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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.[1]

Nelson H-44
Type	Two-stroke aircraft engine
National origin	United States
Manufacturer	Nelson Engine Company
Designed by	Ted Nelson
Major applications	Bowlus/Nelson Dragonfly
Produced	circa 1947

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.[1]

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.[1]

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.[1]

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.[2][3]

Variants

H-44

Original design with a 2.25 in (57 mm) bore and 2.75 in (70 mm) stroke, producing 25 hp (19 kW) at 3900 rpm.[1]

H-49

Upgraded design with E-225 cylinders giving a 2.375 in (60 mm) bore and 2.75 in (70 mm) stroke, producing 28 hp (21 kW) at 4000 rpm.[1]

Applications

• Bowlus/Nelson Dragonfly[2][3]

Specifications (H-44)

Data from FAA Type Certificate Data Sheet[1]

General characteristics

• Type: Four-cylinder, two-stroke, single-ignition aircraft engine
• Bore: 2.25 in (57 mm)
• Stroke: 2.75 in (70 mm)
• Displacement: 44 cubic inches
• Dry weight: 40 lb (18 kg)
• Designer: Ted Nelson

Components

• Fuel system: Carter WA1 carburetor
• Fuel type: 80 octane gasoline
• Oil system: premixed oil in fuel, SAE 30 oil mixed at 12:1 fuel to oil
• Cooling system: air
• Reduction gear: none

Performance

• Power output: 25 hp (19 kW) at 3900 rpm
• Compression ratio: 9:1

See also

• List of aircraft engines

References

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