Here are pictures and descriptions of planes that didn't fly very well. Failures are very instructive, if you get to know why they failed. Unfortunately, most people don't talk about their failures.
This plane is designed to take off vertically. Unlike the original A.D.V.E.R.S.E., the motor is in a central position. This avoid hurting the motor or the prop in case of a nose crash.
The plane is powered by a GWS LPS CN12-RLC 4.8V B (5:1 gear ratio) with a 8043 GWS prop and a 2 cell 880mAh Kokam LiPo battery. The plane does take off vertically, but it is practically uncontrollable. I am guessing that the left wing is always stalled because of the prop wash.
This is a pseudo X-Wing fighter inspired by Star Wars. It is powered by a GWS EDF-50 and a 2 cell 880mAh Kokam LiPo battery. The plane was too small and too heavy.
An auto-gyro built by Kevin, Yann and Jean-Claude LeCun. It had all the right things for it to fly succesfully, but it obstinately insisted on rolling left and flipping upside down. This behavior was undoubtedly caused by the prop torque.
The idea was to use the wings as control surfaces (a bit like elevons). This was a complete failure. The wings were made of a flat 6mm Depron sheet. This gave them a very flat airfoil that stalls at very small angle of attacks. A tiny upward deflection on a wing would immediately cause the angle of attack to go above the stall. The glider would snap into a spin.