanks for the advice anyway.

Edited May 13, 2016 by randomredneck

[Vanamonde]

I have built lots and lots of sucky planes. The trick is not to give up and gradually figure out what works. Some of them will still suck, though. Just discard those and try again.