Wright R-975

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Wright Aeronautical
Continental Motors
R-975 built by Continental for a Sherman tank

R-975 built by Continental for a Sherman tank
Wright R-975
Production period: 1929-1950s
Manufacturer: Wright Aeronautical
Continental Motors
Working principle: Otto
Motor design: Radial engine
Drilling: 127 mm
Hub: 140 mm
Displacement: 15980 cm 3
Mixture preparation:
Engine charging: -
Cooling system: Air cooling
Power: 220-410 kW
Dimensions: 306 kg
Previous model: R-790
Successor: none

Wright R-975 Whirlwind is a series of air-cooled nine-cylinder radial engines for aircraft that was built by the Wright Aeronautical division of the US company Curtiss-Wright . The engines have a displacement of around sixteen liters and outputs between 300  hp (221  kW ) and 450 hp (331 kW). They are the largest series-built models of the Wright Whirlwind engine family and the most numerous models were built.

During the Second World War built Continental Motors R-975 under license as the drive for the tanks of the Allies and other armored vehicles. Tens of thousands of units were produced for this purpose, rendering the use of the R-795 practically insignificant in aviation and dwarfed by the similar Pratt & Whitney R-985 . After the war, Continental built its own version of the R-975 until the 1950s. Some of these engines developed up to 550 hp (405 kW).

The R-975 was used as a powerplant for the US M18 Hellcat tank destroyer during World War II. The M18 was the fastest tracked armored vehicle until the introduction of the turbine-powered M1 Abrams in the 1980s.

construction and development

Wright introduced the J-6 Whirlwind family in 1928 as the successor to the R-790 nine-cylinder series . It consisted of engines with five, seven and nine cylinders . The nine-cylinder model was originally called the J-6 Whirlwind Nine or J-6-9 for short. However, the US government gave it the designation R-975. Wright later adopted this name.

Like all models in the J-6 Whirlwind series, the R-975 had larger cylinders than the R-790. The stroke of 140 millimeters remained unchanged, but the bore was enlarged from 114 millimeters to 127 millimeters. While the R-790 was a purely naturally aspirated engine , the R-975, like all J-6 engines, had a charge compressor to increase performance .

Wright developed the R-975 step by step, using letters appended to the designation to identify the different versions. The original R-975 (or J-6-9) developed 300  HP (221  kW ) while the R-975E from 1931 produced 330 HP (243 kW) through an improved cylinder head .

Wright later added numerical suffixes to identify the performance being given. The R-975E-1, which was presented in the same year as the R-975E, developed 365 hp (268 kW) due to better compression and a slightly increased maximum speed .

An even more powerful version, the R-975E-3, was also introduced in the same year and continuously improved. With higher boost pressure and an even higher maximum speed, the final version achieved a starting power of 450 hp (331 kW) in 1935 .

Usage history

As the most powerful series-produced motor in the Whirlwind family, it was also the most successful of the series. It was used in many general aviation aircraft such as the Beechcraft Staggerwing and in various line aircraft such as the Ford 4-AT-E Trimotor and the Lockheed 10B Electra . Furthermore, the engine powered various training aircraft of the US military such as the North American BT-9 and the Vultee BT-15 Valiant of the US Army and the Curtiss-Wright SNC Falcon of the US Navy . The Parasite Fighter Curtiss F9C Sparrowhawk was also powered by an R-975.

Russell Norton Boardman and John Louis Polando set a course record with a Wright J-6 when they flew from Floyd on April 28-30, 1931 with the Cape Cod , a Bellanca Special J-300 non-stop in 49 hours and 20 minutes Bennett Field on Long Island to Istanbul . On this flight, they covered a distance of 5,011.8  mi (8,065.7  km ).

Nevertheless, the R-975 was in strong competition to the R-985 Wasp Junior and the larger R-1340 Wasp from Pratt & Whitney , of which Pratt & Whitney R-985 was able to sell far more than Wright's R-975. The production of the R-975 was stopped in 1945 after more than 7000 units were built.

Production by Continental Motors

In 1939 the US Army , which was already using the Continental R-670 radial engine in its light tanks , commissioned Continental Motors to build the R-975 under license for use in the M2 Medium Tank . Subsequently, the same engine was used for the M3 Lee / Grant , the M4 Sherman, the Canadian Ram , the M7 self-propelled gun , the M18 Hellcat and other Allied armored vehicles . Continental's version of the R-975 for use in armored vehicles were the R-975E-C2, the R-975-C1, and the R-975-C4. In contrast to the 7,000 units built by Wright, Continental produced over 53,000 R-975 engines.

Installed in a tank lacking the engine, the cooling by traveling wind or the air stream of a propeller . Therefore a cased fan was installed, which was driven via the crankshaft to provide the same cooling.

After the war, Continental introduced its own version of the R-975 with the R9-A. Although this was basically identical to other R-975 engines and the compression and the gear ratio of the charger were not changed compared to the R-975E-3, other improvements to the R9-A led to an increase in starting power to 525 hp (386 kW), surpassing any model Wright built. A military version, the R-975-46 even achieved 550 HP (405 kW) and was used in the Piasecki HUP Retriever and H-25 Army Mule helicopters . Continental produced the R-975 until the 1950s.

Other licensed buildings

The engine was also built in Spain as the Hispano-Suiza 9Q and Hispano-Wright 9Q. Apart from the use of Hispano's patented nitrite refining process, the design remained unchanged. A single version, the 9Qdr, was equipped with a planetary gear to reduce the propeller speed. The R-975 was also built under license by Fábrica Nacional de Motores in Brazil .

variants

J-6-9 (R-975)
300 hp (221 kW) at 2000 min -1
R-975-20
300 PS (221 kW) for use in airships
R-975E
330 hp (243 kW) at 2000 min -1 ; Increased performance through improved cylinder head
R-975E-1
365 hp (268 kW) at 2100 min -1 with higher compression
R-975E-3
420 hp (309 kW) at 2200 min -1 up to a height of 1,400 ft (427 m); 450 hp (331 kW) at 2250 min -1 at the start; improved charging; slightly increased compression
R-975E-C2
400 hp (294 kW) at 2400 min -1 ; Built under license by Continental Motors for use in armored vehicles
Continental R9-A
500 hp (368 kW) at 2300 min -1 bis 4,000 ft (1,219 m); 525 hp (386 kW) at 2,300 min -1 for the start; Improved post-war version of Continental
Hispano-Suiza 9Q
License build of the R-975 J-6 Whirlwind
Hispano-Suiza 9Qa
License build of the R-975 J-6 Whirlwind
Hispano-Suiza 9Qb
License build of the R-975 J-6 Whirlwind
Hispano-Suiza 9Qc
License build of the R-975 J-6 Whirlwind
Hispano-Suiza 9Qd
License build of the R-975 J-6 Whirlwind
Hispano-Suiza 9Qdr
License build of the R-975 J-6 Whirlwind

use

Wright J-6-9 and R-975

Continental R-975

Mechanics from the Royal Army Ordnance Corps remove an R-975 tank engine

Exhibits

Web links

Commons : Wright R-975 Whirlwind  - Collection of Images

Individual evidence

  1. ↑ Don M. Fox: Patton's Vanguard: The United States Army Fourth Armored Division . McFarland, 2007, ISBN 978-0-7864-3094-9 , pp. 25 (English).
  2. ↑ a b c d e f g h i Wright Engines - Past and Present. (pdf) Curtiss-Wright, 1940, archived from the original ; accessed on January 25, 2020 (English).
  3. ↑ a b c d e f g h i Historical Engine Summary (Beginning 1930). (pdf) Curtiss-Wright, 1983, archived from the original ; accessed on January 25, 2020 (English).
  4. ↑ a b Type Certificate Data Sheet ATC 21. (pdf) Federal Aviation Administration , accessed on January 25, 2020 (English).
  5. ↑ a b Type Certificate Data Sheet TC 87. (pdf) Federal Aviation Administration , accessed on January 25, 2020 (English).
  6. ↑ a b Type Certificate Data Sheet TC 125. (pdf) Federal Aviation Administration , accessed on January 25, 2020 (English).
  7. ↑ 'Cape Cod's' Success Climaxes 5 Years [of] Bellanca Records . In: The Delmarvia Star . Wilmington, Delaware August 2, 1931, p. 6 , col. 3 (English, online [accessed February 7, 2020]).
  8. ↑ SUMMARY OF WRIGHT ENGINE SHIPMENTS 1920 - 1930. (No longer available online.) Enginehistory.org, March 3, 2016, archived from the original ; accessed on March 3, 2016 .
  9. ↑ a b Type Certificate Data Sheet E-245. (pdf) Federal Aviation Administration , accessed January 25, 2020 .
  10. ↑ Manuel Lage, SJ Sánchez-Renedo, M. Viejo: Hispano Suiza in Aeronautics: Men, Companies, Engines, and Aircraft . SAE International, 2004, ISBN 978-0-7680-0997-2 , pp. 152-163 (English).
  11. ↑ Jason Vogel: O bom caminhão a casa torna. Jornal O Globo, March 21, 2013, accessed January 25, 2020 (Portuguese).
  12. ↑ Leandro Sauerbronn: Opinião Leandro Sauerbronn: A história da Fábrica Nacional de Motores. pleno news, April 4, 2018, accessed January 25, 2020 (Portuguese).
  13. ^ Wright R-975 Whirlwind 9. Pima Air & Space Museum , archived from the original ; accessed on January 25, 2020 (eb).
  14. ^ Image Galleries by Gary and Janet Brossett: National Museum of Naval Aviation in Pensacola, Florida. enginehistory.org, archived from the original ; Retrieved December 15, 2009 .