Hirth HM 504

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HM 504

The Hirth HM 504 is a German aircraft engine that was mainly used in school and sports aircraft of the 1930s.

development

The HM 504 was developed in 1934 as the successor to the HM 60 and as the first member of the 500 series, which also included the HM 506 , the HM 508 and the HM 512 , whereby the last two digits of the designation reflect the number of cylinders used . Hellmuth Hirth used a modular system of the individual components in the construction, which he had already developed for the predecessor and which he had further refined for the 500 series of motors. It was essentially based on the use of unit cylinders, each with a cubic capacity of one liter, as well as the subdivision of the crankshaft into individual sections, which were connected to one another by the so-called Hirth coupling and enabled the low-resistance use of roller bearings in the crankshaft drive .

About 6000 units of the HM 504 were built. Ringhoffer-Tatra in Kopřivnice produced it under license from 1934. Its successor was the HM 500 from 1939 with a modified crankcase .

construction

HM 504 is an air-cooled four cylinder - four cycle - queuing engine having arranged hanging cylinders , fresh oil - dry sump lubrication and oil return pump . The cylinders are made of gray cast iron with attached heads made of light metal and are connected through tie rods on the crank case of electron secured, the lid serves as an oil reservoir. Each cylinder is equipped with one inlet and one outlet valve, which is controlled by the roller-bearing camshaft via needle-bearing rocker arms, push rods and tappets . The EC pistons are made of Y light metal, the connecting rods with an H-shaped cross-section are made of chrome-nickel steel. The crankshaft with Hirth serration is split and runs on five roller bearings and one radial bearing. The ignition is carried out by a Bosch magneto with electric ignition point adjustment. Two spark plugs are provided per cylinder .

commitment

HM 504 in a class 35

Technical specifications

Parameter Data (Hirth HM 504 A 2)
Length over all 0.96 m
Width over everything 0.51 m
Height above everything 0.73 m
drilling 105 mm
Hub 115 mm
Cylinder displacement 1 l
Total displacement 3.98 l
compression 6.0
Continuous performance
on the ground
85 hp (63 kW) at 2360 rpm
Increased continuous output (30 min)
on the ground
95 hp (70 kW) at 2450 rpm
Best travel performance
on the ground
75 hp (55 kW) at 2270 rpm
Short power (5 min)
on the ground
105 PS (77 kW) at 2530 rpm
Dry weight 112 kg without equipment
Power to weight ratio 1.07 kg / hp
Displacement 26.3 hp / l
Fuel consumption
for travel services
220 g / PSh (16.5 kg / h)
Lubricant consumption
for travel service
1.5 g / PSh (0.1 kg / h)
Octane number 80

literature

  • Werner von Langsdorff : Handbook of aviation . Born in 1939. 2nd, unchanged edition. J. F. Lehmann, Munich 1937, p. 526/527 and 559 .
  • Kyrill von Gersdorff, Kurt Grasmann: aircraft engines and jet engines . In: German aviation . Bernard & Graefe, Munich 1981, ISBN 3-7637-5272-2 , pp. 127 ff .

Web links

Commons : Hirth HM 504  - Collection of images, videos and audio files

Individual evidence

  1. Vaclav Nemecek: Československá letadla. , Naše vojsko, Prague 1968, pp. 318/319