The Wright R-2600 Cyclone 14 (also called Twin Cyclone) is an American

radial engine The radial engine is a reciprocating engine, reciprocating type internal combustion engine, internal combustion engine configuration in which the cylinder (engine), cylinders "radiate" outward from a central crankcase like the spokes of a wheel. ...

developed by

Curtiss-Wright The Curtiss-Wright Corporation is an American 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 (business), consoli ...

, and widely used in aircraft in the 1930s and 1940s.

History

In 1935, Curtiss-Wright began work on a more powerful version of their successful R-1820 Cyclone 9. The result was the R-2600 Twin Cyclone, with 14 cylinders arranged in two rows. The R-2600-3 was originally intended for the

C-46 Commando The Curtiss C-46 Commando is a low-wing, twin-engine aircraft derived from the Curtiss CW-20 pressurized high-altitude airliner design. Early press reports used the name "Condor III" but the Commando name was in use by early 1942 in company ...

(being fitted to the prototype CW-20A). It was also the original engine choice for the

F6F Hellcat The Grumman F6F Hellcat is an American carrier-based fighter aircraft of World War II. Designed to replace the earlier F4F Wildcat and to counter the Japanese Mitsubishi A6M Zero, it was the United States Navy's dominant fighter in the second ...

; a running change (one which would not stop production) for the CW-20A, and one in late April 1942 for the second XF6F-1, led to the adoption of the

Pratt & Whitney R-2800 The Pratt & Whitney R-2800 Double Wasp is an American twin-row, 18-cylinder, air-cooled radial aircraft engine with a engine displacement, displacement of , and is part of the long-lived Pratt & Whitney Wasp series, Wasp family of engines. ...

Double Wasp in the R-2600's place for both designs. The Twin Cyclone went on to power several important American

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

aircraft, including the

A-20 Havoc The Douglas A-20 Havoc (company designation DB-7) is an American light bomber, attack aircraft, Intruder (air combat), night intruder, night fighter, and reconnaissance aircraft of World War II. Designed to meet an Army Air Corps requirement for ...

B-25 Mitchell The North American B-25 Mitchell is an American medium bomber that was introduced in 1941 and named in honor of Brigadier General William "Billy" Mitchell, a pioneer of U.S. military aviation. Used by many Allied air forces, the B-25 served ...

TBF Avenger The Grumman TBF Avenger (designated TBM for aircraft manufactured by General Motors) is an American World War II-era torpedo bomber developed initially for the United States Navy and Marine Corps, and eventually used by several air and naval av ...

SB2C Helldiver The Curtiss SB2C Helldiver was a dive bomber developed by Curtiss-Wright during World War II. As a carrier-based bomber with the United States Navy (USN), in Pacific theaters, it supplemented and replaced the Douglas SBD Dauntless. A few sur ...

, and the

PBM Mariner The Martin PBM Mariner is a twin-engine American patrol bomber flying boat of World War II and the early Cold War era. It was designed to complement the Consolidated PBY Catalina and PB2Y Coronado in service. A total of 1,366 PBMs were built ...

. Over 50,000 R-2600s were built at plants in

Paterson, New Jersey Paterson ( ) is the largest City (New Jersey), city in and the county seat of Passaic County, New Jersey, Passaic County, in the U.S. state of New Jersey.Cincinnati, Ohio Cincinnati ( ; colloquially nicknamed Cincy) is a city in Hamilton County, Ohio, United States, and its county seat. Settled in 1788, the city is located on the northern side of the confluence of the Licking River (Kentucky), Licking and Ohio Ri ...

Variants

The following is a list of known R-2600 models. Engines would receive a three-part designation from

. For example, "R-2600-1;" the "R" indicating a "

," "2600" indicating an

engine displacement Engine displacement is the measure of the cylinder volume swept by all of the pistons of a piston engine, excluding the combustion chambers. It is commonly used as an expression of an engine's size, and by extension as an indicator of the ...

of , and "1" indicating the internal model number, usually assigned chronologically. Engines accepted by the U.S. government were assigned a separate, three-part governmental designation. For example, the "R-2600-13" was accepted into service as the "GR-2600-B655;" the "GR" indicating a "(geared) radial engine," the "2600" indicating an engine displacement of , and "B655" indicating the governmental model number. The Curtiss-Wright designation is usually utilized more often than the governmental designation, and the U.S. government utilized both designations interchangeably and often together. The Curtiss-Wright designation will be listed first, followed by the — when known — governmental designation in parentheses (the lack of a governmental designation does not indicate that the model was not accepted into governmental service). Engines known only by their governmental designation will be listed at the bottom. * R-2600-1 - 1,600 hp (1,194 kW) * R-2600-2 - 1,500 hp (1,118 kW); Prototype variant; Few were made. * R-2600-3 - 1,600 hp (1,194 kW) * R-2600-4 - 1,650 hp (1,230 kW) * R-2600-6 - 1,600 hp (1,194 kW) * R-2600-8 - 1,700 hp (1,268 kW); Utilized, among other uses, by the

National Advisory Committee for Aeronautics The National Advisory Committee for Aeronautics (NACA) was a United States federal agency that was founded on March 3, 1915, to undertake, promote, and institutionalize aeronautical research. On October 1, 1958, the agency was dissolved and its ...

(NACA) to test water injection generally and in-regards to the R-2600 series, specifically. Without water injection, the R-2600-8 was capable of producing 1,700 hp (1,268 kW) at 2400 rpm for limited periods at take-off power. With water injection, testing was able to achieve 1,943 hp (1,449 kW) (maintaining the standard 2400 rpm), a 14.3% increase in power, with a fuel efficiency increase of 5%. By increasing to 2600 rpm, testing was able to achieve 2,060 hp (1,536 kW), a 21% increase in power, while providing a 4% boost in fuel efficiency. Water injection would feature heavily in mid- to late-

WWII World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

U.S. engines, including some early

jet engines A jet engine is a type of reaction engine, discharging a fast-moving jet (fluid), jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition may include Rocket engine, rocket, Pump-jet, water jet, and ...

* R-2600-8A - 1,700 hp (1,268 kW); Powered the Brewster SB2A-4 Buccaneer, 162 SB2As built for the

Kingdom of the Netherlands The Kingdom of the Netherlands (, ;, , ), commonly known simply as the Netherlands, is a sovereign state consisting of a collection of constituent territories united under the monarch of the Netherlands, who functions as head of state. The re ...

for service in the

Dutch East Indies The Dutch East Indies, also known as the Netherlands East Indies (; ), was a Dutch Empire, Dutch colony with territory mostly comprising the modern state of Indonesia, which Proclamation of Indonesian Independence, declared independence on 17 Au ...

by the

Royal Netherlands East Indies Army Air Force The Royal Netherlands East Indies Army Air Force (, ML-KNIL) was the air arm of the Royal Netherlands East Indies Army in the Dutch East Indies (now Indonesia) from 1939 until 1950. It was an entirely separate organisation from the Royal Netherl ...

. The Dutch East Indies were overrun by

Imperial Japan The Empire of Japan, also known as the Japanese Empire or Imperial Japan, was the Japanese nation state that existed from the Meiji Restoration on January 3, 1868, until the Constitution of Japan took effect on May 3, 1947. From Japan–Kor ...

in early 1942 before a single Buccaneer was delivered. The Dutch SB2As were requisitioned by the

U.S. Navy The United States Navy (USN) is the maritime service branch of the United States Department of Defense. It is the world's most powerful navy with the largest displacement, at 4.5 million tons in 2021. It has the world's largest aircraft ...

(USN). The USN provided them to the

U.S. Marine Corps The United States Marine Corps (USMC), also referred to as the United States Marines or simply the Marines, is the maritime land force service branch of the United States Department of Defense. It is responsible for conducting expeditionary ...

(USMC), complete with Dutch markings. The USN and USMC would designate these 162 models as the SB2A-4. The USMC utilized these models to establish their first

night fighter A night fighter (later known as all-weather fighter or all-weather interceptor post-Second World War) is a largely historical term for a fighter aircraft, fighter or interceptor aircraft adapted or designed for effective use at night, during pe ...

squadron,

VMF(N)-531 Marine Fighter Attack Squadron 531 (VMFA-531) was a United States Marine Corps fighter squadron consisting of various types aircraft from its inception culminating with the F/A-18 Hornet. Known as the "Grey Ghosts", the squadron participated in ...

* R-2600-9 - 1,700 hp (1,268 kW); Powered the initial production run of the

, the B-25 (24 built), B-25A (40 built), and the B-25B (designated the "Mitchell Mk.I" by the

Royal Air Force The Royal Air Force (RAF) is the Air force, air and space force of the United Kingdom, British Overseas Territories and Crown Dependencies. It was formed towards the end of the World War I, First World War on 1 April 1918, on the merger of t ...

; 23 built). The B-25C (1,625 built) would see the -9 replaced with the R-2600-13 * R-2600-10 (GR-2600-B676) - 1,700 hp (1,268 kW); Experimental high-altitude R-2600 variant with an "advanced" two-stage mechanical

supercharger In an internal combustion engine, a supercharger compresses the intake gas, forcing more air into the engine in order to produce more power for a given displacement (engine), displacement. It is a form of forced induction that is mechanically ...

, vice the usual single-stage supercharger. The 2600-10 also served as a testbed for turbo-supercharging the 2600 series (which would come to fruition with the R-2600-16). Very few were produced. The R-2600-10 powered Grumman's prototype

, the XF6F-1. The XF6F-2 would be powered by the developmentally similar R-2600-16. Grumman and the U.S. Navy were not happy with the R-2600's performance, which led to the 2,000 hp (1,491 kW)

engine replacing the R-2600 on the XF6F-3 and F6F production models. * XR-2600-10 - 1,900 hp (1,420 kW); Experimental version of the R-2600-10 uprated to 1,900 hp (1,420 kW), a 12% increase over the 1,700 hp (1,268 kW) R-2600-10. The XR-2600-10 powered two examples of the

Grumman TBF Avenger The Grumman TBF Avenger (designated TBM for aircraft manufactured by General Motors) is an American World War II-era torpedo bomber developed initially for the United States Navy and Marine Corps, and eventually used by several air and naval a ...

, the XTBF-2 (1 built) and the TBM-2 (1 built). Neither the XTBF-2, TBM-2, nor the XR-2600-10 would enter serial production * R-2600-11 - 1,600 hp (1,194 kW); * R-2600-12 (GR-2800-B766) - 1,700 hp (1,268 kW) * R-2600-13 (GR-2600-B655), 1,700 hp (1,268 kW); Powered the Brewster SB2A-4;

Curtiss P-37 The Curtiss YP-37 was an American fighter aircraft developed by Curtiss-Wright in the late 1930s for the United States Army Air Corps (USAAC). A derivative of the Curtiss P-36 Hawk, the YP-37 was designed to improve performance by replacing the ...

; Douglas A-24A/B/C; Martin A-30A/B; North American XB-25E/F/G, B-25C/D/G/H/J, CB-25J, TB-25J, and F-10; Lockheed O-56/RB-34B/B-37/RB-37; Short Brothers Stirling; and the Vultee A-35A & A-35B. The -13 would also power a maritime patrol-bomber variant of the B-25, the PBJ-1D. 13,494 R-2600-13s were built between April 1941 and January 1944 * R-2600-14 - 1,700 hp (1,268 kW); Powered at least one of the prototypes of the

Grumman F7F Tigercat The Grumman F7F Tigercat is a heavy fighter aircraft that served with the United States Navy (USN) and United States Marine Corps (USMC) from late in World War II until 1954. It was the first twin-engine fighter to be deployed by the USN. While ...

(a twin-engined

heavy fighter A heavy fighter is an historic category of fighter aircraft produced in the 1930s and 1940s, designed to carry heavier weapons or operate at longer ranges than light fighter aircraft. To achieve performance, most heavy fighters were twin-engine ...

interceptor Interceptor may refer to: Arts and entertainment Film and television * ''The Interceptor'', a British drama series on BBC One * Interceptor (game show), ''Interceptor'' (game show), a British television game show that ran during 1989 * Interc ...

), the XF7F-1. The R-2600-14 was a development of the R-2600-10 and featured "advanced

supercharging In an internal combustion engine, a supercharger compresses the intake gas, forcing more air into the engine in order to produce more power for a given displacement. It is a form of forced induction that is mechanically powered (usually by a b ...

" for high-altitude performance. The R-2600-14 was developed specifically for the Tigercat project. The engines were replaced in initial production versions by the 2,100 hp (1,566 kW) R-2800-22, ultimately trading superior high-altitude performance for the R-2800-22's significantly improved low- and medium-altitude performance. * R-2600-15 - 1,800 hp (1,342 kW); Planned to power the XB-33A, a prototype model of the B-33 Super Marauder (itself a high-altitude version of the

B-26 Marauder The Martin B-26 Marauder is an American twin-engined medium bomber that saw extensive service during World War II. The B-26 was built at two locations: Baltimore, Maryland, and Omaha, Nebraska, by the Glenn L. Martin Company. First used in t ...

). The project was cancelled, and neither the prototype XB-33A or production B-33A were ever built.Andrade 1979, p 51 * R-2600-16 - 1,700 hp (1,268 kW); Similar to the R-2600-10 & -14, the -16 was tuned for high-altitude performance; The -16 was designed to be mounted alongside a

turbo-supercharger In an internal combustion engine, a turbocharger (also known as a turbo or a turbosupercharger) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake air, forcing more air into the ...

system. The -16 would power the second Grumman F6F, the initial XF6F-2.Thruelsen 1976, p 193 The XF6F-1 and XF6F-2 was found to be lacking in performance; The XF6F-2 designation was re-used on a third prototype, an R-2800-powered XF6F-2. The R-2800 would carry-over into the final prototype, the XF6F-3, as well as production models. * R-2600-17 - 1,700 hp (1,268 kW); May have powered a

Vultee A-31 Vengeance The Vultee A-31 Vengeance is an American dive bomber of World War II that was built by Vultee Aircraft. A modified version was called A-35. The Vengeance was not used operationally by the United States but was operated as a front-line aircraft ...

(or A-35) variant. May have also powered one of the C-55 prototypes, a derivative of the

* R-2600-17A - 1,750 hp (1,305 kW); Uprated R-2600-17 * R-2600-19 (GR-2600-A5B) - 1,600 hp (1,194 kW), 1,660 hp (1,237 kW) * R-2600-20 - 1,700 hp (1,268 kW), 1,900 hp (1,420 kW) * R-2600-21 (GR-2600-A5B) - 1,500 hp (1,118 kW), 1,600 hp (1,194 kW), 1,700 hp (1,268 kW); Experimental R-2600-19 engines modified with new carburetors and cylinder baffles. -21s were "converted" back into -19s and retained their governmental GR-2600-A5B designation * R-2600-22 - 2,100 hp (1,566 kW); Powerplant of the experimental XSB2C-6 Helldiver as well as the PBM-3D Mariner. Power is referenced as low as 1,900 hp (1,418 kW) and as high as 2,100 hp (1,566 kW) * R-2600-23 (GR-2600-A5B-0) - 1,600 hp (1,194 kW), 1,675 hp (1,250 kW); The R-2600-23 required 91

octane Octane is a hydrocarbon and also an alkane with the chemical formula C8H18, and the condensed structural formula CH3(CH2)6CH3. Octane has many structural isomers that differ by the location of branching in the carbon chain. One of these isomers ...

fuel (other R-2600 models accepted higher-octane fuel). The -23 was normally rated at 1,600 hp (1,194 kW) at

sea level Mean sea level (MSL, often shortened to sea level) is an mean, average surface level of one or more among Earth's coastal Body of water, bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical ...

while at take-off power, but could be "uprated" to 1,675 hp (1,250 kW). These "uprated" -23s were utilized in the

Douglas A-20G Havoc The Douglas A-20 Havoc (company designation DB-7) is an American light bomber, attack aircraft, night intruder, night fighter, and reconnaissance aircraft of World War II. Designed to meet an Army Air Corps requirement for a bomber, it was orde ...

, the most-produced (2,850 built) A-20 model * R-2600-25 - 1,350 hp (1,007 kW) * R-2600-27 - 2,000 hp (1,491 kW) * R-2600-28 - No known information; Occasionally the 2,100 hp (1,566 kW) R-2600-22 is referred to as the R-2600-28 * R-2600-29 - 1,700 hp (1,268 kW), 1,850 hp (1,380 kW); Likely the most-produced R-2600 variant, with at least 17,848 produced. The R-2600-29 powered the B-25C and -25D (including the PB1-1J, a maritime patrol bomber variant of the B-25) as well as the A-20G and -H. An R-2600-29A is also referenced in various manuals and reports as the powerplant of the twin-engine TB-25N medium bomber trainer aircraft. The R-2600-29A is referenced interchangeably with the R-2600-35. * R-2600-31 - 1,700 hp (1,268 kW); The

Lockheed B-34 Ventura The Lockheed Ventura is a twin-engine medium bomber and patrol bomber of World War II. The Ventura first entered combat in Europe as a bomber with the RAF in late 1942. Designated PV-1 by the United States Navy (US Navy), it entered combat in ...

, originally powered by the R-2800, was chosen to be converted into a large, armed reconnaissance and observation aircraft, designated as the "O-56." This was later changed to "RB-34B," then to "B-37," and finally to " RB-37." 500 RB-37s were ordered, but the contract was cancelled after 18 were delivered. As the RB-37 was not expected to carry bomb loads, it was felt a lower-powered engine would suffice; The 2,000 hp (1,491 kW) R-2800 was replaced by either the 1,700 hp (1,268 kW) R-2600-31 or, with early models, the R-2600-13 * R-2600-33 - 1,700 hp (1,268 kW) * R-2600-34 - 2,100 hp (1,566 kW); Two R-2600-34s served as the powerplants of the early versions of the PBM-5 Mariner, before the switch-over to the R-2800 * R-2600-35 - 1,700 hp (1,268 kW), 1,850 hp (1,380 kW); An R-2600-29 or R-2600-29A modified with a Bendix Stromberg PR48A4

carburetor A carburetor (also spelled carburettor or carburetter) is a device used by a gasoline internal combustion engine to control and mix air and fuel entering the engine. The primary method of adding fuel to the intake air is through the Ventu ...

. The -29, -29A, and -35 may have been considered interchangeable to a degree. * GR-2600-A71 - 1,350 hp (1,007 kW); May have been a simplified name of the GR-2600-A71-3 * GR-2600-A71-3 - 1,600 hp (1,193 kW); Early R-2600 model, developed in late 1938 or very early 1939. Powered the North American NA-40B, a twin-engine

medium bomber A medium bomber is a military bomber Fixed-wing aircraft, aircraft designed to operate with medium-sized Aerial bomb, bombloads over medium Range (aeronautics), range distances; the name serves to distinguish this type from larger heavy bombe ...

of which only one was built. The NA-40 would lead the to

. May also be referred to as the GR-2600-A71 * GR-2600-C14 - 1,750 hp (1,304 kW)

Applications

Boeing 314 Clipper The Boeing 314 Clipper was an American long-range flying boat produced by Boeing from 1938 to 1941. One of the largest aircraft of its time, it had the range to cross the Atlantic and Pacific oceans. For its wing, Boeing re-used the design fro ...

Brewster SB2A Buccaneer The Brewster SB2A Buccaneer (Brewster Model 340), also known as the Brewster Bermuda, is a single-engined mid-wing monoplane scout bomber aircraft built by the Brewster Aeronautical Corporation for the United States Navy between 1942 and 1944. ...

Curtiss SB2C Helldiver The Curtiss SB2C Helldiver was a dive bomber developed by Curtiss-Wright during World War II. As a carrier-based bomber with the United States Navy (USN), in Pacific theaters, it supplemented and replaced the Douglas SBD Dauntless. A few su ...

Douglas A-20 Havoc The Douglas A-20 Havoc (company designation DB-7) is an American light bomber, attack aircraft, Intruder (air combat), night intruder, night fighter, and reconnaissance aircraft of World War II. Designed to meet an Army Air Corps requirement for ...

* Douglas B-23 Dragon *

Grumman F6F Hellcat The Grumman F6F Hellcat is an American Carrier-based aircraft, carrier-based fighter aircraft of World War II. Designed to replace the earlier Grumman F4F Wildcat, F4F Wildcat and to counter the Japanese Mitsubishi A6M Zero, it was the United St ...

(XF6F-1 & -2 prototypes only, pre-April 1942) *

Latécoère 631 The Latécoère 631 was a civil transatlantic flying boat built by Latécoère, the largest ever built up to its time. The boat had six piston engines, and was designed for passenger service. Ordered in the late 1930s, its first flight was in 19 ...

* Lioré et Olivier LeO 451 *

Martin Baltimore The Martin 187 Baltimore was a twin-engined light attack bomber built by the Glenn L. Martin Company in the United States as the A-30. The model was originally ordered by the French in May 1940 as a follow-up to the earlier Martin Maryland, the ...

Martin PBM Mariner The Martin PBM Mariner is a twin-engine American Maritime patrol aircraft, patrol bomber flying boat of World War II and the early Cold War era. It was designed to complement the Consolidated PBY Catalina and Consolidated PB2Y Coronado, PB2Y C ...

(versions prior to the R-2800 "Double Wasp"-powered PBM-5, though early models of the PBM-5 mounted the 2,100 hp (1,566 kW) R-2600-34) *

Miles Monitor The Miles M.33 Monitor was a twin-engined British target tug aircraft designed and built by Miles Aircraft towards the end of the Second World War. Intended for use by the Royal Air Force and the Fleet Air Arm, the aircraft did not enter service ...

North American B-25 Mitchell The North American B-25 Mitchell is an American medium bomber that was introduced in 1941 and named in honor of Brigadier General Billy Mitchell, William "Billy" Mitchell, a pioneer of U.S. military aviation. Used by many Allies of World War ...

Specifications (GR-2600-C14BB)

References

Notes

Bibliography

* * * * *

External links

{{US military piston aeroengines 1930s aircraft piston engines Aircraft air-cooled radial piston engines R-2600