Wright Whirlwind

The Wright Whirlwind was a family of air-cooled radial aircraft engines built by Wright Aeronautical (originally an independent company, later a division of Curtiss-Wright). The family began with 9-cylinder engines and later expanded to include 5-cylinder and 7-cylinder varieties.

History

The Whirlwind was a direct descendant of the Lawrance J-1, a 9-cylinder air-cooled radial built by the Lawrance Aero Engine Company for the U.S. Navy. The Navy was very enthusiastic about air-cooled radials and was concerned that Lawrance couldn't produce enough engines for its needs but the larger engine makers, Wright and Curtiss, had no interest in building such engines. The Navy suggested to Wright that it purchase the Lawrance company and build the J-1 itself. For added incentive, the Navy also told Wright that they would buy no more of Wright's liquid-cooled engines or spares for them. Since the Navy's purchases were a big chunk of Wright's business, Wright was thus forced to purchase Lawrance in 1923. Further J-1 engines were built by Wright.

Wright introduced the J-3 later in 1923 to fix some flaws in the J-1. (The "J-2" designation had already been used by Lawrance for an experimental design of larger bore which never went into production.) The J-4 "Whirlwind" of 1924 was the first model in the series to carry that name and the J-5 Whirlwind of 1925 (later designated the R-790 by the U.S. government) had a greatly improved cylinder design. All of these engines were 9-cylinder radials with 4.5-inch (114 mm) bore and 5.5-inch (140 mm) stroke.

In the J-6 Whirlwind series, Wright expanded the cylinder bore to 5.0 inches (127 mm). The first engine of this series, the 7-cylinder R-760, had fewer cylinders than the older Whirlwinds but was similar in displacement and power. Wright later followed it with the larger 9-cylinder R-975 and the smaller 5-cylinder R-540, providing a range of power levels while using the same basic design.

During the 1930s, Wright developed two Whirlwind versions, the R-1510 and R-1670, which used a 14-cylinder double-row configuration. However, these never got past the experimental stage and were only used in aircraft prototypes.

The Whirlwind was lighter and more reliable than a liquid-cooled engine of similar power, since the latter's cooling system added weight and required extra maintenance. Thanks to these advantages Whirlwind engines were used widely and were built in large numbers. Licensed copies were produced by manufacturers such as Continental Motors, Hispano-Suiza, and Shvetsov. The Whirlwind's success led to the development of other air-cooled radial engines throughout the 1920s, 1930s, and 1940s and these gradually eclipsed most liquid-cooled aircraft engines.

The reliability of Whirlwind engines led aviators to use them for a number of record-setting distance and endurance flights. The most famous of these is Charles Lindbergh's solo transatlantic flight in May 1927 in his single-engine Ryan monoplane, "Spirit of St. Louis". In June 1927 Albert Hegenberger and Lester Maitland made the first successful flight from the continental U.S. to Hawaii in the Fokker C-2 trimotor "Bird of Paradise", powered by three Whirlwinds. 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", powered by a Whirlwind R-540. The plane was refueled in flight and a catwalk leading to the engine allowed the pilots to perform necessary maintenance. Douglas Corrigan combined parts from two R-540s to form a useable one on his "wrong way" flight to Ireland in 1938.

During World War II Continental Motors built the R-975 under license for use in Allied tanks and other armored vehicles, thousands of which used this engine. When used in a tank, the Whirlwind had a cooling fan attached to its power shaft to provide the same cooling effect as an airplane's propeller blast. Use of the high-octane fuel in the tanks brought with it an unfortunate danger however—when idling for long periods high octane fumes gathered around the vehicle, which could be ignited and cause a flash fire [Steven Pressfield "Killing Rommel" Doubleday Publishing, 2008] .

The Whirlwind J-5 was produced under license by, among others in Poland, first by the Polish Škoda Works branch ("Polskie Zakłady Skody") in 1929-1931—about 350-400 were built—then in 1935-1938 a further 300 engines were manufactured by the Avia factory in Warsaw. They were used in numerous Polish aircraft.

Variants

There were a large number of Whirlwind versions; only a selection are listed here.

9-cylinder Whirlwind models, up to J-5 (R-790):
* J-1: 200 hp (149 kW) @ 1800 RPM. Version of Lawrance J-1 built by Wright Aeronautical.
* J-3: 211 hp (157 kW) @ 1800 RPM. Improved version of the J-1.
* J-4: 215 hp (160 kW) @ 1800 RPM. Improvement of J-3. First to be named "Whirlwind".
* J-4A: 215 hp (160 kW) @ 1800 RPM. Modification of J-4.
* J-4B: 215 hp (160 kW) @ 1800 RPM. Improvement of J-4A.
* J-5 (R-790): 220 hp (164 kW) @ 2000 RPM. Complete redesign with much better performance and reliability.

5-cylinder R-540 models:
* J-6-5 (R-540): 150 hp (112 kW) @ 1800 RPM.
* R-540E: 175 hp (130 kW) @ 2000 RPM. Higher power from improved cylinder head.

7-cylinder R-760 models:
* J-6-7 (R-760): 225 hp (168 kW) @ 2000 RPM.
* R-760E: 250 hp (186 kW) @ 2000 RPM. Higher power from improved cylinder head.
* R-760E-1: 285 hp (213 kW) @ 2100 RPM. Higher compression ratio.
* R-760E-T: 235 hp (175 kW) @ 2000 RPM. Unsupercharged version of R-760E-1 for trainer aircraft.
* R-760E-2: 320 hp (239 kW) @ 2200 RPM, 350 hp (261 kW) @ 2400 RPM for takeoff. Increased supercharging, slightly higher compression ratio.

9-cylinder R-975 models:
* J-6-9 (R-975): 300 hp (224 kW) @ 2000 RPM.
* R-975E: 330 hp (246 kW) @ 2000 RPM. Higher power from improved cylinder head.
* R-975E-1: 365 hp (272 kW) @ 2100 RPM. Higher compression ratio.
* R-975E-3: 420 hp (313 kW) @ 2200 RPM up to 1400 ft (427 m), 450 hp (336 kW) @ 2250 RPM for takeoff. Increased supercharging, slightly higher compression ratio.
* R-975E-C2: 400 hp (298 kW) @ 2400 RPM. Built by Continental Motors under license. Designed for use in armored vehicles.

9-cylinder R-1200 Simoon
* R-1200: 350hp @ 1900 RPM. 1925. 5.5"x5.5" 1176cuin. Few built.

14-cylinder double-row experimental models:
* R-1510: 600 hp (447 kW) @ 2100 RPM.
* R-1670: 800 hp (597 kW) @ 2500 RPM. Larger bore of 5.25 in (133 mm).

Specifications

The J-6 Whirlwinds listed in the following table have the E cylinder head introduced in 1931, which gave slightly greater power than earlier versions of the J-6. [Page 13 of [http://enginehistory.org/Wright/CWthrough1940.pdf "Wright Engines - Past and Present"] (PDF), a 1940 Curtiss-Wright document available from the Aircraft Engine Historical Society.] The following table lists the final, most powerful versions of the 7-cylinder and 9-cylinder Whirlwinds.

Applications

A complete listing of every aircraft type which used Whirlwind engines would be too long to include here. The following lists show those Whirlwind-powered aircraft that were built in substantial numbers or otherwise significant.

J-5 (R-790) or earlier Whirlwinds:
*Bartel BM-5d
*Boeing NB-1 and NB-3
*Consolidated NY-1 and NY-2
*Consolidated O-17
*Consolidated PT-3
*Curtiss AT-5 and AT-5A Hawk
*Curtiss N2C-1 Fledgling
*Fairchild FC-2
*Fokker F.VIIA-3m and F.VIIB-3m
*Fokker Universal (Model 4)
*Ford Trimotor 4-AT-A and -B
*Lockheed Vega 1
*Lublin R-XI
*Lublin R-XIII
*Naval Aircraft Factory N3N-1 Canary
*New Standard D-25
*Pitcairn PA-5 Mailwing and PA-6 Super Mailwing
*PWS-18
*PWS-26
*PZL Ł.2
*Ryan B-1 Brougham
*Spirit of St. Louis
*Stearman NS-1
*Stearman C2B and C3B
*Stinson Detroiter SB-1 and SM-1
*Stinson Junior SM-2AB
*Travel Air 4000
*Vought FU
*Vought UO
*Waco 10, 10-W (ASO) and 10-T (ATO)]

5-cylinder J-6 (R-540) Whirlwinds:
*Curtiss Robin J-1
*Kreider-Reisner Challenger C-4C (Fairchild KR-34C)
*Spartan C3-165
*Stinson Junior SM-2AA
*Travel Air E-4000
*Waco BSO

7-cylinder J-6 (R-760) Whirlwinds:
*Beechcraft Staggerwing B17A, B17E
*Cessna DC-6B Scout
*Consolidated NY-3
*Curtiss N2C-2 Fledgling
*Naval Aircraft Factory N3N-3 Canary
*Stearman C3R Business Speedster
*Stinson Junior SM-2AC
*Stinson Reliant SR-8D, -8E, -9D, -9E, -10D, and -10E
*Waco CSO, CTO, CJC/DJC, CUC-1/2, CPF/DPF, DQC-6/EQC-6, and EGC-7

9-cylinder J-6 (R-975) Whirlwinds:
*Beechcraft Staggerwing B17R, C17R, and D17R
*Bellanca CH-300 Pacemaker
*Cessna DC-6A Chief
*Curtiss-Wright CW-22
*Curtiss-Wright SNC-1 Falcon
*Curtiss F9C Sparrowhawk
*Fokker Standard Universal
*Fokker T.VIII
*Ford Trimotor 4-AT-E
*Ireland N-2B Neptune
*Keystone-Loening K-84 Commuter
*North American BT-9
*Pitcairn-Cierva PCA-2 autogyro
*Ryan B-5 Brougham
*Stinson Detroiter SM-1F
*Travel Air S-6000B
*VL Pyry
*Vultee BT-15 Valiant

Continental-built R-975:

The R-975 was used in the M2 Medium Tank, M3 Medium Tank, and M4 Sherman tank, and in other armored vehicles based on their chassis, such as the M7 Priest self-propelled gun and the Canadian Ram tank and Sexton self-propelled gun. It was also used in the M18 Hellcat tank destroyer, which had a completely different chassis.

After World War II, Continental-built R-975 engines were used in the Piasecki HUP Retriever and H-25 Army Mule helicopters.

ee also

*List of aircraft engines

References

* [http://www.enginehistory.org/Wright/Wright%20J-5.pdf Wright J-5 "Whirlwind"] (PDF), by Kimble D. McCutcheon, from the Aircraft Engine Historical Society
* http://www.oldengine.org/members/diesel/Duxford/usaero16.htm
*