SNECMA 14R

SNECMA 14R
Type	14 cylinder two-row air-cooled radial piston engine
National origin	France
Manufacturer	Gnome-Rhône / SNECMA
Major applications	Breguet Br 500 Colmar
Developed from	Gnome-Rhône 14N

The SNECMA 14R was a 14-cylinder two-row air-cooled radial engine developed in France just prior to the start of World War II from the Gnome-Rhône 14N. The 14N radial engine was itself an improved version of the popular pre-war Gnome-Rhône 14K Mistral Major series; designed and manufactured by Gnome et Rhône, a major French aircraft engine manufacturer whose origins pre-date the First World War.

The improved 14R was initially known as the Gnome-Rhône 14P and then the Gnome-Rhône 14R. There were several improvements such as the introduction of a longer crankshaft and crankcase with a centre bearing, an increase in cylinder capacity, and a two-speed compressor. These changes allowed the engine to deliver 1,400hp at take-off and 1,300hp at 1,500m (1st gear) and 1200hp at 4000m (2nd gear). This came at the cost of a much increased total weight. It was expected that further development, such as the introduction of higher grade fuels, would lead to a power output of 1,660hp at low altitude.

With the Fall of France, engine development was stopped under the occupation. After the war, development recommenced; however production of this engine after 1945 was transferred to the newly formed SNECMA and the engine was renamed the SNECMA 14R.

Variants[edit]

14R-04: Improved higher performance using 92 Octane fuel. 14N with 2-speed supercharge (6.5:1 and 9:1), LH rotation, 1,190 kW (1,590 hp) for take-off.
14R-05: RH rotation version of 14R-4.
14R-08: RPM increased from 2,400 to 2,600 improving power output. LH rotation.
14R-09: RH rotation version of 14R-08
14R-24: LH rotation, 1,200 kW (1,600 hp).
14R-25: RH rotation version of 14R-24.
14R-26: LH rotation, 1,200 kW (1,600 hp).
14R-27: RH rotation version of 14R-26.
14R-28: LH rotation, 1,200 kW (1,600 hp).
14R-29: RH rotation version of 14R-28.
14R-32: LH rotation
14R-100
14R-200: LH rotation
14R-201: RH rotation
14R-210
28T-1: 28 cylinder, double 14R-24 engines placed back-to-back with co-axial contra-rotating propeller shafts, direct fuel injection, 2-speed supercharger, 77.4 L (4,720 cu in) displacement, delivering 2,400 kW (3,200 hp) for take-off using 100/130 octane fuel.^[1]

Specifications (14R-04)[edit]

Data from ^[2]

General characteristics

Type: 14 cylinder two-row air-cooled radial piston engine
Bore: 146 mm (5.75 in)
Stroke: 165 mm (6.50 in)
Displacement: 38.7 L (2,361.62 cu in)
Length: 1,635 mm (64.37 in)
Diameter: 1,297 mm (51.06 in)
Dry weight: 819 kg (1,805.59 lb)
Frontal Area: 1.33 m² (14.3 sq ft)

Components

Valvetrain: Single inlet and exhaust valves operated by rockers and pushrods
Supercharger: Gear-driven 2-speed supercharger at 6.5:1 and 9.0:1 ratios
Fuel system: 1x Bronzavia updraught carburettor with automatic boost and altitude control
Fuel type: 92 Octane gasoline
Oil system: Pressure fed at 480 kPa (70 psi)
Cooling system: Air-cooled with baffles
Reduction gear: Planetary / epicyclic bevel reduction gearing at 0.67:1 ratio
Starter: Air equipment electric inertia starter
Ignition: 2 x R.B. magnetos, 2 x 18 mm (0.71 in) short reach spark plugs per cylinder fed by a shielded ignition harness.

Performance

Power output:
Take-off:1,590 hp (1,185.66 kW) at 2,600 rpm at 1,180 mm (46.46 in) Hg boost with 100 octane fuel
- Military, low:1,660 hp (1,237.86 kW) at 2,600 rpm at 1,000 m (3,280.84 ft)
- Military, high:1,580 hp (1,178.21 kW) at 2,600 rpm at 5,500 m (18,044.62 ft)
- Normal, low:1,320 hp (984.32 kW) at 2,400 rpm at 2,100 m (6,889.76 ft)
- Normal, high:1,230 hp (917.21 kW) at 2,400 rpm at 6,000 m (19,685.04 ft)
Specific power: 31.85 kW/L (0.7 hp/cu.in)
Compression ratio: 6.8:1
Specific fuel consumption: 0.292 kg/kW/hr (0.48 lb/hp/hr)
Oil consumption: 0.0067 kg/kW/hr (0.011 lb/hp/hr)
Power-to-weight ratio: 1.494 kW/kg (0.909• hp/lb)
B.M.E.P.: 1,470 kPa (213 psi)
14R-05 propeller rotates in opposite direction

References[edit]

^ Wilkinson, Paul H. (1946). Aircraft engines of the World 1946 (4th ed.). London: Sir Isaac Pitman & Sons Ltd.
^ Wilkinson, Paul H. (1945). Aircraft engines of the World 1945 (3rd ed.). London: Sir Isaac Pitman & Sons Ltd.

[Wilkinson46-1] Wilkinson, Paul H. (1946). Aircraft engines of the World 1946 (4th ed.). London: Sir Isaac Pitman & Sons Ltd.

[Wilkinson-2] Wilkinson, Paul H. (1945). Aircraft engines of the World 1945 (3rd ed.). London: Sir Isaac Pitman & Sons Ltd.

[1]

[2]

v t e Gnome-Rhône aircraft engines
Gnome rotary engines	1906 25hp rotary 1907 50hp rotary 34hp 5-cyl rotary 60hp 7-cyl rotary 123hp 14-cyl rotary Delta Delta-Delta Gamma Gamma-Gamma Monosoupape 7 Type A Monosoupape 9 Type B-2 Monosoupape 9 Type N Omega Omega-Omega Lambda Lambda-Lambda Sigma
Le Rhône rotary engines	7 7A 7B 7B2 9C 9J 9R 9Z 11F 14D 18E 1912 18E 1917 28E K L M P R
Gnome et Rhône radial engines	5B 5K 7K 9A 9K 14K 14M 14N 14P 14R 18L 18R