Sunday, July 06, 2008
American Iron: What made the USA Great; The Chance Vought F4U Corsair
Name: Chance Vought F4U Corsair
DOB: When "BuAer" sent its proposal for a high performance, carrier based fighter to United Aircraft Corporation (parent company of Vought-Sikorsky) on February 1, 1938, it seemed the Navy might have pushed technology to the point of giving it a hernia. C. J. McCarthy, who was Vought’s General Manager, called in the company’s chief engineer, Rex Beisel. Rex was one of those people who lived by the old motto "The difficult we do immediately. The impossible will take a week, ten days at the most."
Occupation: longest production run of any piston-engined fighter in U.S. history (1942–1952)
Hometown: May 1, 1940 and five months later flew the 45 miles (73 km) between Stratford and Hartford, Connecticut at a speed of 405 miles per hour (651.8 kph), becoming the first production aircraft to exceed 400 mph in level flight.
Current residence: Various Collectors and other's who love this plane.
Why this is great American Iron: The Chance Vought F4U Corsair was a carrier-capable fighter aircraft that saw service in World War II and the Korean War (and in isolated local conflicts). Goodyear-built Corsairs were designated FG and Brewster-built aircraft F3A. The Corsair served in some air forces until the 1960s, following the longest production run of any piston-engined fighter in U.S. history (1942–1952 Some Japanese pilots regarded it as the most formidable American fighter of World War II. The U.S. Navy counted an 11:1 kill ratio for every F4U shot down.
The Corsair was designed by Rex Beisel and Igor Sikorsky, and incorporated the largest engine available at the time, the 2,000 hp (1,490 kW) 18-cylinder Pratt & Whitney R-2800 Double Wasp radial. To extract as much power as possible, a relatively large, 13 ft, 4 inch (4.06 m) Hamilton Standard Hydromatic three-blade propeller was used. To accommodate a folding wing, the designers considered retracting the main landing gear rearward, but for the chord of wing selected, it was difficult to fit gear struts long enough to provide sufficient clearance for the large propeller. Their solution was an inverted gull wing, the same layout used as Germany's infamous Stuka dive bomber, considerably shortening the length of the main gear legs The "bend" in the wing also permitted the wing and fuselage to meet at the optimum angle for minimizing drag. Offsetting these benefits, the bent wing was more difficult to construct and would weigh more than a straight one.
The 2,000 hp (1,500 kW) Pratt & Whitney R-2800-8 in a Goodyear FG-1 CorsairThe Corsair's aerodynamics were an advancement over contemporary naval fighters. The F4U was the first U.S. Navy airplane to feature landing gear that retracted fully, exactly in the manner of the Curtiss P-40 in rotating through 90° during retraction with the wheel atop the lower end of the strut, leaving a completely streamlined wing. Air intakes used slots in the leading edges of the wings rather than protruding scoops. Panels were attached with flush rivets, and the design took advantage of the newly-developed technique of spot welding. While employing this new technology, the Corsair was also the last American-produced fighter aircraft to feature fabric covered control surfaces, which were used for the top and bottom of each outer wing and the elevator surfaces. (The later Boeing B-29 bomber used a fabric-covered rudder.) Even with its streamlining and high speed abilities, with full flap deployment of 60 degrees the Corsair could fly slowly enough for carrier landings.
In part because of its advances in technology and a top speed greater than existing Navy aircraft, numerous technical problems had to be solved before the Corsair would enter service. Carrier suitability was a major development issue, prompting changes to the main landing gear, tail wheel and tailhook. Early prototypes had difficulty recovering from developed spins, since the inverted gull wing's shape interfered with elevator authority. A small spoiler was added to the leading edge of the starboard wing to reduce adverse stall characteristics.
Underside of a Corsair The combination of an aft cockpit and the Corsair's long nose made landings hazardous for newly-trained pilots. The cockpit position in the prototype was 36 in (91 cm) further forward, but a desire for more powerful armament necessitated changes. Putting three 50 caliber guns in each outer wing panel eliminated fuel tanks there, and the fuselage tank above the wings was enlarged to compensate. This required that the seat be moved rearward, behind the tank, an arrangement used in other piston fighters of the era. Because the more docile, and simpler to build, F6F Hellcat was coming into service, Corsair deployment aboard U.S. carriers could be delayed. Following Vought modifications to the landing gear, repositioning of the seat, addition of the stall block to the starboard wing, and after a landing technique using a curving approach was developed by the British Royal Navy that kept the LSO (landing signal officer) in view while coming aboard, Corsairs entered U.S. carrier service toward the end of 1944.
United States Navy and Marine Corps
In February 1938, the U.S. Navy Bureau of Aeronautics published two requests for proposal, for twin-engined and single-engined fighters. For the single-engined fighter the Navy requested the maximum obtainable speed, and a stalling speed not higher than 70 mph (113 km/h). A range of 1,000 miles (1,610 km) was specified. The fighter had to carry four guns, or three with increased ammunition. Provision had to be made for anti-aircraft bombs to be carried in the wing. These small bombs would, according to thinking in the 1930s, be dropped on enemy aircraft formations.
In June 1938, the USN signed a contract for a prototype, the XF4U-1, BuNo 1443. After mock-up inspection in February 1939 construction of the XF4U-1 powered by an XR-2800-4 engine, rated at 1,805 hp (1,350 kW) went ahead quickly. The first flight of the XF4U-1 was made on 29 May 1940, with Lyman A. Bullard Jr. at the controls. The maiden flight was eventful; a hurried landing was made when the elevator trim tabs failed because of flutter.
On 1 October, the XF4U-1 made a flight from Stratford to Hartford with an average ground speed of 405 mph (650 km/h), the first U.S. fighter to fly faster than 400 mph (640 km/h). The XF4U-1 also had an excellent rate of climb. On the other hand, the testing of the XF4U-1 revealed some requirements would have to be rewritten. In full-power dive tests, speeds of up to 550 mph (885 km/h) were achieved, not without damage to the control surfaces and access panels, and, in one case, an engine failure. The spin recovery standards also had to be relaxed, as recovery from the required two-turn spin proved impossible without recourse to an anti-spin chute. The problems clearly meant delays in getting the type into production.
Reports coming back from the war in Europe indicated that an armament of two .30 caliber (7.62 mm) and two .50 caliber (12.7 mm) machine guns was insufficient, and so when the U.S. Navy asked for production proposals in November 1940, heavier armament was specified. The Navy entered into a letter of intent on 3 March 1941, received Vought's production proposal on 2 April, and awarded Vought a contract for 584 F4U-1 fighters on 30 June of the same year. On 25 June 1942 Boone Guyton flew the production F4U-1 on its maiden flight. Brewster and Goodyear were already tooling up to join the Corsair production program, having been selected in late 1941 as additional contractors for the aircraft.
Corsair losses in World War II were as follows:
By combat: 189
By enemy anti-aircraft artillery: 349
Accidents during combat missions: 230
Accidents during non-combat flights: 692
Destroyed aboard ships or on the ground: 164
One particularly interesting kill was scored by a Marine Lieutenant R.R. Klingman of VMF-312 Checkerboards, over Okinawa. Klingman was in pursuit of a Kawasaki Ki-45 Toryu ("Nick") twin engine fighter at extremely high altitude when his guns jammed due to the gun lubrication thickening from the extreme cold. He simply flew up and chopped off the Ki-45's tail with the big propeller of the Corsair. Despite missing five inches (127 mm) off the end of his propeller blades, he managed to land safely. He was awarded the Navy Cross.
During the Korean War, the Corsair was used mostly in the close-support role. The AU-1 Corsair was a ground-attack version produced for the Korean War; its Pratt & Whitney R-2800 engine, while supercharged, was not as highly "blown" as on the F4U. As the Corsair moved from its air superiority role in World War II into the close air support role in the Korean Conflict, the gull wing proved to be a useful feature. A straight, low-wing design would have blocked most of the visibility from the cockpit toward the ground while in level flight, but a Corsair pilot could look through a "notch" and get a better ground reference without having to bank one way or the other to move the wing out of the way.
The AU-1, F4U-4B, -4C, -4P, and -5N logged combat in Korea between 1950 and 1953. There were dogfights between F4Us and Soviet-built Yakovlev Yak-9 fighters early in the conflict, but when the enemy introduced the Mikoyan-Gurevich MiG-15, the Corsair was outmatched, though one Marine pilot did get lucky. On 10 September 1952, a MiG-15 made the mistake of getting into a turning contest with a Corsair piloted by Captain Jesse G. Folmar, with Folmar shooting the MiG down with his four 20 millimeter cannon. The MiG's wingmen quickly had their revenge, shooting down Folmar, though he bailed out and was swiftly rescued with little injury.
Corsair night fighters were used to an extent. The enemy adopted the tactic of using low-and-slow Polikarpov Po-2 intruders to perform night harassment strikes on American forces, and jet-powered night fighters found catching these "Bedcheck Charlies" troublesome. U.S. Navy F4U-5Ns were posted to shore bases to hunt them down, with U.S. Navy Lieutenant Guy Pierre Bordelon, Jr. becoming the Navys only ace in the conflict, as well as the only ace to not score any victories in a jet plane.
More generally, Corsairs performed attacks with cannon, napalm tanks, various iron bombs and unguided rockets. The old HVAR was a reliable standby, however sturdy Soviet-built armor proved resistant to the HVAR's punch leading to a new 6.5 in (16.5 cm) hollow-charge antitank warhead being developed. The result was called the "Anti-Tank Aircraft Rocket." The big 11.75 inch (29.8 cm) Tiny Tim was also used in combat, with two under the belly. There is a story of a Corsair pilot who cut enemy communications lines by snagging them with his arresting hook.
Lieutenant Thomas J. Hudner, Jr., flying with naval squadron VF-32 off the USS Leyte, was awarded the Medal of Honor for crash landing his Corsair in an attempt to rescue his squadron mate, Ensign Jesse L. Brown, whose aircraft had been forced down by antiaircraft fire near Changjin.
FAA introduced the Corsair into carrier service before the USN. British units solved the landing visibility problem by approaching the carrier in a medium left-hand turn, which allowed the pilot to keep the carrier's deck in view over the dip in the port wing, allowing safe carrier operations.
In the early days of the war, RN fighter requirements had been based on cumbersome two-seat designs, such as the Blackburn Skua, Fairey Fulmar, and Fairey Firefly, on the assumption they would only be fighting long range bombers or flying boats. The RN hurriedly adopted higher performance but less robust types derived from land based aircraft, such as the Supermarine Seafire. The Corsair was welcomed as a much more robust and versatile alternative.
In Royal Navy service, many Corsairs had their outer wings clipped to assist with carrier storage as well as benefitting its low-altitude performance Despite the clipped wings and the shorter decks of British carriers, RN aviators found landing accidents less of a problem than they had been to USN aviators due to the curved approach used. RN Corsairs saw widespread service with the British Pacific Fleet from late 1944 until the end of the war, some six carrier-based squadrons flying intensive ground attack/interdiction operations and also claiming 47.5 aircraft shot down.
The Royal Navy received 95 Corsair Mk Is and 510 Mk IIs, these being equivalent to the F4U-1 and -1A. Goodyear-built aircraft were known as Mk IIIs (equivalent to FG-1D), and Brewster-built aircraft as Mk IVs (equivalent to F3A-1D). British Corsairs had their wing tips clipped, 20 cm being removed at the tips, to allow storage of the F4U on the lower-overhead British carriers. The Royal Navy was the first to clear the F4U for carrier operations. It proved the Corsair Mk II could be operated with reasonable success even from escort carriers. It was not without problems, one being excessive wear of the arrester wires due to the weight of the Corsair and the understandable tendency of the pilots to stay well above the stalling speed.
Fleet Air Arm units were created and equipped in the US, at Quonset Point or Brunswick and then shipped to war theaters aboard escort carriers. The first FAA Corsair unit was No. 1830, created on the first of June 1943, and soon operating from HMS Illustrious. At the end of the war, 19 FAA squadrons were operating with the Corsair. British Corsairs operated both in Europe and in the Pacific. The first, and also most important, European operations were the series of attacks in April, July and August 1944 on the German battleship Tirpitz, for which Corsairs from HMS Victorious and HMS Formidable provided fighter cover. It appears the Corsairs did not encounter aerial opposition on these raids.
FAA Corsairs originally fought in a camouflage scheme with a Dark Slate Grey/Extra Dark Sea Grey disruptive pattern on top and Sky undersides, but were later painted overall dark blue. Those operating in the Pacific theater acquired a specialized British insignia - a modified blue-white roundel with white "bars" to make it look more like a U.S. than a Japanese Hinomaru insignia to prevent friendly-fire incidents. A total of 2,012 Corsairs were supplied to the United Kingdom.
In the Pacific, FAA Corsairs began to operate in April 1944, participating in an attack on Sabang, and later in the attack on oil refineries at Palembang. In July and August 1945, Corsair squadrons Nos. 1834, 1836, 1841, and 1842 took part in a series of strikes on the Japanese mainland, near Tokyo. They operated from the carriers HMS Victorious and Formidable.
At least one Corsair was captured by the Germans, this was Corsair JT404 from No. 1841 squadron (HMS Formidable). Wing Leader Lt Cdr RS Baker-Falkner made an emergency landing on 18 July 1944 in a field at Sorvag, near Bodø, Norway. The Corsair was captured intact and it is not known if it was taken to Germany.
On 9 August 1945, days before the end of the war, FAA Corsairs from Formidable were attacking Shiogama harbor on the northeast coast of Japan. Royal Canadian Navy pilot, Lieutenant Robert Hampton Gray, was hit by flak but pressed home his attack on a Japanese destroyer, sinking it with a 450 kilogram (1,000 pound) bomb but crashing into the sea. He was posthumously awarded Canada's last Victoria Cross, becoming the second fighter pilot of the war to earn a VC as well as the final Canadian casualty of the Second World War.
Royal New Zealand Air Force
Equipped with obsolescent Curtiss P-40s, RNZAF squadrons in the South Pacific performed impressively compared to the American units they operated alongside, in particular in the air-to-air role. The American government accordingly decided to give New Zealand early access to the Corsair, especially as it was not initially being used from carriers. Some 424 Corsairs equipped 13 RNZAF squadrons, including No. 14 Squadron RNZAF and No. 15 Squadron RNZAF, replacing SBD Dauntless as well as P-40s.
In late 1944, the F4U equipped all twelve Pacific-based fighter units of the RNZAF The first squadrons to use the Corsair were Nos 20 and 21 Squadrons on Espiritu Santo island, operational in May 1944. In the RNZAF Corsair units, only the pilots and a small staff belonged to the squadron; aircraft and maintenance crew were grouped in a pool.
By the time the Corsairs arrived, there were virtually no Japanese aircraft left in New Zealand's allocated sectors of the Southern Pacific, and despite the RNZAF Squadrons extending their operations to more northern islands, they were primarily used for close support of American, Australian and New Zealander soldiers fighting the Japanese. New Zealander pilots were aware of the Corsair's poor forward view and tendency to ground loop, but found these drawbacks could be solved by pilot training in curved approaches before use from rough forward airbases.
The RNZAF Corsairs mainly flew close-support missions, and as a consequence did not claim a single enemy aircraft shot down. At the end of 1945, all Corsair squadrons but one (No. 14) were disbanded. That last squadron was based in Japan, until the Corsair was retired from service in 1947.
No. 14 Squadron took its Corsairs to Japan as part of the British Commonwealth Occupation Force. Only one airworthy example of the 424 aircraft procured survives: NZ5648/ZK-COR, owned by the Old Stick and Rudder Company at Masterton, NZ. One other mostly complete aircraft and the remains of two others were known to be held by a private collector at Ardmore, NZ, in 1996. Their current whereabouts are unknown.
A total of 94 F4U-7s were built for the French Navy in 1952, with the last of the batch, the final Corsair built, rolled out on December 24, 1952. The F4U-7s were actually purchased by the U.S. Navy and passed on to the Aeronavale through the U.S. Military Assistance Program (MAP). The French used their F4U-7s during the end of the First Indochina War in the 1950s, where they were supplemented by at least 25 ex-USMC AU-1s passed on to the French in 1954, after the end of the Korean War.
French Corsairs also performed strikes in the Algerian War in 1955 and 1956 and assisted in the Anglo-French-Israeli seizure of the Suez Canal in October 1956, codenamed Operation Musketeer. The Corsairs were painted with yellow and black recognition stripes for this operation. In 1960, some French Corsairs were rigged to carry four SS-11 wire-guided missiles. This was a more or less experimental fit and it is hard to believe it worked well, since it required a pilot to "fly" the missile after launch with a joystick while keeping track of a flare on its tail – an exercise that could be very tricky in a single-seat aircraft under combat conditions. All French Corsairs were out of service by 1964, with some surviving for museum display or as civilian warbirds.
The "Football War"
Corsairs flew their final combat missions during the 1969 "Football War" between Honduras and El Salvador. The conflict was famously triggered, though not really caused, by a disagreement over a football (soccer) match. Both sides claimed various numbers of kills, and each side disputed the claims of the other.
The Corsair entered service in 1942. Although designed as a carrier fighter, initial operation from carrier decks proved to be troublesome. Its low-speed handling was tricky due to the port wing stalling before the starboard wing. This factor, together with poor visibility over the long nose (leading to one of its nicknames, "The Hose Nose"), made landing a Corsair on a carrier a difficult task. For these reasons, most Corsairs initially went to Marine Corps squadrons who operated off land-based runways, with some early Goodyear built examples (designated FG-1A) being built with fixed, non-folding wings. The USMC aviators welcomed the Corsair with open arms as its performance was far superior to the contemporary Brewster Buffalo and Grumman F4F-3 and -4 Wildcat.
Moreover, the Corsair was able to outperform the primary Japanese fighter, the Mitsubishi A6M "Zero". While the Zero could out-turn the F4U at low speed, the Corsair was faster and could out-climb and out-dive the A6M. Tactics developed early in the war, such as the Thach Weave, took advantage of the Corsair's strengths.
This performance advantage, combined with the ability to take severe punishment, meant a pilot could place an enemy aircraft in the killing zone from the F4U's six .50 (12.7 mm) Browning machine guns and keep him there long enough to inflict major damage. The 2,300 rounds carried by the Corsair gave over one full minute of fire from each gun, which, fired in three to six-second bursts, made the F4U a devastating weapon against aircraft, ground targets, and even ships.
Beginning in 1943, the Fleet Air Arm (FAA) also received Corsairs and flew them successfully from Royal Navy carriers in combat with the British Pacific Fleet and in Norway. These were clipped-wing Corsairs, the wingtips shortened eight inches (20 cm) to clear the lower overhead height of RN carriers. FAA also developed a curving landing approach to overcome the F4U's deficiencies.
Corsairs served with the U.S. Navy, U.S. Marines, Fleet Air Arm, and the Royal New Zealand Air Force, as well the French Aeronavale and other services postwar. It quickly became the most capable carrier-based fighter-bomber of World War II. Demand for the aircraft soon overwhelmed Vought's manufacturing capability, resulting in production by Goodyear (as the FG-1) and Brewster (as the F3A-1). From the first prototype delivery to the U.S. Navy in 1940, to final delivery in 1953 to the French, 12,571 F4U Corsairs were manufactured by Vought,in 16 separate models.
Infantrymen nicknamed the Corsair "The Sweetheart of the Marianas" and "The Angel of Okinawa" for its roles in these campaigns. Among Navy and Marine aviators, however, the aircraft was nicknamed "Ensign Eliminator" and "Bent-Wing Eliminator" because it required many more hours of flight training to master than other Navy carrier-borne aircraft. It was also called simply "U-bird" or "Bent Wing Bird". The Japanese allegedly nicknamed it "Whistling Death", for the noise made by airflow through the wing root-mounted oil cooler air intakes.
The Corsair has been named the official aircraft of Connecticut, due to its connection with Sikorsky Aircraft, in legislation sponsored by state senator George "Doc" Gunther; Gunther had also organized a Corsair Celebration and Symposium at Sikorsky Memorial Airport in Stratford, Connecticut, on Memorial Day, 29 May 2006.