Hirth HM 508

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The Hirth HM 508 was built in 1936/37 by Hirth Motoren GmbH in Stuttgart- Zuffenhausen . There was an air-cooled eight-cylinder - V-type engine with a 60 °  bank angle , hanging cylinders ( crankshaft above), the propeller gearbox and a mechanical loader . Ultimately, the engine did not prevail and the Argus As 10 became the standard engine in this class.


HM 508 as a cutaway model in the Aviation Museum in Krakow
HM 508A
Prototype with an output of 240 hp
HM 508C
first series version with a high-altitude loader with an 8.8-fold ratio and 270 HP take-off power. Used in the four-engine Heinkel He 116 , but also in the Bf 108 C , which surpassed the existing class altitude record of 7,985 m with 9,125 m
HM 508D
with a floor loader and a take-off power of 280 hp - e.g. T. probably in the Focke-Wulf Fw 58 used
HM 508E
with a starting power of 240 hp in the few twin-engine Gotha Go 146
HM 508H
Consumption-optimized version with 240 HP starting power, which was used in the twin-engine Siebel Fh 104 and the long-distance record machine Heinkel He 116 V3
HM 508J
Designation of a version with a controllable pitch propeller

The forerunner Hirth HM 8

A forerunner with 225 hp was used under the designation Hirth HM 8a (also 8U) on the European sightseeing flight in 1934 in addition to the 215 hp Argus AS 17A engine in eight of the 13 machines launched by the German side. Of the three  Messerschmitt Bf 108 with Hirth engine that were still started under the designation BFW M 37, Theo Osterkamp was the second-best German who came in 5th ahead of his brand companion Werner Junck . The best German was Hans Seidemann in third on a Fieseler Fi 97 with an Argus engine. All five machines of this type made it to the finish line, those with Hirth engines in positions 9, 13 and 16. However, all four Klemm Kl 36  - two of them with Hirth engines - were eliminated.

Use in Italian prototypes

An Ambrosini SAI.7 racing aircraft, powered by a Hirth HM 508D engine, set a new class world record of 100 km on a closed course at 403.9 km / h on August 27, 1939. In June 1940 the HM-508D engine was also installed in the prototypes of the Italian observation aircraft IMAM Ro.63 and AVIS C.4 . Hirth 508 also received the prototype and six series machines from the trainer Nardi FN.315 , two of which were delivered to Switzerland.

Technical specifications

Parameter HM 508C HM 508D-1 HM 508H-1
Starting power 270 hp (199 kW) at 3000 rpm 280 hp (206 kW) at 3100 rpm 240 hp (177 kW) at 3000 rpm
Climb performance 245 hp (180 kW) at 2900 rpm 255 hp (188 kW) at 2990 rpm 215 hp (158 kW) at 2900 rpm
Continuous output 215 hp (158 kW) at 2785 rpm 225 kW (306 hp) at 2875 rpm 190 kW (258 hp) at 2780 rpm
Firing order 1-6-3-5-4-7-2-8
Cylinder displacement 0.995 L.
Total displacement 7,960 L.
Hub 115 mm
drilling 105 mm
compression 6.2: 1
Loader ratio 8.8 times 4.47 times 3.86 times
Full throttle 3000 m 0 m
length 1312 mm (without hub) 1289 mm (without hub) 1290 mm (without hub)
width 683 mm 680 mm
height 827 mm 815 mm 820 mm
fuel at least 87 octane at least 80 octane
Dry matter 215 kg 208 kg 205 kg
Installation dimensions 252 kg 246 kg 230 kg


Web links

Commons : Hirth HM 508  - Collection of images, videos and audio files

Individual evidence

  1. ^ Helmut Schneider: Airplane Type Book . Handbook of the German aviation and accessories industry. Reprint of the original edition from 1939/40. Gondrom, Bindlach 1986, ISBN 3-8112-0627-3 , p. 186 .
  2. ^ Schneider, p. 188
  3. ^ Schneider, p. 189