Hirth HM 512

HM 512
Type	Air-cooled inverted V-12 piston engine
National origin	Germany
Manufacturer	Hirth-Motoren G.m.b.H, Stuttgart
Designed by	Hellmuth Hirth
Number built	small numbers^[1]
Developed from	Hirth HM 506

The Hirth HM 512 was a 12-cylinder development of the earlier, 6-cylinder HM 506, produced in the late 1930s. Both were supercharged, inverted V, air-cooled engines.^[2]

Design and development

The HM 512 shared the same bore and stroke (105 mm × 115 mm) and 6:1 compression ratio with the rest of the HM500 series air-cooled engines. Other shared features were Hirth's use of roller bearings in the crankshaft and at both ends of connecting rods. The crankshaft was of typical Hirth multipart design, the 12-cylinders requiring 7 roller bearings. Like the HM 508, the drive was geared down by 1:1.5.^[3]

Variants

HM 512A: Initial version; take off power 400 hp (300 kW), continuous 360 hp (270 kW)
HM 512B: Take off power 450 hp (335 kW), continuous 360 hp (270 kW)^[3]

Applications

Dornier Do 212

Specifications (HM 512A-0)

Data from Grey 1972, p. 61

General characteristics

Type: Inverted 60° V-12-cylinder air-cooled piston
Bore: 105 mm (4.128 in)
Stroke: 115 mm (4.52 in)
Displacement: 11.94 L (728.6 cu in)
Length: 1,507 mm (59.33 in)
Width: 680 mm (26.87 in)
Height: 853 mm (33.58 in)
Dry weight: 270 kg (595 lbs)

Components

Supercharger: Light alloy centrifugal type, driven at 3.86 times crankshaft speed.
Fuel system: Supercharger drew through twin Pallas 65VH2 carburetters with automatic mixture control and equipped for inverted flight. One Bosch double magneto with automatic advance.
Oil system: Metered fresh oil to cylinder barrels and crankshaft bearings. Splash lubrication for supercharger and camshaft. Stökicht Sun and planet reduction gear lubricated by high pressure oil.
Cooling system: Air

Performance

Power output: maximum 270 kW (360 hp) at 3,000 rpm, rated 224 kw (300 hp) at 2,810 rpm, take off 300 kW (400 hp)
Compression ratio: 6.0:1

References

Notes

↑ Gunston 1989, pp. 76–7
↑ Pearce, William. "FKFS Gruppen-Flugmotor A, C, and D". oldmachinepress.com. Retrieved 8 May 2016.
1 2 Grey 1972, p. 61

Bibliography

Grey, C.G. (1972). Jane's All the World's Aircraft 1938. London: David & Charles. ISBN 0-7153-5734-4.
Gunston, Bill (1989). World Encyclopaedia of Aero Engines (2 ed.). Wellingborough: Patrick Stephens Ltd. ISBN 1-85260-163-9.

Hirth and Heinkel-Hirth aircraft engines
Piston engines	HM 8 HM 60 HM 150 HM 500 HM 501 HM 504 HM 506 HM 508 HM 512 HM 515
Two-strokes	F-23 F-30 F-33 F-36 F-263 2702 2703 2704 2706 3002 3003 3202 3203 3502 3503 3701 3702 3703
Gas turbines	HeS 1 HeS 3 HeS 8 HeS 30 HeS 40 HeS 50 HeS 60 HeS 011

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