The Nelson H-44 is an American single ignition, four-cylinder, horizontally opposed, direct drive, two-stroke aircraft engine that was developed by the Nelson Engine Company for use in motorgliders. Design and development The H-44 was designed in the period following the Second World War and a specially designed motor glider was created by Hawley Bowlus to utilize the engine, the Bowlus/Nelson Dragonfly. The engine was not certified. Under the CAR 5 regulations then in place in the US for gliders, a certified auxiliary power glider could be flown with a non-certified engine and propeller. The engine is instead described on the Dragonfly type certificate. The four-cylinder engine runs on a 12:1 mixture of 80 octane gasoline and SAE 30 oil. It is equipped with a single Carter WA1 carburetor and a recoil starter. Operational history Employed in the Dragonfly the H-44 proved underpowered, which led to the design of the H-49 version. The engine family was not a success and few were produced. Variants H-44 Original design with a bore and stroke, producing at 3900 rpm. H-49 Upgraded design with E-225 cylinders giving a bore and stroke, producing at 4000 rpm. Applications Bowlus/Nelson Dragonfly Specifications (H-44) See also References Air-cooled aircraft piston engines Nelson aircraft engines Two-stroke aircraft piston engines