Pratt & Whitney R-2800
Encyclopedia
The Pratt & Whitney
R-2800 Double Wasp is a two-row, 18-cylinder, air-cooled radial aircraft
engine with a displacement
of 2,804 in³ (46 L), and is part of the long-lived Wasp
family.
The R-2800 is considered one of the premier radial piston engine
s ever designed and is notable for its widespread use in many important American aircraft during and after World War II
. During the war years, Pratt & Whitney continued to develop new ideas to upgrade this already powerful workhorse, most notably water injection
to give emergency power in combat.
of 3,442 in³ (56.4 L), but it was much smaller and heat dissipation was a greater problem. To enable more efficient cooling, the usual practice of casting or forging the cylinder head cooling fins that had been effective enough for other engine designs was discarded, and instead, much thinner and closer-pitched cooling fins were machined from the solid metal of the head forging. The fins were all cut at the same time by a gang of milling saws, automatically guided as it fed across the head in such a way that the bottom of the grooves rose and fell to make the roots of the fins follow the contour of the head. Cylinder cooling was effected by aluminium cooling muffs that were shrunk onto the steel alloy forged barrels. In addition to requiring a new cylinder head design, the Double Wasp was probably the most difficult to effectively direct a flow of cooling air around.
In 1939, when the R-2800 was introduced it was capable of producing 2000 hp, for a specific power
value of 0.71 hp/in³ (32.6 kW/L). No other air-cooled engine came close to this figure, and even liquid-cooled ones barely matched it. The designing of conventional air-cooled radial engines had become so scientific and systematic by then that the Double Wasp was introduced at a power rating that was not amenable to anything like the developmental power increases that had been common with earlier engines. Nevertheless, in 1941 the power output of production models increased to 2100 hp, and to 2400 hp late in the war. However, even more was coaxed from experimental models, with fan-cooled subtypes producing 2800 hp, but in general the R-2800 was a rather highly developed powerplant right from the beginning.
The R-2800 was used to power several types of fighters and medium bombers during the war, notably the US Navy's F4U Corsair
, with the first prototype Corsair becoming the first-ever single-engine US fighter plane to exceed 400 mph (640 km/h) in level flight during October 1940. The R-2800 also powered the Corsair's naval rival, the Grumman F6F Hellcat
, the US Army Air Forces
' P-47 Thunderbolt
, and the twin-engined B-26 Marauder
and A-26 Invader
. When the US entered the war in December 1941 there were very quickly some major changes in philosophy, and such long-established engines as the Wright Cyclone
and Double Wasp were re-rated on fuel of much higher octane rating
(anti-knock
value) to give considerably more power, and by 1944 versions of the R-2800 powering late-model P-47s (and other aircraft) had a rating (experimental) of 2,800 hp on 115-grade
fuel with water injection.
After World War II, the engine was used in the Korean War
, and surplus World War II aircraft powered by the Double Wasp served with other countries well past the Korean War, some being retired as late as the latter part of the 1960s when the aircraft were replaced.
, Martin 4-0-4
, and Convair
transports. This last application is noteworthy, since these were twin-engine aircraft of size, passenger capacity, and high wing loading comparable with the DC-4
and the first Constellations
.
Today, more than seventy years after the first Double Wasp was built, it is still used in many restored vintage warbird
aircraft displayed at air show
s, and sees frequent service worldwide on aircraft such as the Canadair CL-215
water-bomber. A total of 125,334 R-2800 engines were produced between 1939 and 1960.
injection
equipment, used to increase power for short periods. Suffixes such as -S14A-G denote engines developed for export to other countries.
Pratt & Whitney
Pratt & Whitney is a U.S.-based aerospace manufacturer with global service operations. It is a subsidiary of United Technologies Corporation . Pratt & Whitney's aircraft engines are widely used in both civil aviation and military aviation. Its headquarters are in East Hartford, Connecticut, USA...
R-2800 Double Wasp is a two-row, 18-cylinder, air-cooled radial aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
engine with a displacement
Engine displacement
Engine displacement is the volume swept by all the pistons inside the cylinders of an internal combustion engine in a single movement from top dead centre to bottom dead centre . It is commonly specified in cubic centimeters , litres , or cubic inches...
of 2,804 in³ (46 L), and is part of the long-lived Wasp
Pratt & Whitney Wasp
-External links:*...
family.
The R-2800 is considered one of the premier radial piston engine
Radial engine
The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders point outward from a central crankshaft like the spokes on a wheel...
s ever designed and is notable for its widespread use in many important American aircraft during and after World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. During the war years, Pratt & Whitney continued to develop new ideas to upgrade this already powerful workhorse, most notably water injection
Water injection (engines)
In internal combustion engines, water injection, also known as anti-detonant injection, is spraying water into the cylinder or incoming fuel-air mixture to cool the combustion chambers of the engine, allowing for greater compression ratios and largely eliminating the problem of engine knocking...
to give emergency power in combat.
Design and development
First run in 1937, the R-2800 was America's first 18-cylinder radial engine design. The Double Wasp was more powerful than the world's only other modern eighteen, the Gnome-Rhône 18LGnome-Rhône 18L
-References:* Gunston, Bill. . World Encyclopaedia of Aero Engines. Patrick Stephens: Wellingborough. p.84* http://www.oldengine.org/members/diesel/Duxford/fraero2.htm...
of 3,442 in³ (56.4 L), but it was much smaller and heat dissipation was a greater problem. To enable more efficient cooling, the usual practice of casting or forging the cylinder head cooling fins that had been effective enough for other engine designs was discarded, and instead, much thinner and closer-pitched cooling fins were machined from the solid metal of the head forging. The fins were all cut at the same time by a gang of milling saws, automatically guided as it fed across the head in such a way that the bottom of the grooves rose and fell to make the roots of the fins follow the contour of the head. Cylinder cooling was effected by aluminium cooling muffs that were shrunk onto the steel alloy forged barrels. In addition to requiring a new cylinder head design, the Double Wasp was probably the most difficult to effectively direct a flow of cooling air around.
In 1939, when the R-2800 was introduced it was capable of producing 2000 hp, for a specific power
Specific power
In physics and engineering, surface power density or sometimes simply specific power is power per unit area.-Applications:* The intensity of electromagnetic radiation can be expressed in W/m2...
value of 0.71 hp/in³ (32.6 kW/L). No other air-cooled engine came close to this figure, and even liquid-cooled ones barely matched it. The designing of conventional air-cooled radial engines had become so scientific and systematic by then that the Double Wasp was introduced at a power rating that was not amenable to anything like the developmental power increases that had been common with earlier engines. Nevertheless, in 1941 the power output of production models increased to 2100 hp, and to 2400 hp late in the war. However, even more was coaxed from experimental models, with fan-cooled subtypes producing 2800 hp, but in general the R-2800 was a rather highly developed powerplant right from the beginning.
The R-2800 was used to power several types of fighters and medium bombers during the war, notably the US Navy's F4U Corsair
F4U Corsair
The Vought F4U Corsair was a carrier-capable fighter aircraft that saw service primarily in World War II and the Korean War. Demand for the aircraft soon overwhelmed Vought's manufacturing capability, resulting in production by Goodyear and Brewster: Goodyear-built Corsairs were designated FG and...
, with the first prototype Corsair becoming the first-ever single-engine US fighter plane to exceed 400 mph (640 km/h) in level flight during October 1940. The R-2800 also powered the Corsair's naval rival, the Grumman F6F Hellcat
F6F Hellcat
The Grumman F6F Hellcat was a carrier-based fighter aircraft developed to replace the earlier F4F Wildcat in United States Navy service. Although the F6F resembled the Wildcat, it was a completely new design powered by a 2,000 hp Pratt & Whitney R-2800. Some tagged it as the "Wildcat's big...
, the US Army Air Forces
United States Army Air Forces
The United States Army Air Forces was the military aviation arm of the United States of America during and immediately after World War II, and the direct predecessor of the United States Air Force....
' P-47 Thunderbolt
P-47 Thunderbolt
Republic Aviation's P-47 Thunderbolt, also known as the "Jug", was the largest, heaviest, and most expensive fighter aircraft in history to be powered by a single reciprocating engine. It was heavily armed with eight .50-caliber machine guns, four per wing. When fully loaded, the P-47 weighed up to...
, and the twin-engined B-26 Marauder
B-26 Marauder
The Martin B-26 Marauder was a World War II twin-engine medium bomber built by the Glenn L. Martin Company. First used in the Pacific Theater in early 1942, it was also used in the Mediterranean Theater and in Western Europe....
and A-26 Invader
A-26 Invader
The Douglas A-26 Invader was a United States twin-engined light attack bomber built by the Douglas Aircraft Co. during World War II that also saw service during several of the Cold War's major conflicts...
. When the US entered the war in December 1941 there were very quickly some major changes in philosophy, and such long-established engines as the Wright Cyclone
Wright Cyclone
Wright Cyclone was the name given to a family of air-cooled radial piston engines designed by Curtiss-Wright and used in numerous American aircraft in the 1930s and 1940s.-Background:...
and Double Wasp were re-rated on fuel of much higher octane rating
Octane rating
Octane rating or octane number is a standard measure of the anti-knock properties of a motor or aviation fuel. The higher the octane number, the more compression the fuel can withstand before detonating...
(anti-knock
Engine knocking
Knocking in spark-ignition internal combustion engines occurs when combustion of the air/fuel mixture in the cylinder starts off correctly in response to ignition by the spark plug, but one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front.The...
value) to give considerably more power, and by 1944 versions of the R-2800 powering late-model P-47s (and other aircraft) had a rating (experimental) of 2,800 hp on 115-grade
Octane rating
Octane rating or octane number is a standard measure of the anti-knock properties of a motor or aviation fuel. The higher the octane number, the more compression the fuel can withstand before detonating...
fuel with water injection.
After World War II, the engine was used in the Korean War
Korean War
The Korean War was a conventional war between South Korea, supported by the United Nations, and North Korea, supported by the People's Republic of China , with military material aid from the Soviet Union...
, and surplus World War II aircraft powered by the Double Wasp served with other countries well past the Korean War, some being retired as late as the latter part of the 1960s when the aircraft were replaced.
Peace time
Engines naturally grow in power with development, but a major war demands the utmost performance from engines fitted to aircraft whose life in front-line service was unlikely to exceed 50 hours' flying, over a period of only a month or two. In peace time however, the call was for reliability over a period of perhaps a dozen years, and the R-2800's reliability commended its use for long-range patrol aircraft and for the Douglas DC-6Douglas DC-6
The Douglas DC-6 is a piston-powered airliner and transport aircraft built by the Douglas Aircraft Company from 1946 to 1958. Originally intended as a military transport near the end of World War II, it was reworked after the war to compete with the Lockheed Constellation in the long-range...
, Martin 4-0-4
Martin 4-0-4
|-See also:-Bibliography:* Andrade, John. U.S. Military Aircraft Designations and Serials since 1909. Leicester, UK: Midland Counties Publications, 1979, pp. 95, 217. ISBN 0-904597-22-9....
, and Convair
Convair 240
The Convair CV-240 was an American airliner produced by Convair from 1947 to 1954, initially as a possible replacement of the ubiquitous Douglas DC-3. While featuring a more modern design, the 240 series was able to make some inroads as a commercial airliner and also had a long development cycle...
transports. This last application is noteworthy, since these were twin-engine aircraft of size, passenger capacity, and high wing loading comparable with the DC-4
Douglas DC-4
The Douglas DC-4 is a four-engined propeller-driven airliner developed by the Douglas Aircraft Company. It served during World War II, in the Berlin Airlift and into the 1960s in a military role...
and the first Constellations
Lockheed Constellation
The Lockheed Constellation was a propeller-driven airliner powered by four 18-cylinder radial Wright R-3350 engines. It was built by Lockheed between 1943 and 1958 at its Burbank, California, USA, facility. A total of 856 aircraft were produced in numerous models, all distinguished by a...
.
Today, more than seventy years after the first Double Wasp was built, it is still used in many restored vintage warbird
Warbird
Warbird is a term used, predominantly in North America, to describe vintage military aircraft.- Naming :Although the term originally implied piston-driven aircraft from the World War II era, it is now often extended to include all military aircraft, including jet-powered aircraft, that are no...
aircraft displayed at air show
Air show
An air show is an event at which aviators display their flying skills and the capabilities of their aircraft to spectators in aerobatics. Air shows without aerobatic displays, having only aircraft displayed parked on the ground, are called "static air shows"....
s, and sees frequent service worldwide on aircraft such as the Canadair CL-215
Canadair CL-215
The Canadair CL-215 was the first model in a series of firefighting flying boat amphibious aircraft built by Canadair and later Bombardier. The CL-215 is a twin-engine, high-wing aircraft designed to operate well at low speed and in gust-loading circumstances, as are found over forest fires...
water-bomber. A total of 125,334 R-2800 engines were produced between 1939 and 1960.
Variants
Note: The suffix W eg: -10W denotes engines using waterinjection
Water injection (engines)
In internal combustion engines, water injection, also known as anti-detonant injection, is spraying water into the cylinder or incoming fuel-air mixture to cool the combustion chambers of the engine, allowing for greater compression ratios and largely eliminating the problem of engine knocking...
equipment, used to increase power for short periods. Suffixes such as -S14A-G denote engines developed for export to other countries.
- R-2800-2SB-G - 1,850 hp (1,379 kW)
- XR-2800-4 - 1,805 hp (1,350 kW)
- R-2800-5 - 1,850 hp (1,379 kW)
- R-2800-8 - 2,000 hp (1,491 kW)
- R-2800-8(B) - 2,000 hp (1,491 kW)
- R-2800-8W - 2,250 hp (1,677 kW)
- R-2800-9 - 2,000 hp (1,491 kW)
- R-2800-10 - 2,000 hp (1,491 kW)
- R-2800-10W - 2,200 hp (1,640 kW)
- R-2800-18W - 2,450 hp (1,827 kW)
- R-2800-21 - 2,000 hp (1,491 kW)
- R-2800-21W - 2,300 hp (1,700 kW)
- R-2800-22W - 2,400 hp (1,789 kW)
- R-2800-27 - 2,000 hp (1,491 kW)
- R-2800-30W - 2,250 hp (1,677 kW)
- R-2800-31 - 2,000 hp (1,491 kW)
- R-2800-32(E) - 2,450 hp (1,827 kW), 2,850 hp (2,125 kW) with water-methanol injection
- R-2800-34 - 2,100 hp (1,567 kW)
- R-2800-34W - 2,400 hp (1,789 kW)
- R-2800-39 - 2,000 hp (1,491 kW)
- R-2800-41 - 2,000 hp (1,491 kW)
- R-2800-43 - 2,000 hp (1,491 kW)
- R-2800-44 - 2,300 hp (1,700 kW)
- R-2800-44W - 2,400 hp (1,789 kW)
- R-2800-48 - 2,500 hp (1,890 kW)
- R-2800-48W - 2,400 hp (1,789 kW)
- R-2800-51 - 2,000 hp (1,491 kW)
- R-2800-54 - 2,100 hp (1,567 kW)
- R-2800-57 - 2,800 hp (2,090 kW)
- R-2800-57C - 2,800 hp (2,090 kW)
- R-2800-59 - 2,300 hp (1,700 kW)
- R-2800-59W - 2,500 hp (1,890 kW)
- R-2800-65 - 2,000 hp (1,491 kW)
- R-2800-65W - 2,250 hp (1,677 kW)
- R-2800-71 - 2,000 hp (1,491 kW)
- R-2800-73 - 2,800 hp (2,090 kW)
- R-2800-75 - 2,200 hp (1,640 kW)
- R-2800-77 - 2,800 hp (2,090 kW)
- R-2800-79 - 2,000 hp
- R-2800-83 - 2,100 hp (1,567 kW)
- R-2800-83AM - 2,100 hp (1,567 kW)
- R-2800-99W - 2,300 hp (1,700 kW)
- R-2800-103W - 2,500 hp (1,890 kW)
- R-2800-CB16 - 2,400 hp (1,789 kW), 2,500 hp (1,890 kW)
- R-2800-CB17 - 2,500 hp (1,890 kW)
- R-2800-S1A4-G - 1,850 hp (1,379 kW)
- R-2800-S1C3-G - 2,100 hp (1,567 kW)
Applications
The following is a partial list of aircraft that were powered by the R-2800 (and a few prototypes that utilized it at one point):- Brewster XA-32Brewster XA-32-References:* McCullough, Anson. "Grind 'Em Out Ground Attack: The Search for the Elusive Fighter Bomber." Wings, Vol. 25, No. 4, August 1995.-External links:* * *...
- Breguet Deux-PontsBreguet Deux-PontsThe Breguet 761/763/765 were a family of 1940s and 1950s French double-deck transport aircraft produced by Breguet. The aircraft were normally called the Deux-Ponts but it was not an official name.-Design and development:...
- Canadair CL-215Canadair CL-215The Canadair CL-215 was the first model in a series of firefighting flying boat amphibious aircraft built by Canadair and later Bombardier. The CL-215 is a twin-engine, high-wing aircraft designed to operate well at low speed and in gust-loading circumstances, as are found over forest fires...
- Canadair C-5 North StarCanadair North StarThe Canadair North Star was a 1940s Canadian development of the Douglas C-54 / DC-4 aircraft. Instead of radial piston engines found on the Douglas design, Canadair employed Rolls-Royce Merlin engines in order to achieve a 35 mph faster cruising speed. The prototype flew on 15 July 1946 and...
- Consolidated TBY Sea Wolf
- Convair 240, 340 and 440
- Curtiss P-60Curtiss P-60The Curtiss P-60 was a 1940s United States single-engine single-place, low-wing monoplane fighter aircraft developed by the Curtiss-Wright company as a successor to their P-40. It went through a lengthy series of prototype versions, eventually evolving into a design that bore little resemblance to...
- Curtiss XF15CCurtiss XF15C-External links:* * *...
- Curtiss C-46 Commando
- Douglas A-26 Invader
- Douglas DC-6Douglas DC-6The Douglas DC-6 is a piston-powered airliner and transport aircraft built by the Douglas Aircraft Company from 1946 to 1958. Originally intended as a military transport near the end of World War II, it was reworked after the war to compete with the Lockheed Constellation in the long-range...
- Fairchild C-82 Packet
- Fairchild C-123 Provider
- Grumman AF Guardian
- Grumman F6F Hellcat
- Grumman F7F Tigercat
- Grumman F8F Bearcat
- Howard 500Howard 500-External Sources:* * * - Development of Howard 500 model for Microsoft Flight Simulator, with extensive detail, photographs, and movies of real aircraft.-Aircraft Videos:* * *...
- Lockheed Ventura/B-34 Lexington/PV-1 Ventura/PV-2 HarpoonLockheed VenturaThe Lockheed Ventura was a bomber and patrol aircraft of World War II, used by United States and British Commonwealth forces in several guises...
- Lockheed XC-69E ConstellationLockheed C-69 ConstellationThe Lockheed C-69 Constellation was the first military version of the Lockheed Constellation aircraft line. It first flew in 1943, and only 22 were ever constructed for the United States Army Air Forces...
- Martin B-26 Marauder
- Martin 2-0-2Martin 2-0-2The Martin 2-0-2 was one of the first modern airliners. The twin-engined piston aircraft was designed and built by the Glenn L. Martin Company.-Design and development:...
- Martin 4-0-4Martin 4-0-4|-See also:-Bibliography:* Andrade, John. U.S. Military Aircraft Designations and Serials since 1909. Leicester, UK: Midland Counties Publications, 1979, pp. 95, 217. ISBN 0-904597-22-9....
- North American AJ Savage
- North American XB-28
- Northrop XP-56 Black Bullet
- Northrop P-61 Black Widow
- Northrop F-15 Reporter
- Republic P-47 Thunderbolt
- Sikorsky CH-37 Mojave
- Sikorsky S-60Sikorsky S-60|-See also:-References:NotesBibliography* Donald, David, ed. The Complete Encyclopedia of World Aircraft. New York: Barnes & Noble, 1997. ISBN 0-7607-0592-5....
- Vickers WarwickVickers WarwickThe Vickers Warwick was a multi-purpose British aircraft used during the Second World War. Built by Vickers-Armstrongs at Brooklands, Surrey, the Warwick was used by the Royal Air Force as a transport, air-sea rescue and maritime reconnaissance platform, and by the civilian British Overseas...
- Vought F4U Corsair
- Vultee YA-19BVultee A-19The Vultee V-11 and V-12 were American attack aircraft of the 1930s. Developments of the Vultee V-1 single-engined airliner, the V-11 and V-12 were purchased by several nation's armed forces, including China, who used them in combat against Japanese forces in the Second Sino-Japanese War...
Specifications (R-2800-54)