US Patent 9975631 Tiltwing multicopter with foldable and non-foldable propellers

An aircraft includes a front tiltwing which in turn includes two non-foldable outer propellers and four foldable inner propellers. The four foldable inner propellers are rotating at least some of the time while the front tiltwing is held in a vertical takeoff and landing position. The four foldable inner propellers are stowed at least some of the time while the front tiltwing is held in a forward flight position. The aircraft also includes a back tiltwing which includes two non-foldable back propellers.