Hirth HM 504

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

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.

Applications

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)

References

^ Gunston, Bill (1989). World Encyclopaedia of Aero Engines (2nd ed.). Cambridge, England: Patrick Stephens Limited. p. 77. ISBN 978-1-85260-163-8.
^ "Werkstoff-Volumenanteile der 'AR' 79" [Materials proportions by volume of the AR 79 (advertising back matter) ]. Flugsport (in German). 31 (8). Frankfurt/Main: 229 [pdf 32]. 12 April 1939.
^ Schneider, Helmut (Dipl.Ing.) (1944). Flugzeug-Typenbuch. Handbuch der deutschen Luftfahrt- und Zubehör-Industrie 1944 (in German) (Facsimile reprint 1986 ed.). Leipzig: Herm. Beyer Verlag. p. 396. ISBN 381120484X.
^ Katz, Hans (Dr.Ing) (1940). Der Flugmotor. Bauteile und Baumuster. Luftfahrt Lehrbücherei Band 7. Berlin: de Gruyter.

External links

Göbler-Hirthmotoren Company website (nothing in there about pre-war engines)

[Gunston-1] Gunston, Bill (1989). World Encyclopaedia of Aero Engines (2nd ed.). Cambridge, England: Patrick Stephens Limited. p. 77. ISBN 978-1-85260-163-8.

[2] "Werkstoff-Volumenanteile der 'AR' 79" [Materials proportions by volume of the AR 79 (advertising back matter) ]. Flugsport (in German). 31 (8). Frankfurt/Main: 229 [pdf 32]. 12 April 1939.

[schneider-3] Schneider, Helmut (Dipl.Ing.) (1944). Flugzeug-Typenbuch. Handbuch der deutschen Luftfahrt- und Zubehör-Industrie 1944 (in German) (Facsimile reprint 1986 ed.). Leipzig: Herm. Beyer Verlag. p. 396. ISBN 381120484X.

[Katz-4] Katz, Hans (Dr.Ing) (1940). Der Flugmotor. Bauteile und Baumuster. Luftfahrt Lehrbücherei Band 7. Berlin: de Gruyter.

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