Hirth HM 500

HM 500
	Hirth HM 500
Type	Inline piston engine
National origin	Germany
Manufacturer	Hirth
First run	1938
Major applications	Bücker Bü 181
Developed from	Hirth HM 504

The Hirth HM 500 was a German four-cylinder air-cooled inverted inline engine developed from the Hirth HM 504 in 1938. Although developing the same output of the HM 504 (105 hp) and keeping the same capacity and bore, the HM 500 was a very different engine; the new HM 500 had a one-piece "closed" crankcase^[1] for simplified manufacture.^[2] The new cooling system reduced cylinder temperatures considerably (15 °C less), and the fuel consumption was also reduced. The HM 500 carried a twin-magneto instead of the two separate magnetos as on the old HM 504. All these changes made that the HM 500 resulted a 12% lighter than the HM 504 and the front surface 37% less than the previous HM 504.^[3]

Otherwise the HM 500 continued the typical Hirth use of built-up crankshafts and roller-bearings for crankshaft & connecting rods (Hirth patents) as well as magnesium-alloy crankcases which made Hirth engines so popular in the 1930s.

Due to low fuel consumption and excellent reliability, the HM 500 was chosen as the powerplant for the Bücker Bü 181.

Applications

Bücker Bü 181

Specifications (HM 500A)

General characteristics

Type: 4-cylinder air-cooled inverted inline
Bore: 105 mm (4.134 in.)
Stroke: 115 mm (4.528 in.)
Displacement: 3983 cm³ (243.1 cuin)
Length: 978 mm
Width: 420 mm
Height: 665 mm
Dry weight: 91.50 kg (core)

Components

Valvetrain: 1 inlet and 1 exhaust valve per cylinder
Fuel type: A3 (80 octane)
Cooling system: air

Performance

Power output: 105 hp at 2500 RPM
Compression ratio: 6:1
Fuel consumption: 210 -230 gr /PSh
Oil consumption: 3g /PSh

References

Notes

^ The HM 504 had a three part crankcase
^ The time consumed to build an engine passed from an average 1775 minutes on the HM 504 to 945 minutes with the new HM 500
^ Flugmotor Hirth HM 500, Luftfahrt International Nr 6, Dec. 1974

Bibliography

Der Hirth Flugmotor HM 500, 1944
Die Entwicklung der Hirth-Motoren, 1942

External links

Göbler-Hirthmotoren Company website

[1] The HM 504 had a three part crankcase

[2] The time consumed to build an engine passed from an average 1775 minutes on the HM 504 to 945 minutes with the new HM 500

[3] Flugmotor Hirth HM 500, Luftfahrt International Nr 6, Dec. 1974

[1]

[2]

[3]