| R-540 Whirlwind | |
|---|---|
 Wright R-540 Whirlwind installed in aTravel Air 16E at theHistoric Aircraft Restoration Museum | |
| Type | Air-cooled 5-cylinderradial piston engine |
| National origin | United States |
| Manufacturer | Wright Aeronautical Corporation |
| Major applications | Various light aircraft |
| Manufactured | 1929-1937 |
| Number built | around 500 |
TheWright R-540 Whirlwind was a series of five-cylinder air-cooledradialaircraft engines built by theWright Aeronautical division ofCurtiss-Wright. These engines had adisplacement of 540 in³ (8.85 L) and power ratings of around 165-175 hp (123-130 kW). They were the smallest members of theWright Whirlwind engine family.
Wright introduced the J-6 Whirlwind family in 1928 to replace the nine-cylinderR-790 series. The J-6 family included varieties with five, seven, and nine cylinders. The five-cylinder version was originally known as theJ-6 Whirlwind Five, orJ-6-5 for short. The U.S. government designated it as theR-540; Wright later adopted this and dropped the J-6 nomenclature.
Like all the members of the J-6 Whirlwind family, the R-540 had larger cylinders than the R-790. The pistonstroke of 5.5 in (14.0 cm) was unchanged, but the cylinderbore was expanded to 5.0 in (12.7 cm) from the R-790's bore of 4.5 in (11.4 cm). While the R-790 wasnaturally aspirated, the R-540, like the other J-6 engines, had a gear-drivensupercharger to boost its power output.
Wright gradually refined the R-540, using suffix letters to indicate successive versions. For example, the R-540A had 165 hp (123 kW), while the R-540E of 1931 had power boosted to 175 hp (130 kW) thanks to an improvedcylinder head design. Wright sometimes named these versions according to their power, e.g. "Whirlwind 165" or "Whirlwind 175".[1]
The engine was built inSpain as theHispano-Suiza 5Q orHispano-Wright 5Q without modification apart from the use of Hispano's patented nitriding finishing process.[2]
The R-540 was the smallest, least powerful member of the Whirlwind family and was designed for light aircraft. One of the more popular types to use it was theCurtiss Robin, a light civil utility aircraft. A few were also used in prototype military trainer aircraft that were evaluated by the U.S. Army but not put into production.
The R-540 sold well at first, with over 400 engines being built in 1929.[3] However, with the impact of theGreat Depression, sales plummeted, and only about 100 further examples were built over the next eight years.[3] Wright finally ceased production of five-cylinder Whirlwinds in 1937,[3] concentrating on larger engines and leaving the market for small radials to companies likeKinner andWarner.
Since R-540 engines were found solely in light aircraft, they weren't often used for groundbreaking flights. However, there were a couple of noteworthy exceptions which took advantage of the Whirlwind family's reputation for high reliability. In 1935, the brothersAl and Fred Key set a new flight endurance record of 653 hours, 34 minutes in the Curtiss Robin J-1Ole Miss, flying overMeridian, Mississippi, from June 4 to July 1. Their plane was refueled and resupplied in flight, and they could perform simple engine maintenance by walking out on a small catwalk extending between the cabin and the engine.Douglas "Wrong-Way" Corrigan's famous unauthorized transatlantic flight fromNew York City toDublin,Ireland on July 17–18, 1938, used a Curtiss Robin with an R-540 built from the parts of two used engines.[4]
Wright R-540 engines on display are uncommon, but there is one at theStrategic Air and Space Museum (formerly the Strategic Air Command Museum) nearAshland, Nebraska.[5] Another is on display at the Shannon Air Museum inFredericksburg, Virginia.
Data fromFAAtype certificate data sheet for the R-540E;[6] dimensions from Curtiss-Wright (1983).
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