The SNECMA-Régnier 4L is a French four cylinder air-cooled inverted inline

piston engine A reciprocating engine, more often known as a piston engine, is a heat engine that uses one or more Reciprocating motion, reciprocating pistons to convert high temperature and high pressure into a Circular motion, rotating motion. This article ...

, introduced shortly after the end of

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

Design and development

Régnier Motor Company's introduction to aircraft engine production came after acquisition of licences to build the de Havilland Gipsy Major and Gipsy Six. Though they remained influenced by de Havilland practice their products began to diverge and eventually contained original designs. By the mid-1930s they had several four cylinder air-cooled inverted inline engines on offer, including the R.4L-02 displayed at the 1936 Paris Air Show. Though it shared a name with a post-war model, the two engines were very different: the 1936 engine produced from about 4 litres and with a

dry weight Vehicle weight is a measurement of wheeled motor vehicles; either an actual measured weight of the vehicle under defined conditions or a gross weight rating for its weight carrying capacity. Curb or kerb weight Curb weight (American English) or k ...

near , the later reached from 6.3 litres at a weight of . During the

Occupation of France The Military Administration in France (; ) was an Military Administration (Nazi Germany), interim occupation authority established by Nazi Germany during World War II to administer the occupied zone in areas of northern and western French Third ...

and in the years shortly after

, Régnier designed and produced a set of three simplified four-cylinder inverted air-cooled inline engines of increasing capacity and power, the 4J, 4K and 4L. The specifications of the post-war 4L engine are similar, though not identical to, those of the pre-war R.4, whilst those of the pre-war R.4L specifications are closer to that of the post-war 4K. In 1946 or 1947, Régnier, now nationalised, was absorbed into

SNECMA Safran Aircraft Engines, previously Snecma (''Société nationale d'études et de construction de moteurs d'aviation'') or Snecma Moteurs, is a French aerospace engine manufacturer headquartered in Courcouronnes and a subsidiary of Safran. It d ...

and the 4L engines, the most widely used member of the series, became the SNECMA-Régnier 4L. Notable constructional features, shared with the 4J and 4K engines, included machined steel cylinder barrels with external baked-on anti-corrosion varnish and separate

cylinder head In a piston engine, the cylinder head sits above the cylinders, forming the roof of the combustion chamber. In sidevalve engines the head is a simple plate of metal containing the spark plugs and possibly heat dissipation fins. In more modern ...

s with unusual metallo-plastic seals, held to the

crankcase A crankcase is the housing in a reciprocating engine, piston engine that surrounds the crankshaft. In most modern engines, the crankcase is integrated into the engine block. Two-stroke engines typically use a crankcase-compression design, res ...

by long bolts. Screwed-in plug bushes and valve seats were made from aluminium-bronze. The 4L's five-bearing steel

crankshaft A crankshaft is a mechanical component used in a reciprocating engine, piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating Shaft (mechanical engineering), shaft containing one or more crankpins, ...

was forged, as were the

duralumin Duralumin (also called duraluminum, duraluminium, duralum, dural(l)ium, or dural) is a trade name for one of the earliest types of age hardening, age-hardenable aluminium–copper alloys. The term is a combination of ''Düren'' and ''aluminium'' ...

connecting rod A connecting rod, also called a 'con rod', is the part of a reciprocating engine, piston engine which connects the piston to the crankshaft. Together with the crank (mechanism), crank, the connecting rod converts the reciprocating motion of the p ...

s which had split, steel backed, bronze bearings. The crankcase was cast from aluminium alloy. SNECMA continued to produce the 4L series until at least 1956. The most prolific type to use it was the military Nord NC.856A, with 112 examples.

Variants

''Data from ''Jane's All the World's Aircraft 1956/57. The types are alternatively written as 4LO-4, etc. ;4LO:early post-war designation ;4L-00: First post-war version, maximum continuous power at 2,280 rpm. ;4L-02: Higher compression ratio of 7.25:1, maximum take-off and continuous power at 2,500 rpm. ;4L-04: As 4L.00 but rearranged accessories. ;4L-06: As 4L.02 but rearranged accessories. ;4L-08: As 4L.04 but with higher compression ratio of 6.8:1, maximum take-off and continuous power . ;4L-14: ;4L-20: -00 for inverted flight ;4L-22: -02 for inverted flight ;4L-24: -04 for inverted flight ;4L-26: -06 for inverted flight ;4L-28: -08 for inverted flight ;4L-34: -14 for inverted flight

Applications

''Data from:'' Gaillard (1990)

Specifications (Régnier 4L.00 )

References

{{DEFAULTSORT:SNECMA Regnier 4L Air-cooled aircraft piston engines Inverted aircraft piston engines 1940s aircraft piston engines Snecma aircraft engines

Design and development

Variants

Applications

Specifications (Régnier 4L.00 )

See also

References