Lorraine Pétrel
| Industry | Aero engine manufacturing |
|---|---|
| Founded | before 1932 |
| Fate | Nationalised in 1937 |
| Successor | Société Nationale de Construction de Moteurs |
| Headquarters | France |
The Lorraine 12H Pétrel was a French-designed V-12 piston aeroengine featuring supercharging and gearing, originally delivering 370 kW (500 hp) and later improved to reach 640 kW (860 hp). It powered several primarily French aircraft during the mid-1930s, with some models serving experimental roles.
Design and development
During the 1930s, Société Lorraine, which became nationalised in 1937 as Société Nationale de Construction de Moteurs, continued manufacturing large water-cooled aero engines named after birds such as Eider, Courlis, Pétrel, and Sterna. By 1938, production of the latter two models was still ongoing.
The Pétrel featured an upright V-12 configuration with two banks of six cylinders set at a 60° angle, all driving a shared crankshaft. Its cylinder assemblies were attached to a split light alloy crankcase housing seven bearings for the crankshaft. Roller bearings supported the crankshaft at its ends, while plain bearings were used elsewhere. Integrated water passages within the upper crankcase ensured effective cooling.
Each cylinder included steel liners screwed into the heads that extended into the crankcase. The pistons, forged from alugir, were equipped with three compression rings and one scraper ring. These connected to six crankpins via master and auxiliary connecting rods; master rods had forked big ends fitted with white metal bearings, whereas auxiliary rods utilized bronze bushings.
Four overhead valves per cylinder (two intake and two exhaust) were actuated by overhead camshafts through T-shaped tappets designed to minimize valve stem stress. Ignition was secured by dual magnetos and two spark plugs per cylinder. A carburettor supplied the fuel-air mixture to a supercharger mounted at the rear of the engine. The output shaft could be configured for either left or right rotation thanks to a patented Lorraine epicyclic gear system employing six satellite gears, providing an 11:17 reduction ratio for propeller speed.
Lubrication was maintained by pressurized oil delivered through the crankshaft with scavenging from the sump; the supercharger had its own dedicated lubrication circuit.
First tested in 1932 producing 370 kW (500 hp), by 1938 the Pétrel had advanced into the 12Hars variant capable of producing 640 kW (860 hp). This version powered the Koolhoven F.K.55 fighter, which used counter-rotating twin-blade propellers.
Operational history
Similar to the Koolhoven F.K.55, many aircraft fitted with the Pétrel engine were unique prototypes aimed at demonstrating Lorraine’s capabilities compared to established manufacturers like Hispano-Suiza and Rolls-Royce. Nonetheless, the Potez 542 variant of the Potez 540 series was produced in significant numbers, with 74 twin-engine multi-role aircraft—serving as bombers, reconnaissance planes, and transports—delivered to French and Spanish air forces.
Variants
- 12H Pétrel
- Initial power output .
- 12Ha
- 12Hars
- .
- 12Hdr
- Developing at 2300 rpm
- 12Hdrs
- Generating at 2300 rpm
- 12Hfrs Normale
- .
- 12Hfrs Chasse
- Engineered for fighter use with increased power— at 2,800 rpm and .
- 12Hgrs
- Rated at 2800 rpm
Applications
- Breguet Br.19.10
- Fokker D.XVII
- Hawker Fury
- Hawker Hart
- Koolhoven F.K.55
- Nieuport-Delage NiD 82
- Potez 39
- Potez 542
- P.Z.L. P.8/II
- Renard R-31
- Société Aérienne Bordelaise AB-21
- French Motor Torpedo Boat Prototype 40K
Engines on display
- An example of the Pétrel engine can be found on exhibit within the aviation collection at the Musée Royal de l'Armée in Brussels.