Curtiss H-1640
The Curtiss H-1640 Chieftain (also Curtiss R-1640 ) from the American manufacturer Curtiss is an air-cooled four-stroke 2-in-line 6-radial engine (also known as a hexagon arrangement) with 12 cylinders. The cylinder banks are arranged at an angle of 60 °, the crankshaft is cranked twice and mounted in roller bearings. The propeller was driven directly.
With the development of the Townendring, radial engines lost their aerodynamic disadvantage compared to the in-line engine. The engine was tested from 1927. The arrangement of two cylinders in a row made it possible to keep the diameter of the engine smaller than that of a conventional radial engine.
The H-1640 was the first airworthy in-line radial engine of this configuration and was tested in a number of aircraft, for example in the Thomas Morse XP-13 and the Curtiss XO-18 , with support from the US authorities . Although approval for civil aviation with a take-off power of 600 hp was achieved, the cooling problems of the rear cylinder in each case could not be resolved and the project was discontinued without series production.
A similar engine is the Bristol Hydra . However, it has two 8-cylinder stars - a total of 16 cylinders, which is why it is known as an octagon engine. Its two stars are also arranged linearly (in a row) one behind the other, which also distinguishes it as a series radial engine. Other examples of hexagon motors are very rare. They include the German Junkers Jumo 222 with 24 cylinders and the Soviet, also 24-cylinder Dobrynin VD-4K .
Technical specifications
- Type: air-cooled 12-cylinder in-line radial engine with two 6-cylinder stars in a row
- Power: 615 hp at 2200 rpm
- Cylinder: 12
- Motor diameter: 1143 mm
- Bore: 142.8 mm
- Stroke: 139.7 mm
- Displacement: 26.87 l
- Ignition: Splitdorf magnet
- Carburetor: Stromberg NA-U8j
- Specific consumption: 326 g / kWh
- Weight: 408 kg