Hirth HM 501

HM 501
Type	Inline piston engine
National origin	Germany
Manufacturer	Hirth Motoren GmbH
Major applications	Arado Ar 231
Developed from	Hirth HM 500

The Hirth HM 501 was a 6-cylinder air-cooled inverted in-line engine that was developed by Hirth Motoren GmbH in the late 1930s, from the 4-cylinder HM 500 and used principally on the submarine-born Arado Ar 231.

Applications

• Arado Ar 231

Specifications (HM 501A)

Data from Flugzeug-Typenbuch. Handbuch der deutschen Luftfahrt- und Zubehör-Industrie 1944

General characteristics

• Type: 6-cylinder air-cooled inverted in-line aircraft piston engine
• Bore: 105 mm (4.13 in)
• Stroke: 115 mm (4.53 in)
• Displacement: 5.97 L (364.3 cu in)
• Length: 1,272 millimetres (50.1 in)
• Width: 485 mm (19.1 in)
• Height: 662 mm (26.1 in)
• Dry weight: 148 kg (326 lb) dry, unequipped

155 kg (342 lb) wet, equipped

Components

• Valvetrain: one intake and one exhaust under-head valve per cylinder actuated pushrods and rockers
• Fuel system: SUM 698/2 carburetor
• Fuel type: 80 octane gasoline
• Oil system: Dry sump with one pressure and two scavenge pumps
• Cooling system: Liquid-cooled, ethylene glycol

Performance

• Power output:
  

• 160 PS (158 hp; 118 kW) at 2,550 rpm for takeoff
• 145 PS (143 hp; 107 kW) at 2,470 rpm (high performance) at sea level
• 130 PS (128 hp; 96 kW) at 2,380 rpm (max. continuous ) at sea level

• Specific power: 26.8 PS/L (0.43 hp/cu in; 19.71 kW/L)
• Compression ratio: 6.2:1
• Specific fuel consumption: 0.220 kg/PSh (0.492 lb/(hp⋅h); 0.299 kg/kWh) at max continuous
• Oil consumption: 0.002–0.003 kg/PSh (0.004–0.007 lb/(hp⋅h); 0.003–0.004 kg/kWh) at max continuous
• Power-to-weight ratio: 1.075 PS/kg (0.481 hp/lb; 0.791 kW/kg)
• B.M.E.P.: 9.46 atm (9.59 bar; 139.0 psi)

Further reading

• Nowarra, Heinz J. (1993). Die Deutsche Luftrüstung 1933-1945 Vola.4 - Flugzeugtypen MIAG-Zeppelin (in German). Koblenz: Bernard & Graefe Verlag. p. 101, 108-109. ISBN 3-7637-5468-7.