Tesla received U.S. Patent 1,655,114, for a biplane capable of taking off vertically (VTOL aircraft)

In 1928, Tesla received U.S. Patent 1,655,114, for a biplane capable of taking off vertically (VTOL aircraft) and then of being "gradually tilted through manipulation of the elevator devices" in flight until it was flying like a conventional plane. Tesla thought the plane would sell for less than $1,000, although the aircraft has been described as impractical, although it has early resemblances to the V-22 Osprey used by the US military. This was his last patent and at this time Tesla closed his last office at 350 Madison Ave., which he had moved into two years earlier.