The Hirth HM 500 was a German four-cylinder

air-cooled Air-cooled engines rely on the circulation of air directly over heat dissipation fins or hot areas of the engine to cool them in order to keep the engine within operating temperatures. In all combustion engines, a great percentage of the heat ge ...

inverted inline engine developed from the

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 ...

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 for simplified manufacture. 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.Flugmotor Hirth HM 500, Luftfahrt International Nr 6, Dec. 1974 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 Hirth Engines GmbH is an engine manufacturer based in Benningen, Germany. It is currently a part of the UMS Aero Group. Hirth began manufacturing aero engines in the 1920s, was taken over by Heinkel in WWII to develop the Heinkel-Hirth jet en ...

engines so popular in the 1930s. Due to low fuel consumption and excellent reliability, the HM 500 was chosen as the

powerplant Propulsion is the generation of force by any combination of pushing or pulling to modify the translational motion of an object, which is typically a rigid body (or an articulated rigid body) but may also concern a fluid. The term is derived from ...

for the Bücker Bü 181.

Applications

* Bücker Bü 181

Specifications (HM 500A)

References

Notes

Bibliography

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

External links