Helicopter Aeroplane 1920 = OB; v: 150. Had ordinary tractor prop, plus a horizontal prop in a cut-out of the upper wing, which would allow near-vertical descent. Claimed climb to 18,000' in 10 minutes.
Helicopter Aeroplane c.1932 = OhwM. A realization of the 1920 design, possibly a rebuilt Crawford A-1 Parasol, since its registration [X12205] earlier belonged to such a machine. The horizontal prop was driven by a separate engine, mounted in the wing. The added weight of this engine made the airplane too heavy, and cooling was blocked by the fuselage—it probably never flew.