Not got onto space planes much Tank. I had a dabble and they will require a little more thought. Once my station is up and running (lost the whole lot and have to rebuild it) i will try to make one up and post here.
What mods do you use on your space plane ?
Its all stock. I haven't dabbled with mods much.
I've had some pretty cool stuff but can hardly get them off the ground. I always yaw terribly on take off which roles and explodes me.
Sounds like you need to stiffen the aircraft's frame with struts. It tends to happen with my early designs, normally part of the aircraft's structure roles slightly and a wheel edges to one side or another.