Hirth HM 504

The Hirth HM 504 is a four-cylinder air-cooled inverted inline engine. The HM 504 was a popular engine for light aircraft of the 1930s-1940s, and it was used to power a number of Germany's trainer aircraft of World War II. The engine featured a cast magnesium alloy crankcase made of Elektron^[1][2] The Hitachi Hatsukaze Model 11 was a Japanese licensed version.

Hirth HM 504
Hirth HM 504 on display at the Flugausstellung Hermeskeil
Type	Inline piston engine
National origin	Germany
Manufacturer	Hirth-Motoren GmbH, Stuttgart-Zuffenhausen
Major applications	Bücker Bü 131
Developed into	Hitachi Hatsukaze

Applications

• Arado Ar 79
• Bücker Bü 131
• Bücker Bü 181
• BŻ-1 GIL (helicopter)
• Klemm Kl 35
• Matra-Cantinieau MC-101 (helicopter)
• Morane-Saulnier MS.603
• Payen Arbalète
• Repülőgépgyár Levente II

Specifications (HM 504 A-2)

Data from Flugzeug-Typenbuch. Handbuch der deutschen Luftfahrt- und Zubehör-Industrie 1944,^[3] Der Flugmotor. Bauteile und Baumuster^[4]

General characteristics

• Type: 4-cylinder air-cooled inverted inline
• Bore: 105 mm (4.13 in)
• Stroke: 115 mm (4.53 in)
• Displacement: 3.980 L (242.87 cu in)
• Length: 945 mm (37.2 in)
• Width: 520 mm (20.5 in)
• Height: 780 mm (30.7 in)
• Dry weight: 107 kg (236 lb) dry, unequipped

124 kg (273 lb) wet, equipped

Components

• Valvetrain: 1 inlet and 1 exhaust under-valve per cylinder driven by pushrods and rockers
• Fuel type: 80 Octane
• Oil system: dry sump, pressure feed with scavenge
• Cooling system: air-cooled

Performance

• Power output:
  

• 105 PS (104 hp; 77 kW) at 2,530 rpm (5 minutes) at sea level
• 95 PS (94 hp; 70 kW) at 2,450 rpm (30 minutes) at sea level
• 85 PS (84 hp; 63 kW) at 2,360 rpm (max. continuous / cruise) at sea level

• Specific power: 26.35 PS/L (0.43 hp/cu in; 19.38 kW/L)
• Compression ratio: 6.2:1
• Specific fuel consumption: 0.228 kg/PSh (0.510 lb/(hp⋅h); 0.310 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: 0.98 PS/kg (0.44 hp/lb; 0.72 kW/kg)
• B.M.E.P.: 9.37 atm (9.49 bar; 137.7 psi)

See also

Related development

• Hitachi Hatsukaze
• Ishikawajima Tsu-11

Comparable engines

• Alfa Romeo 110
• Argus As 8
• Blackburn Cirrus Minor
• de Havilland Gipsy Minor
• Elizalde Tigre IV
• Menasco Pirate

Related lists

• List of aircraft engines