http://prntscr.com/ibgmal
I think it has something to do with the wings on ground principle but I am not sure... As the speed of the plane goes up, the pitch goes up, as the speed goes down it pitches back down gaining more speed.
http://prntscr.com/ibh4gl <-- that is a building guide you can try in real life, you just need a really thin wooden plank that is 10cm thick and a long stick and some tape
http://prntscr.com/ibh5m9 here is how it would look, I made this at a university (TU delft), it has a little hook at the front to launch it using an elastic taped to the ground. sadly I didn't bother to film it, and I don't have it anymore.
here is a video of it in ksp
It flies without gimbal, control surfaces or SAS