Ranger XH-1850, 24 cylinder air cooled H engine. Having two crankshafts driving a hollow propeller shaft through which a cannon could be fired.

There is no evidence that it was ever used in an aircraft.

The XH-1850 had a displacement of 1849.1 in³. Output of the supercharged XH-1850 was projected to be 1,200 hp to 1,500 hp. Only eight XH-1850 engines were built, and at least one, an XH-1850-2, survives in the collection of the National Air and Space Museum. This photo was taken in 1975 at the San Diego Aviation Museum. It was most likely destroyed in the Museum fire of Feb 22, 1978.