Tumansky M-87
# Tumansky M-87

The Tumansky M-87 was a Soviet air-cooled aircraft radial engine that was developed in the late 1930s. It was a development of their licensed Gnome-Rhone 14K engines that started with the M-85.

## Development

In 1934, USSR licensed the French Gnome-Rhone 14K aircraft engine producing 800 hp (595 kW), which entered production as the M-85. The engine was subsequently modified to M-86 which produced 960 hp (715 kW) at takeoff thanks to increased supercharging and a higher compression ratio. The M-87 was created to further increase the power output. Cylinders and pistons were revised to increase the compression ratio and the supercharger was redesigned. The resulting engine had better high-altitude performance and entered production in 1938. However, the engine proved unreliable and suffered from failure of gears in the reduction gearbox. Later the M-88 was designed to address the shortcomings of the M-87. At first the M-88 was not a success, but the designers persisted, and the M-88 was made into a reliable and widely produced engine. The M-87 was used in Ilyushin Il-4 and Sukhoi Su-2 bombers, and the Polikarpov I-180 fighter.

## Specifications (M-87)

### General characteristics

* Type: Two-row, 14-cylinder, air-cooled supercharged radial engine
* Bore: 146 mm (5.748 in)
* Stroke: 165 mm (6.496 in)
* Displacement: 38.673 L (2,360 in³)
* Dry weight: 640 kg (1,140 lb)

### Components

* Supercharger: Centrifugal type supercharger
* Cooling system: air

### Performance

* Power output: 950 hp (710 kW) at 2,250 rpm for takeoff and at 4,500 m (14,765 ft)
* Specific power: 18.4 kW/L (0.4 hp/in³)
* Compression ratio: 6.1:1
* Power-to-weight ratio: 1.1 kW/kg (0.8 hp/lb)
