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Wright J-6 Whirlwind Five / J-6-5 / R-540
Hispano-Suiza 5Q / Hispano-Wright 5Q

Wright R-540 Whirlwind


The Wright R-540 Whirlwind was a series of five-cylinder air-cooled radial aircraft engines built by the Wright Aeronautical division of Curtiss-Wright. These engines had a displacement of 540 (8.85 L) and power ratings of around 165-175 hp (123-130 kW). They were the smallest members of the Wright Whirlwind engine family.
Wright introduced the J-6 Whirlwind family in 1928 to replace the nine-cylinder R-790 series. The J-6 family included varieties with five, seven, and nine cylinders. The five-cylinder version was originally known as the J-6 Whirlwind Five, or J-6-5 for short. The U.S. government designated it as the R-540; Wright later adopted this and dropped the J-6 nomenclature.
The R-540 cylinders are of a steel barrel over which an aluminium alloy head is screwed and shrunk. Intake ports are at the rear with exhaust ports on the forward side of cylinder.
The crankcase assembly is composed of four major castings of aluminium alloy. The cam follower housing carrying the tappet guides is cast integral with the main section of the crankcase.
Two-piece single-throw crankshaft with one-piece master rod and “H” section articulated rods.
Aluminium alloy pistons, cross ribbed on under side of head, and fitted with full floating hollow pins held in place by expanding spring wire locks.
Tulip shaped valves, solid stem inlet valves and hollow stem exhaust valves.
Rotary induction system of Wright design, with “pre-heating” device on carburettor. Provision is made for obtaining, at all times, a clean supply of air to the carburettor.
Lubrication system is designed to eliminate all external oil pipes to the engine.
Equipment supplied was air cleaner and heater, nose cowling, complete exhaust manifold, priming pump, ignition switch, tool kit, external oil filter, and instruction book.
Accessories available at extra cost were Ecllipse hand inertia starter, Eclipse generator, Eclipse generator control box, standard steel propeller hub, fuel pump, Eclipse combination hand and electric inertia starter, Eclipse hand starter with booster magneto, Eclipse electric inertia starter, propeller hub for wooden propeller, metal propeller, and hubs for two or three blade props.
Like all the members of the J-6 Whirlwind family, the R-540 had larger cylinders than the R-790. The piston stroke of 5.5 in (14.0 cm) was unchanged, but the cylinder bore 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 was naturally aspirated, the R-540, like the other J-6 engines, had a gear-driven supercharger 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 improved cylinder head design. Wright sometimes named these versions according to their power, e.g. "Whirlwind 165" or "Whirlwind 175".
Produced from 1929 to 1937, around 500 were built.
The engine was built in Spain as the Hispano-Suiza 5Q or Hispano-Wright 5Q without modification apart from the use of Hispano's patented nitriding finishing process.
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 the Curtiss 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. However, with the impact of the Great Depression, sales plummeted, and only about 100 further examples were built over the next eight years. Wright finally ceased production of five-cylinder Whirlwinds in 1937, concentrating on larger engines and leaving the market for small radials to companies like Kinner and Warner.
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 brothers Al and Fred Key set a new flight endurance record of 653 hours, 34 minutes in the Curtiss Robin J-1 Ole Miss, flying over Meridian, 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 from New York City to Dublin, Ireland on July 17–18, 1938, used a Curtiss Robin with an R-540 built from the parts of two used engines.


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Waco BSO




Type: 5 cylinder, air cooled fixed radial
Military Rating: 165 hp at 2000 rpm
Commercial Rating: 165 hp at 2000 rpm
Displacement: 540
Compression ratio: 5.1-1
Bore: 5 in
Stroke: 5 1/2 in
Length: 40 5/8 in
Diameter: 45 in
Weight: 370 lb
Fuel consumption: not more than .55 lb/hp/hr
Oil consumption: not more than .035 lb/hp/hr
Lubrication: Pressure pumps
Ignition: Scintilla dual
Carburation: Stromberg, single barrel
Spark plugs: 2 per cylinder
Price: $3000


Type: 5-cylinder supercharged air-cooled radial piston engine
Bore: 5.0 in (127 mm)
Stroke: 5.5 in (140 mm)
Displacement: 540 cu in (8.85 L)
Length: 41.1 in (104.4 cm)
Diameter: 45.0 in (114.3 cm)
Dry weight: 420 lb (191 kg)
Valvetrain: 2 valves per cylinder, pushrod-actuated
Supercharger: gear-driven, 7.05:1 impeller gear ratio
Fuel type: 65 octane
Reduction gear: Direct drive
Power output: 175 hp (130 kW) at 2,000 RPM at sea level
Specific power: 0.324 hp/cu-in (14.7 kW/L)
Compression ratio: 5.1:1
Power-to-weight ratio: 0.417 hp/lb (0.685 kW/kg)






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