The Wright R-975 Whirlwind was a series of nine-cylinder air-cooled

radial Radial is a geometric term of location which may refer to: Mathematics and Direction * Vector (geometric), a line * Radius, adjective form of * Radial distance, a directional coordinate in a polar coordinate system * Radial set * A bearing f ...

aircraft engines built by the

Wright Aeronautical Wright Aeronautical (1919–1929) was an American aircraft manufacturer headquartered in Paterson, New Jersey. It was the successor corporation to Wright-Martin. It built aircraft and was a supplier of aircraft engines to other builders in the ...

division of

Curtiss-Wright The Curtiss-Wright Corporation is a manufacturer and services provider headquartered in Davidson, North Carolina, with factories and operations in and outside the United States. Created in 1929 from the consolidation of Curtiss, Wright, and v ...

. These engines had a displacement of about and power ratings of . They were the largest members of the

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 nine-cylinder engines, and later expanded to incl ...

engine family to be produced commercially, and they were also the most numerous. During

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...

, Continental Motors built the R-975 under license as a powerplant for Allied tanks and other armored vehicles. Tens of thousands of engines were built for this purpose, dwarfing the R-975's usage in aircraft, where it was overshadowed by the similar Pratt & Whitney R-985. After the war, Continental continued to produce its own versions of the R-975 into the 1950s. Some of these produced as much as . The R-975 powered the American

M18 Hellcat The M18 Hellcat (officially designated the 76 mm Gun Motor Carriage M18 or M18 GMC) is a tank destroyer that was used by the United States Army in World War II and the Korean War. A top speed of up to was attained by keeping armor to a minim ...

tank destroyer which was claimed to have been the fastest tracked armored vehicle until the introduction of the turbine powered M1 Abrams in the 1980s.

Design and development

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 nine-cylinder version was originally known as the J-6 Whirlwind Nine, or J-6-9 for short. The U.S. government designated it as the R-975; Wright later adopted this and dropped the J-6 nomenclature. Like all the members of the J-6 Whirlwind family, the R-975 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-975, like the other J-6 engines, had a gear-driven supercharger to boost its power output. Wright gradually developed the R-975, at first using suffix letters to indicate successive versions. The original R-975 (or J-6-9) was rated for 300 hp (224 kW),Curtiss-Wright (1940), p. 11 while the R-975E of 1931 could do 330 hp (246 kW) thanks to an improved

cylinder head In an internal combustion engine, the cylinder head (often abbreviated to simply "head") sits above the cylinders and forms the roof of the combustion chamber. In sidevalve engines, the head is a simple sheet of metal; whereas in more modern ...

design.Curtiss-Wright (1983), p. 2Curtiss-Wright (1940), p. 13FAA Type Certificate Data Sheet ATC 21 Wright later added numeric suffixes to show different power levels. The R-975E-1, introduced the same year as the R-975E, was rated at 365 hp (272 kW) thanks to higher-compression pistons and a slightly greater

RPM Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines. Standards ISO 80000-3:2019 defines a unit of rotation as the dimensionl ...

limit.Curtiss-Wright (1940), p. 14FAA Type Certificate Data Sheet TC 87 An even more powerful version, the R-975E-3, was also introduced that year, with greater supercharging and a still higher RPM limit, and was progressively refined until the final model of 1935 could reach 450 hp (336 kW) for takeoff.Curtiss-Wright (1940), pp. 14, 16, 18FAA Type Certificate Data Sheet TC 125

Operational history

As the most powerful Whirlwind to be produced commercially was also the most successful. It powered a wide variety of civil utility aircraft, such as the

Beechcraft Staggerwing The Beechcraft Model 17 Staggerwing is an American biplane with an atypical negative wing stagger (the lower wing is farther forward than the upper wing). It first flew in 1932. Development At the height of the Great Depression, aircraft ...

, and various airliners, such as the Ford 4-AT-E Trimotor and the Lockheed 10B Electra. In addition, it powered U.S. military training aircraft including the

North American BT-9 The North American BT-9 was the United States Army Air Corps (USAAC) designation for a low-wing single engine monoplane primary trainer aircraft that served before and during World War II. It was a contemporary of the Boeing-Stearman PT-13 Kay ...

and

Vultee BT-15 Valiant The Vultee BT-13 Valiant is an American World War II-era basic (a category between primary and advanced) trainer aircraft built by Vultee Aircraft for the United States Army Air Corps The United States Army Air Corps (USAAC) was the aeri ...

for the Army and the

Curtiss-Wright SNC Falcon The Curtiss-Wright Corporation is a manufacturer and services provider headquartered in Davidson, North Carolina, with factories and operations in and outside the United States. Created in 1929 from the consolidation of Curtiss, Wright, and v ...

for the Navy. The

Curtiss F9C Sparrowhawk The Curtiss F9C Sparrowhawk is a light 1930s biplane fighter aircraft that was carried by the United States Navy airships and . It is an example of a parasite fighter, a small airplane designed to be deployed from a larger aircraft such as ...

parasite fighter A parasite aircraft is a component of a composite aircraft which is carried aloft and air launched by a larger carrier aircraft or mother ship to support the primary mission of the carrier. The carrier craft may or may not be able to later recov ...

operated from U.S. Navy airships was also powered by the R-975. One notable record set by a Wright J-6 Whirlwind-powered aircraft occurred during July 28–30, 1931, when Russell Norton Boardman and

John Louis Polando John Polando (1901–1985) was an early American aviation pioneer who, along with Russell Boardman, flew from Floyd Bennett Field to Istanbul in 1931 to set an aviation record for the longest continuous distance flown without refueling. Following ...

flew non-stop from

Floyd Bennett Field Floyd Bennett Field is an airfield in the Marine Park neighborhood of southeast Brooklyn in New York City, along the shore of Jamaica Bay. The airport originally hosted commercial and general aviation traffic before being used as a naval air ...

, on Long Island to

Istanbul, Turkey ) , postal_code_type = Postal code , postal_code = 34000 to 34990 , area_code = +90 212 (European side) +90 216 (Asian side) , registration_plate = 34 , blank_name_sec2 = GeoTLD , blank_in ...

in the ''Cape Cod'', a Bellanca Special J-300 high-wing

monoplane A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes. A monoplane has inherently the highest efficiency and lowest drag of any wing con ...

in 49:20 hours, establishing a distance record of , the first nonstop record flight to surpasse . However, the R-975 faced heavy competition from Pratt & Whitney's R-985 Wasp Junior and from their larger R-1340 Wasp. Pratt & Whitney R-985 outsold the Wright R-975 by a wide margin. Wright's production of the R-975 ceased in 1945, with over 7,000 engines being produced by the company.

Production by Continental Motors

In 1939 the U.S. Army, which had been using

Continental R-670 The Continental R-670 (factory designation W670) was a seven-cylinder four-cycle radial aircraft engine produced by Continental displacing 668 cubic inches (11 litres) and a dry weight of . Horsepower varied from 210 to 240 at 2,200 rpm. The en ...

radial engines in its light tanks, chose Continental Motors to build the R-975 under license as the engine for its M2 medium tanks. Subsequently, the same engine was selected for the M3 Lee medium tank, the

M4 Sherman } The M4 Sherman, officially Medium Tank, M4, was the most widely used medium tank by the United States and Western Allies in World War II. The M4 Sherman proved to be reliable, relatively cheap to produce, and available in great numbers. It ...

medium tank, the Canadian

Ram tank The Tank, Cruiser, Ram was a cruiser tank designed and built by Canada in the Second World War, based on the U.S. M3 Medium tank chassis. Due to standardization on the American Sherman tank for frontline units, it was used exclusively for tra ...

(which used the M3 chassis), the

M7 Priest The 105 mm Howitzer Motor Carriage M7 was an American self-propelled gun vehicle produced during World War II. It was given the official service name 105 mm Self Propelled Gun, Priest by the British Army, due to the pulpit-like machine ...

self-propelled gun, the

tank destroyer, and other Allied armored vehicles based on these. Continental versions of the R-975 for armored vehicles included the R-975E-C2, the R-975-C1, and the R-975-C4. In contrast to the 7,000 built by Wright, Continental built over 53,000 R-975 engines. When installed in a tank, the R-975 did not have the benefit of being cooled by air slipstream or propeller blast, so a cooling fan was attached to the power shaft and surrounded by a shroud to provide the same effect. After the war, Continental introduced its own R-975 version for aircraft, the R9-A. Though it was basically similar to other R-975 engines, and its compression ratio and supercharger gear ratio were unchanged from the R-975E-3, other improvements in the R9-A allowed it to achieve for takeoff,FAA Type Certificate Data Sheet E-245 surpassing any Wright version. A military version, the R-975-46, could reach , and was used in Piasecki's HUP Retriever and H-25 Army Mule helicopters. Continental's production of R-975 engines continued into the 1950s.

Other license-built R-975s

The engine was built in

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...

as the Hispano-Suiza 9Q or Hispano-Wright 9Q without modification apart from the use of Hispano's patented nitriding finishing process and, on one version only, the 9Qdr, an epicyclic output speed reducer. The R-975 was also produced under licence by

Fábrica Nacional de Motores Fábrica Nacional de Motores (FNM) was a Brazilian manufacturer of engines and motor vehicles based in the Xerém district of Duque de Caxias near Rio de Janeiro that operated between 1942 and 1988. In 2018, the manufacturer was refounded, changi ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

Variants

;J-6-9 (R-975) : at 2,000 RPM. ;R-975-20 : for airship use ;R-975E : at 2,000 RPM. Higher power from improved cylinder head. ;R-975E-1 : at 2,100 RPM. Higher compression ratio. ;R-975E-3 : at 2,200 RPM up to , at 2,250 RPM for takeoff. Increased supercharging, slightly higher compression ratio. ;R-975E-C2 : at 2,400 RPM. Built by Continental Motors under license for use in armored vehicles.Curtiss-Wright (1940), p. 19 ;Continental R9-A : at 2,300 RPM at , at 2,300 RPM for takeoff. Continental's improved post-war version. ;Hispano-Suiza 9Q :Licence built R-975 J-6 Whirlwind ;Hispano-Suiza 9Qa :variant of the Licence built R-975 J-6 Whirlwind ;Hispano-Suiza 9Qb :variant of the Licence built R-975 J-6 Whirlwind ;Hispano-Suiza 9Qc :variant of the Licence built R-975 J-6 Whirlwind ;Hispano-Suiza 9Qd :variant of the Licence built R-975 J-6 Whirlwind ;Hispano-Suiza 9Qdr :variant of the Licence built R-975 J-6 Whirlwind

Applications

Wright J-6-9 and R-975

* ASJA L2 * Avro Anson Mk IV *

B17R, C17R, and D17R * Bellanca CH-300 Pacemaker * Berliner-Joyce OJ-2 * Caribbean Traders Husky III * Cessna DC-6A Chief *

Curtiss Kingbird __NOTOC__ The Curtiss Model 55 Kingbird was an airliner built in small numbers in the United States in the early 1930s. It was a twin-engine aircraft with a fuselage derived from the single-engine Curtiss Thrush. The Kingbird had two engine nacel ...

* Curtiss-Wright CW-14 Travel Air/Speedwing/Sportsman Deluxe/Osprey *

Curtiss-Wright CW-22 The Curtiss-Wright CW-22 was a 1940s American general-purpose advanced training monoplane aircraft built by the Curtiss-Wright Corporation. It was operated by the United States Navy as a scout trainer with the designation SNC-1 Falcon. Design a ...

* Curtiss-Wright SNC-1 Falcon * de Havilland DH.75B Hawk Moth *

Dewoitine D.31 Constructions Aéronautiques Émile Dewoitine was a French aircraft manufacturer established by Émile Dewoitine at Toulouse in October 1920. The company's initial products were a range of metal parasol-wing fighters which were largely ignored by t ...

* Dewoitine D.35 * Douglas RD-1 & C-21/OA-3 Dolphin * Emsco B-5 Challenger * Goodyear K-1 *

Fokker Universal The Fokker Universal was the first aircraft built in the United States that was based on the designs of Dutch-born Anthony Fokker, who had designed aircraft for the Germans during World War I. About half of the 44 Universals that were built betwe ...

* Fokker C-5 * Fokker C-7 * Fokker C.XIV * Fokker T.VIII * Ford 4-AT-E Trimotor * Interstate XTD3R * Ireland N-2B Neptune *

Keystone XOK The Keystone XOK was an American biplane observation floatplane developed for the United States Navy during the early 1930s. Design and development In 1929, the Navy issued requirements calling for an observation floatplane intended for service a ...

* Keystone-Loening K-84 Commuter * Koolhoven F.K.56 * Lockheed Model 12B Electra Junior *

McDonnell XV-1 The McDonnell XV-1 is an experimental Convertiplane developed by McDonnell Aircraft for a joint research program between the United States Air Force and the United States Army to explore technologies to develop an aircraft that could take off a ...

Messerschmitt M 18 The Bayerische Flugzeugwerke M 18 (BFW M 18), (later known as Messerschmitt M 18) was an airliner, produced in Germany in the late 1920s. Design and development Designed at the request of Theodor Croneiss to supply his new airline venture which ...

* Noorduyn Norseman Mk.1 *

North American NA-57 The North American Aviation NA-16 was the first trainer aircraft built by North American Aviation, and was the beginning of a line of closely related North American trainer aircraft that would eventually number more than 17,000 examples, notabl ...

* North American NA-64 Yale * Pitcairn PA-19 * Pitcairn-Cierva PCA-2/OP-1 * Pitcairn PA-33 & 34/OP-2 * Ryan B-5 Brougham * Spartan C4-300 * Stearman Model 6C Cloudboy * Stinson SM-1F Detroiter * Timm T-840 * Townsend Thunderbird (as rebuilt) * Travel Air B9-4000 * Travel Air 6000B *

Travel Air Type R Mystery Ship The Type R "Mystery Ships" were a series of wire-braced, low-wing racing airplanes built by the Travel Air company in the late 1920s and early 1930s. They were so called, because the first three aircraft of the series (R614K, R613K, B11D) were bui ...

VL Pyry VL Pyry (Finnish language for ''blizzard'') was a Finnish low-winged, two-seated fighter trainer aircraft, built by the State Aircraft Factory ('' Valtion lentokonetehdas'') for use with the Finnish Air Force. The Pyry was in use from 1939 to 19 ...

* Waco JTO * Waco JYO * Waco JWM and JYM Mailplanes *

Continental R-975

The British Army in North Africa 1942 E13233

* Beech D-18C *

Grizzly I cruiser The Grizzly I was a Canadian-built M4A1 Sherman tank with relatively minor modifications, primarily to stowage and pioneer tool location and adding accommodations for a number 19 radio set. They used the same General Steel hull castings as late ...

- Canadian production of M4A1 Sherman tank *

Kangaroo Kangaroos are four marsupials from the family Macropodidae (macropods, meaning "large foot"). In common use the term is used to describe the largest species from this family, the red kangaroo, as well as the antilopine kangaroo, eastern ...

armoured personnel carrier modification of M7 Priest and other vehicles *

Kellett XR-10 The Kellett XR-10 was a military transport helicopter developed in the United States in the 1940s that only flew in prototype form. It was designed in response to a USAAF Technical Instruction issued for the development of a helicopter to transpo ...

* M3 Lee *

M12 Gun Motor Carriage The 155 mm Gun Motor Carriage M12 was a U.S. self-propelled gun developed during the Second World War. It mounted a 155 mm gun derived from the French Canon de 155mm GPF field gun. Development The idea for the M12 was first proposed i ...

M40 Gun Motor Carriage The 155 mm Gun Motor Carriage M40 was an American self-propelled artillery vehicle built on a widened and lengthened Medium Tank M4A3 chassis, but with a Continental engine and with HVSS (Horizontal Volute Spring Suspension), which was intro ...

Piasecki HUP Retriever The Piasecki HUP Retriever/H-25 Army Mule is a compact single radial engine, twin overlapping tandem rotor utility helicopter developed by the Piasecki Helicopter Corporation of Morton, Pennsylvania. Designed to a United States Navy specification ...

* Sexton self-propelled gun * Sikorsky XHJS-1 (S-53) - prototype helicopter *

Skink anti-aircraft tank Tank AA, 20 mm Quad, Skink was a Canadian self-propelled anti-aircraft gun, developed in 1943–44, in response to a requirement from the First Canadian Army. Due to a lack of threat from the German , the Skink was cancelled in 1944 after ...

- anti-aircraft vehicle based on Grizzly I

Engines on display

Some museums which have R-975 engines on display: *

Pima Air & Space Museum The Pima Air & Space Museum, located in Tucson, Arizona, is one of the world's largest non-government funded aerospace museums. The museum features a display of nearly 300 aircraft spread out over 80 acres (320,000 m²) on a campus oc ...

Tucson , "(at the) base of the black ill , nicknames = "The Old Pueblo", "Optics Valley", "America's biggest small town" , image_map = , mapsize = 260px , map_caption = Interactive map ...

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

has a Wright R-975. *

Hiller Aviation Museum The Hiller Aviation Museum is an aircraft history museum located at the San Carlos Airport in San Carlos, California. The museum was founded by Stanley Hiller in June 1998. and is endowed by members of the Hiller family. It specializes in Nor ...

in San Carlos,

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

has a Wright R-975. *

National Museum of Naval Aviation The National Naval Aviation Museum, formerly known as the National Museum of Naval Aviation and the Naval Aviation Museum, is a military and aerospace museum located at Naval Air Station Pensacola, Florida. Founded in 1962 and moved to its curr ...

near

Pensacola Pensacola () is the westernmost city in the Florida Panhandle, and the county seat and only incorporated city of Escambia County, Florida, United States. As of the 2020 United States census, the population was 54,312. Pensacola is the principal ci ...

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

has a Continental R-975. *

Southern Museum of Flight The Southern Museum of Flight is a civilian aviation museum Birmingham, Alabama. The facility features nearly 100 aircraft, as well as engines, models, artifacts, photographs, and paintings. In addition, the Southern Museum of Flight is home to ...

Birmingham Birmingham ( ) is a City status in the United Kingdom, city and metropolitan borough in the metropolitan county of West Midlands (county), West Midlands in England. It is the second-largest city in the United Kingdom with a population of 1. ...

Alabama (We dare defend our rights) , anthem = "Alabama" , image_map = Alabama in United States.svg , seat = Montgomery , LargestCity = Huntsville , LargestCounty = Baldwin County , LargestMetro = Greater Birmingham , area_total_km2 = 135,765 ...

has a Continental R-975. *

Queensland Air Museum The Queensland Air Museum is a not-for-profit community-owned aviation museum located at Caloundra Airport in Queensland, Australia. Its mission is to collect and preserve all aspects of aviation heritage with an emphasis on Australia and Queens ...

Caloundra Caloundra ( ) is a coastal town and the southernmost town in the Sunshine Coast Region in South East Queensland, Australia. Geography Caloundra is north of the Brisbane central business district. Caloundra is accessible from Landsborough ...

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , establishe ...

, Australia has a Continental R-975.. This page has
photo of a Continental R-975
* Lake Boga Catalina Museum (Lake Boga, Victoria, Australia) has a Continental Wright R-975.

Specifications (Whirlwind R-975E-3)

References

Notes

Bibliography

*. Available from the Aircraft Engine Historical Society'

* *. Available from the Aircraft Engine Historical Society'

The following

Federal Aviation Administration The Federal Aviation Administration (FAA) is the largest transportation agency of the U.S. government and regulates all aspects of civil aviation in the country as well as over surrounding international waters. Its powers include air traffic ...

type certificate A type certificate signifies the airworthiness of a particular category of aircraft, according to its manufacturing design (''type design''). It confirms that the aircraft of a new type intended for serial production, is in compliance with applica ...

data sheets, all available from the FAA'
Regulatory and Guidance Library
*R-975E: . *R-975E-1: . *R-975E-3: . *Continental R9-A: .

External links

* Engine Data Sheets: US Aero Engines �

{{US military piston aeroengines Aircraft air-cooled radial piston engines R-975 1920s aircraft piston engines Tank engines