What's wrong with my plane?

[Kantall]

My plane is stable on the runway which is nice, but the oversteer is ridiculous. I tap the key and it does a flip. When taking off it's far from a gradual incline and more like a backflip too.

Everything is symmetrical of course and the engine that's obscured from view in the middle of the main shaft at the back is a weasley, with the basic engines on the four attached tanks.

http://tinypic.com/r/2h6vhiq/9

 

Edited December 5, 2015 by Kantall

[acc]

hit capslock, which enables fine control

[Hyomoto]

Are your elevators set to also affect roll?  Because those produce a heck of a lot of lateral force.  Otherwise you could try pushing your ailerons further in, it really shouldn't be necessary from what I can see but if the previous solution doesn't work it might be worth looking into.

[Kantall]

6 minutes ago, Hyomoto said:

Are your elevators set to also affect roll?  Because those produce a heck of a lot of lateral force.  Otherwise you could try pushing your ailerons further in, it really shouldn't be necessary from what I can see but if the previous solution doesn't work it might be worth looking into.

Sorry if I sound a little stupid, but by elevators does that mean the two fins at the back? Everything is set to pitch, yaw and roll. Should it not be?

[acc]

how you should setup control surfaces:

set the flaps to a actiongroup and deploy them on start and landing to increase lift

[GoSlash27]

11 minutes ago, Kantall said:

Sorry if I sound a little stupid, but by elevators does that mean the two fins at the back? Everything is set to pitch, yaw and roll. Should it not be?

Kantall,

 You'll definitely have an easier time if your elevators (the horizontal fins at the back) are set to only pitch, the ailerons (control surfaces on the wings) are set to only roll, and the rudder (single vertical fin at the back) is set to only yaw. I personally prefer to not have the rudder respond to *any* inputs.

Best,

-Slashy

[Kantall]

Thankyou very much guys, some amazing information here, going to test this all right now.

 

Thanks again!

[Vanamonde]

Key operation flips the control surfaces from zero to max, so your life will be vastly simplified if you use a joystick for KSP aircraft, since those allow partial deflection of the control surfaces. Doesn't have to be a fancy one. 

[Snark]

It's especially important to turn off roll authority for your vertical stabilizer.  Otherwise, it will be trying to help you roll the plane, which will induce yaw, and it ends up fighting itself.