Tag Archives: Test Pilot

25 May 1953

George S. Welch with North American YF-100A 52-5754. (North American Aviation, Inc.)

25 May 1953: North American Aviation Chief Test Pilot George S. Welch took the YF-100A Super Sabre, U.S. Air Force serial number 52-5754, for its first flight at Edwards Air Force Base. The airplane reached Mach 1.03.

Development of the Super Sabre began with an effort to increase the speed of the F-86D and F-86E Sabre fighters. The wings had more sweep and the airfoil sections were thinner. A much more powerful engine would be needed to achieve supersonic speed in level flight. As design work on the “Sabre 45” proceeded, the airplane evolved to a completely new design. Initially designated XF-100, continued refinements resulted in the first two aircraft being redesignated YF-100A.

North American Aviation Chief Test Pilot George S. Welch in the cockpit of the YF-100A, 52-5754, at Los Angeles International Airport. (North American Aviation, Inc.)
North American Aviation Chief Test Pilot George S. Welch in the cockpit of YF-100A 52-5754 at Los Angeles International Airport. (North American Aviation, Inc.)

The two YF-100As, 52-5754 and 52-5755, were 47 feet, 11¼ inches (14.611 meters) long with a wingspan of 36 feet, 7 inches (11.151 meters) and height of 16 feet, 3 inches (4.953 meters). The wings were swept to 45° at 25% chord, and had 0° angle of incidence and 0° dihedral. The ailerons were placed inboard on the wings to eliminate their twisting effects at high speed. The airplane had no flaps. The pre-production prototypes weighed 18,135 pounds (8,226 kilograms) empty, and had a gross weight of 24,789 pounds (11,244 kilograms).

The new air superiority fighter was powered by a Pratt & Whitney Turbo Wasp J57-P-7 engine. The J57 was a two-spool axial-flow turbojet which had a 16-stage compressor section (9 low- and 7 high-pressure stages) and a 3-stage turbine (2 high- and 1 low-pressure stages). The J57-P-7 had a Maximum Continuous Power rating of 8,000 pounds of thrust (35.586 kilonewtons) at 5,875 r.p.m., N1, and 9550 r.p.m., N2. The engine’s Military Power rating was 9,700 pounds thrust (43.148 kilonewtons) at 6,275 r.p.m./9,900 r.p.m., for 30 minutes; and 14,800 pounds thrust (65.834 kilonewtons) at 6,275 r.p.m./9,900 r.p.m. with afterburner, limited to five minutes. The engine was 20 feet, 9.7 inches (6.342 meters) long, 3 feet, 3.9 inches (1.014 meters) in diameter, and weighed 5,075 pounds (2,303 kilograms). Later production aircraft used a J57-P-39 engine, which had the same ratings.

Cutaway illustration ofa North American Aviation F-100A Super Sabre. (Boeing)
Cutaway illustration of a North American Aviation F-100A Super Sabre. (Boeing)
North American Aviation YF-100 Super Sabre 52-5754. (U.S. Air Force)
North American Aviation YF-100 Super Sabre 52-5754, 19 May 1953. (North American Aviation, Inc.)
The prototype North American Aviation YF-100A Super Sabre, 52-5754, with the North American F-100 team. Chief Test Pilot George S. Welch is in the center of the front row, seated. (North American Aviation, Inc.)

The YF-100A had a maximum speed of 660 miles per hour (1,062 kilometers per hour) at 43,350 feet (13,213 meters). The service ceiling was 52,600 feet (16,033 meters). Range with internal fuel was 422 miles (679 kilometers).

During testing, 52-5754 reached Mach 1.44 in a dive. On 29 October 1953, Colonel Frank K. Everest set a world speed record of 1,215.298 kilometers per hour (755.151 miles per hour) with 754.¹

In service with the United States Air Force, the Super Sabre’s mission changed from air superiority fighter to fighter bomber. It was used extensively during the Vietnam War. North American Aviation, Inc., built 2,294 single and tandem-seat Super Sabres between 1954 and 1959.

North American Aviation YF-100A Super Sabre 52-5754. (U.S. Air Force)
North American Aviation YF-100A Super Sabre 52-5754 over Edwards Air Force Base, California, 25 May 1953. (North American Aviation, Inc.)
North American Aviation YF-100A Super Sabre 52-5754 lands on the dry lake at Edwards Air Force Base, California. (North American Aviation, Inc.)

George Welch was born George Lewis Schwartz, in Wilmington, Delaware, 10 May 1918. His parents changed his surname to Welch, his mother’s maiden name, so that he would not be effected by the anti-German prejudice that was widespread in America following World War I. He studied mechanical engineering at Purdue, and enlisted in the Army Air Corps in 1939.

North American Aviation YF-100A Super Sabre 52-5754 banks away from a chase plane during a flight test. (U.S. Air Force)

George S. Welch is best remembered as one of the heroes of Pearl Harbor. He was one of only two fighter pilots to get airborne during the Japanese surprise attack on Hawaii, 7 December 1941. Flying a Curtiss P-40B Warhawk, he shot down three Aichi D3A “Val” dive bombers and one Mitsubishi A6M2 Zero fighter. For this action, Lieutenant General H.H. “Hap” Arnold recommended the Medal of Honor, but because Lieutenant Welch had taken off without orders, an officer in his chain of command refused to endorse the nomination. He received the Distinguished Service Cross. During the War, Welch flew the Bell P-39 Airacobra and Lockheed P-38 Lightning on 348 combat missions. He had 16 confirmed aerial victories over Japanese airplanes and rose to the rank of Major.

Suffering from malaria, George Welch was out of combat, and when North American Aviation approached him to test the new P-51H Mustang, General Arnold authorized his resignation. Welch test flew the P-51, FJ-1 Fury, F-86 Sabre and F-100 Super Sabre. He was killed 12 October 1954 when his F-100A Super Sabre came apart in a 7 G pull up from a Mach 1.5 dive.

North American Aviation pre-production prototype YF-100A Super Sabre 52-5754 with drag chute deployed on landing at Edwards Air Force Base, California. (U.S. Air Force)
North American Aviation pre-production prototype YF-100A Super Sabre 52-5754 with drag chute deployed on landing at Edwards Air Force Base, California. The extended pitot boom is used to calibrate instruments early in the flight test program. (U.S. Air Force)
North American Aviation YF-100 Super Sabre 52-5754 with external fuel tanks, parked on the dry lake at Edwards Air Force Base, California. (U.S. Air Force)

¹ FAI Record File Number 8868

© 2018, Bryan R. Swopes

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20 May 1941

NAA test pilot Robert C. Chilton stand on the wing of P-51B-10-NA 42-106435. (North American Aviation, Inc.)
North American Aviation test pilot Robert C. Chilton standing on the wing of P-51B-10-NA Mustang 42-106435. (North American Aviation, Inc.)

20 May 1941: North American Aviation, Inc., test pilot Robert Creed Chilton took the first XP-51 for its maiden flight at Mines Field, Los Angeles, California. The XP-51 was the fourth production Mustang Mk.I built for the Royal Air Force, (North American serial number 73-3101) and assigned registration number AG348.

The Mustang was reassigned to the U.S. Army Air Force, designated as XP-51, serial number 41-038, and sent to Wright Field, Dayton, Ohio, for evaluation.

North American Aviation Mustang Mk.I AG348 at Mines Field, California, 1941. North American Aviation, Inc., photograph 73-0-9. (Ray Wagner Collection/SDASM)
North American Aviation Mustang Mk.I AG348, Mines Field, California, 1941. North American Aviation, Inc., photograph 73-0-10. (Ray Wagner Collection/SDASM)
North American Aviation Mustang Mk.I AG348 at Mines Field, California, 1941. North American Aviation, Inc., photograph. (Ray Wagner Collection/SDASM)

Later, the XP-51 was extensively tested by the National Advisory Committee for Aeronautics (N.A.C.A.) at the Langley Memorial Aeronautical Laboratory, Langley Field, Hampton, Virginia.

Today, the restored XP-51 is in the collection of the E.A.A. AirVenture Museum at Oshkosh, Wisconsin.

North American Aviation XP-51 41-038 at the NACA Langley Memorial Aeronautical Laboratory. (NASA LMAL 27030)
North American Aviation XP-51 41-038 at the NACA Langley Memorial Aeronautical Laboratory. (NASA)

The Mustang Mk.I (NAA Model NA-73) was a single-place, single engine fighter primarily of metal construction with fabric control surfaces. It was 32 feet, 3 inches (9.830 meters) long with a wingspan of 37 feet, 5/16-inches (11.373 meters) and height of 12 feet, 2½ inches (3.721 meters). The airplane’s empty weight was 6,280 pounds (2,849 kilograms) and loaded weight was 8,400 pounds (3,810 kilograms).

North American Aviation XP-51 41-039 at NACA Langley. (NASA)
North American Aviation XP-51 41-039 at NACA Langley. Note the increased length of the carburetor intake. (NASA)

The Mustang was powered by a liquid-cooled, supercharged, 1,710.597-cubic-inch-displacement (28.032 liter) Allison Engineering Company V-1710-F3R (V-1710-39) single overhead cam (SOHC) 60° V-12 engine with a compression ratio of 6.65:1. The -F3R had a Normal Power rating of 880 horsepower at 2,600 r.p.m., at Sea Level, and 1,000 horsepower at 2,600 r.p.m. at 11,000 feet (3,353 meters). It had a Takeoff and Military Power rating of 1,150 horsepower at 3,000 r.p.m., to 11,800 feet (3,597 meters). The engine turned a 10 foot, 9 inch (3.277 meter) diameter three-bladed Curtiss Electric constant-speed propeller through a 2.00:1 gear reduction. The V-1710-F3R was 7 feet, 4.38 inches (2.245 meters) long, 3 feet, 0.54 inches (0.928 meters) high, and 2 feet, 5.29 (0.744 meters) wide. It weighed 1,310 pounds (594 kilograms).

The Mustang Mk.I had a maximum speed of 382 miles per hour (615 kilometers per hour) at 13,700 feet (4,176 meters), the Allison’s critical altitude, and cruise speed of 300 miles per hour (483 kilometers per hour). The service ceiling was 30,800 feet (9,388 meters) and range was 750 miles (1,207 kilometers).

North American Aviation XP-51 41-038 at NACA Langley Memorial Aeronautical Laboratory, right profile. (NASA LAML)
North American Aviation XP-51 41-038 at NACA Langley Memorial Aeronautical Laboratory, right profile. (NASA)

The Mustang Mk.I was armed with four air-cooled Browning .303 Mk.II aircraft machine guns, two in each wing, and four Browning AN-M2 .50-caliber machine guns, with one in each wing and two mounted in the nose under the engine.

North American Aviation XP-51 41-038 at NACA Langley Memorial Aeronautical Laboroatory. (NASA LAML 27045)
North American Aviation XP-51 41-038 at NACA Langley Memorial Aeronautical Laboratory, right three-quarter view. (NASA)

The Mk.I was 30 m.p.h. faster than its contemporary, the Curtiss P-40 Warhawk, though both used the same engine. Below 15,000 feet, the Mustang was also 30–35 m.p.h faster than a Supermarine Spitfire, which had a more powerful Roll-Royce Merlin V-12.

The XP-51 would be developed into the legendary P-51 Mustang. In production from 1941 to 1945, a total of 16,766 Mustangs of all variants were built.

North American Aviation XP-51 41-038 at NACA Langley Memorial Aeronautical Laboratory, rear view. (NASA LMAL 27033)
North American Aviation XP-51 41-038 at NACA Langley Memorial Aeronautical Laboratory, rear view. (NASA)

Robert Creed Chilton was born 6 February 1912 at Eugene, Oregon, the third of five children of Leo Wesley Chilton, a physician, and Edith Gertrude Gray. He attended Boise High School in Idaho, graduating in 1931. Chilton participated in football, track and basketball, and also competed in the state music contest. After high school, Chilton attended the University of Oregon where he was a member of the Sigma Chi fraternity (ΣΧ). He was also a member of the Reserve Officers Training Corps (ROTC).

Bob Chilton enlisted as an Aviation Cadet in the U.S. Army Air Corps, 25 June 1937. He was trained as a fighter pilot at Randolph Field and Kelly Field in Texas, and was commissioned as a Second Lieutenant in 1938. Lieutenant Chilton was assigned to fly the Curtiss P-36 Hawk with the 79th Pursuit Squadron, 20th Pursuit Group, at Barksdale Field, Louisiana. Because of a medical condition, he was released from active duty, 1 April 1939.

At some time prior to 1940, Bob Chilton, married his first wife, Catherine. They lived in Santa Maria, California, where he worked as a pilot at the local airport.

In January 1941, Chilton went to work as a production test pilot for North American Aviation, Inc., Inglewood, California. After just a few months, he was assigned to the NA-73X.

Chilton married his second wife, Betty W. Shoemaker, 15 November 1951.

On 10 April 1952, Bob Chilton returned to active duty with the U.S. Air Force, with the rank of lieutenant colonel. He served as Chief of the Republic F-84 and F-105 Weapons System Project Office, Air Material Command, at Wright-Patterson Air Force Base, Dayton, Ohio, until 9 March 1957.

From 1958, Chilton was a vice president for Horkey-Moore Associates, an engineering research and development company in Torrance, California, founded by former North American aerodynamacist Edward J. Horkey. In 1961, he followed Horkey to the Space Equipment Corporation, parent company of Thompson Industries and Kerr Products, also located in Torrance. Chilton served as corporate secretary and contracts administrator.

Chilton married his third wife, Wilhelmina E. Redding (Billie E. Johnson) at Los Angeles, 26 July 1964. They divorced in 1972.

In 1965, Bob Chilton returned to North American Aviation as a flight test program manager. He retired in 1977.

Robert Creed Chilton died at Eugene, Oregon, 31 December 1994, at the age of 82 years.

North American Aviation XP-51 at Wright Field. (Charles M. Daniels Collection, San Diego Air & Space Museum Archives, Catalog #: 15_002838)

© 2018, Bryan R. Swopes

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14 May 2005

Didier Delsalle approches the summit of Mount Everest. (Eurocopter)
Didier Delsalle approaches the summit of Mount Everest. (Eurocopter)

14 May 2005: Test pilot Didier Delsalle landed a Eurocopter AS 350 B3 Ecureuil, c/n 3934, registration F-WQEX, at the summit of Mount Everest, the highest point on Earth, at 8,848 meters (29,029 feet).

The Fédération Aéronautique Internationale required that the helicopter remain on the summit for at least two 2 minutes for the landing to be considered official. Delsalle actually landed on the summit twice, staying four minutes each time. The flight set two world records for the highest take-off. ¹

These records broke Delsalle’s previous records for highest take-off, 7,927 meters (26,007 feet), set just two days earlier. ²

Mount Everest, looking north. (Wikipedia)

During flight tests to evaluate the practicality of the Everest flight, on 14 April 2005, Delsalle and the AS 350 set three time to climb world records over Istres, France. The Écueriel climbed to a height of 3,000 meters (9,843 feet) in 2 minutes, 21 seconds; 6,000 meters (19,685 feet) in 5 minutes, 6 seconds; and 9,000 meters (29,528 feet) in 9 minutes, 26 seconds. ³

Delsalle also rescued two Japanese climbers at 16,000 feet (4,877 meters).

Didier DelSalle with F-WQEX, 2005
Didier DelSalle with F-WQEX, at Lukla, Nepal, 2005. Elevation 2,866 meters (9,403 feet). (Magazine Aviation)

Didier Delsalle was born 6 May 1957, at Aix-en-Provence, France. He joined the Armée de l’Air (French Air Force) in 1979, and was trained as fighter pilot. In 1981 he transitioned to helicopters and was assigned to search-and-rescue operations. After twelve years military service, Delsalle became an instructor at École du personnel navigant d’essais et de réception, the French test pilot school at Istres, France. He then became the chief test pilot for light helicopters for Eurocopter, and later for the NH90 medium helicopter.

Delsalle holds seven FAI world records, five of which remain current.

FAI representatve (left) presents a World Record certificate to Eurocopter test pilot Didier Delsalle while company CEO looks on. (Aviation International News)
Fédération Aéronautique Internationale (FAI) representative Jacques Escaffe (left) presents a World Record certificate to Eurocopter test pilot Didier Delsalle while company CEO Fabrice Brégier looks on. (Aviation International News)

The Eurocopter AS 350 Écureuil is a  6–7 place, single-engine light helicopter, operated by a crew of one or two pilots. (It is known as the A-Star in the United States.) Introduced by Aérospatiale in 1975, it remains in production today and is one of the most popular civil helicopters. The manufacturer is now known as Airbus Helicopters.

Eurocopter AS 350 B3 Écureuil F-WQEX. (Airbus Helicopters)

The AS 350 B3 is a high-performance variant, widely used in law enforcement. The overall length with rotors turning is 12.94 meters (42 feet, 5.4 inches). The fuselage is 10.93 meters (35 feet, 10.3 inches) long and the cabin is 1.87 meters (6 feet, 1.6 inches) wide. The helicopter’s overall height is 3.14 meters (10 feet, 3.6 inches).

In keeping with standard French practice, the Écureuil/A-Star’s main rotor system turns clockwise as seen from above. (The advancing blade is on the helicopter’s left side.) The fully-articulated the three-blade rotor has a diameter of 10.69 meters (35 feet, 0.9 inch). The normal operating range is 385–394 r.p.m. (320–430 r.p.m. in autorotation). A two-bladed tail rotor is mounted on the right side of the tail boom in a pusher configuration. It rotates clockwise, as seen from the helicopter’s left. (The advancing blade is below the axis of rotation.) Its diameter is 1.86 meters (6 feet, 1.2 inches.)

The AS 350 B3 has an empty weight of approximately 1,174 kilograms (2,588 pounds), depending on installed equipment, and maximum gross weight of 2,250 kilograms (4,961 pounds)

AS 350 B3 three-view illustration with dimensions. (Eurocopter)

The AS 350 B3 variant is powered by a single Turboméca Arriel 2B turboshaft engine. The Arriel 2B is a free turbine turboshaft engine which uses an electronic engine control system (EECU). The engine has a two-stage compressor section (single-stage low-pressure axial flow, single-stage high-pressure centrifugal flow); an annular combustion chamber; and two-stage turbine section (single-stage gas generator and single-stage power turbine). The compressor section turns 52,110 r.p.m. at 100% N1; The power turbine, N2, turns 39,095 r.p.m. at 100%. A gear reduction unit reduces the engine’s output shaft speed to 5,990 r.p.m.

The Arriel 2B produces 847 shaft horsepower, but is de-rated to the helicopter’s main transmission limit. Installed, the Arriel 2B is rated at 536 horsepower for cruise; 700 horsepower, Maximum Continuous Power; and 733 horsepower for take off (5 minute limit).

The Arriel 2B is 118.0 centimeters (3 feet, 10.46 inches) long, 50.0 cm (1 foot, 6.69 inches) wide, 62.0 cm (2 feet, 0.41 inches) high. It weighs 134 kilograms (295.4 pounds), dry. The Arriel series engines are now produced by Safran Helicopter Engines.

Eurocopter AS 350 B3 Écureuil c/n 3934, F-WQEX, at Mount Everest. (Eurocopter)

The AS 350 B3 has a cruise speed of 132 knots (152 miles per hour/245 kilometers per hour) and maximum speed of 155 knots (178 miles per hour/287 kilometers per hour). It carries over four hours of fuel and has a maximum range of 357 nautical miles (411 statute miles/662 kilometers). The maximum allowable altitude is 7,010 meters (23,000 feet).

AS 350 B3 c/n 3934 was originally registered F-WWPN, then F-WQEX, and was later registered as F-HMGM, in service with Hélimountains, Bourg-Saint-Maurice, France. As of 2014, F-WQEX is on display at the Musée de l’Aviation, Saint-Victoret, Provence-Alpes-Côte d’Azur, France.

Didier Delsalle with Eurocopter AS 350 B3 c/n 3934, F-WQEX. (André Bour/helicopassion.com)
Detail from The Henry Washburn Shaded Relief Map of Mount Everest. (Reddit)

¹ FAI Record File Number 11596: Highest take-off (Subclass E-1); FAI Record File Number 11596: Highest take-off (Subclass E-1c). 8,848 meters (29,029 feet).

² FAI Record File Number 11594: Highest take-off (Subclass E-1); FAI Record File Number 11595: Highest take-off (Subclass E-1c). 7,927 meters (26,007 feet).

³ FAI Record File Number 11323: 3,000 meters (9,843 feet), 2:21; FAI Record File Number 11325: 6,000 meters (19,685 feet), 5:06; and FAI Record File Number 11326: 9,000 meters (29,528 feet), 9:26.

© 2019, Bryan R. Swopes

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13 May 1949

English Electric A.1 VH799, first of four prototypes of the Canberra bomber. (BAE Systems)
English Electric A.1 VH799, first of four prototypes of the Canberra bomber. (BAE Systems)
Bee Beamont with an English Electric Canberra
Bee Beamont with an English Electric Canberra

Friday, 13 May 1949: At Warton Aerodrome, Lancashire, Chief Test Pilot Roland Prosper Beamont, C.B.E., D..S.O and Bar, D.F.C. and Bar, made the first test flight of the English Electric A.1 prototype, VN799, a very high altitude light bomber powered by two turbojet engines.

VN799 was the first of four prototypes. Three were equipped with Rolls-Royce

The newly completed airplane had been rolled out 2 May, and over the next several days underwent a series of static and taxi tests. The prototype was painted overall “plate blue.”

Rollout of English Electric A.1 VN799
Rollout of English Electric A.1 VN799 at Warton Aerodrome, 2 May 1949.
Airworthiness certificate
Ministry of Aircraft Production authorization for the Canberra’s first flight. The test pilot is specified by name. The serial numbers of the two Rolls-Royce jet engines are also listed.

“Bee” Beamont flew the prototype for approximately one-half hour. Other than a problem in yaw, which would be corrected with minor modifications to the vertical fin and rudder over the next several test flights, the aircraft performed very well. Months earlier, the bomber had been ordered into production “off the drawing board.”

English Electric A.1 VN799. Note the rounded vertical fin of this early configuration.
English Electric A.1 VN799. Note the rounded vertical fin of this early configuration.

British bombers have traditionally been named for cities. Canberra, capitol of Australia, was selected as the new airplane’s name in January 1950.

The English Electric B. Mk. I was a twin engine mid-wing bomber, operated by a pilot and navigator/bombardier. The Mk. I was 63 feet, 11 inches (19.482 meters) long, with a wing span of 66 feet, 3 inches (20.193 meters), and overall height of 15 feet, 6.9 inches. (4.747 meters). The wing used a symmetrical airfoil and had 2° angle of incidence. The inner wing had 2° dihedral, and the outer wing, 4° 21′. The total wing area was 960 square feet (89.2 square meters). The tailplane had a span of 27 feet, 4.9 inches (8.354 meters) with 1° angle of incidence and 10° dihedral. Total area of the stabilizer and elevators was 171.1 square feet (15.90 square meters).

Canberra VN799 at Farnborough Air Show, 1949. Note the squared-off vertical fin. (Ed Coates Collection)
Canberra VN799 at Farnborough Air Show, 1949. Note the squared-off vertical fin. (Ed Coates Collection)

VN799 was powered by two pre-production Rolls-Royce Avon R.A.2 engines. The Avon R.A.2 was a single-spool, axial flow turbojet with a 12-stage compressor section and single-stage turbine. It was rated at 6,000 pounds of thrust (26.69 kilonewtons). It weighed 2,400 pounds (1,089 kilograms). VN799 was the first British airplane built with an axial-flow turbojet engine.

VN799, flown by Flight Lieutenant Harry Maule with Scientific Officer I Mike Burgan, crashed at Sutton Heath, near RAF Woodbridge, 18 August 1953. The engines stopped due to fuel exhaustion while testing automatic landing systems. Maule and Burgan suffered minor injuries, but the airplane was destroyed. At the time of the crash, the prototype Canberra had flown a total of 1,540 hours, 40 minutes.

This Canberra T.4 WJ874 is painted as the first prototype B.1, VH799.(Ministry of Defense)
Canberra T.4 WJ874 is painted as the first prototype, VN799. (Ministry of Defense)

Interestingly, in October 1946, a 34-passenger civil transport variant of the Canberra was proposed, with an enlarged 10-foot-diameter fuselage.

The Canberra was produced in bomber, intruder, photo reconnaissance, electronic countermeasures and trainer variants by English Electric, Handley Page, A.V. Roe and Short and Harland. In the United States, a licensed version, the B-57A Canberra, was built by the Glenn L. Martin Company. The various versions were operated by nearly 20 nations. The Canberra was the United Kingdom’s only jet-powered bomber for four years. The last one in RAF service, a Canberra PR.9, made its final flight on 28 July 2008.

Colonel Charles E. ("Chuck") Yeager, USAF, commanding the 405th Fighter Wing, with crew chief TSGT Rodney Sirois, before a combat mission with a Martin B-57 Canberra during the Vietnam War. (Andrew Headland, Jr./Stars and Stripes)
Colonel Charles E. (“Chuck”) Yeager, USAF, commanding the 405th Fighter Wing, with crew chief TSGT Rodney Sirois, before a combat mission with a Martin B-57 Canberra bomber during the Vietnam War. (Andrew Headland, Jr./Stars and Stripes)

© 2019, Bryan R. Swopes

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6 May 1941

Republic XP-47B 40-3051 prototype in flight. (Republic Aircraft Corporation)

6 May 1941: Just eight months after a prototype for a new single-engine fighter was ordered by the U.S. Army Air Forces, test pilot Lowery Lawson Brabham took off from the Republic Aviation Corporation factory airfield at Farmingdale, New York, and flew the prototype XP-47B Thunderbolt, serial number 40-3051, to Mitchel Field, New York.

During the flight, oil which had collected in the exhaust duct began burning. There was so much smoke that Brabham considered bailing out. He stayed with the prototype, though, and when he arrived at Mitchel Field, he exclaimed, “I think we’ve hit the jackpot!”

Alexander Kartveli

The prototype was designed by Alexander Kartveli, a Georgian immigrant and former chief engineer for the Seversky Aircraft Corporation, which became the Republic Aviation Corporation in 1939.

Alexander Kartveli (née Kartvelishvili, ალექსანდრე ქართველი) was born in Tbilisi, in the Kutais Governorate of the Russian Empire, (what is now, Georgia). After World War I, during which he was wounded, Kartvelishvili was sent to study at the Paris Aviation Higher College of Engineering in France by the government of the Democratic Republic of Georgia. He graduated in 1922. Kartvelishvili did not return to his country, which had fallen to the Red Army in the Soviet-Georgian War. He worked for Blériot Aéronautique S.A. until 1928, when he was employed by the Fokker American Company (also known as Atlantic Aircraft, or Atlantic-Fokker) which was headquartered at Passaic, New Jersey, in the United States. In 1931, he became chief engineer for the Seversky Aircraft Company in Farmingdale.

Republic XP-47B Thunderbolt prototype 40-3051 at Farmingdale, New York, 1941. The pilot standing in front of the airplane gives a scale reference. (Republic Aviation Corporation)

The XP-47B was the largest single-engine fighter that had yet been built. The production P-47B was 34 feet, 10 inches (10.617 meters) long with a wingspan of 40 feet, 9-5/16 inches (12.429 meters), and height of 12 feet, 8 inches (3.861 meters).¹ The wing area was 300 square feet (27.9 square meters). At a gross weight of 12,086 pounds (5,482 kilograms), it was nearly twice as heavy as any of its contemporaries.

Republic XP-47B Thunderbolt 40-3051 at Wright Field, Dayton, Ohio.(Ray Wagner Collection, San Diego Air & Space Museum Archives )

The XP-47B was powered by an air-cooled, supercharged and turbocharged, 2,804.4-cubic-inch-displacement (45.956 liter) Pratt & Whitney R-2800-21 (Double Wasp TSB1-G) two-row, 18-cylinder radial with a compression ratio of 6.65:1 had a normal power rating of 1,625 horsepower at 2,550 r.p.m., to an altitude of 25,000 feet (7,620 meters), and a takeoff/military power rating of 2,000 horsepower at 2,700 r.p.m. at 25,000 feet (7,620 meters). The engine drove a 12-foot, 2 inch (3.708 meter) diameter, four-bladed Curtiss Electric constant-speed propeller through a 2:1 gear reduction. The R-2800-21 was 4 feet, 4.50 inches (1.340 meters) in diameter and 6 feet, 3.72 inches (1.923 meters) long. The engine weighed 2,265 pounds (1,027 kilograms). Approximately 80% of these engines were produced by the Ford Motor Company. It was also used as a commercial aircraft engine, with optional propeller gear reduction ratios.

A large General Electric turbosupercharger was mounted in the rear of the fuselage. Internal ducts carried exhaust gases from the engine to drive the turbocharger. This supercharged air was then carried forward through an intercooler and then on to the carburetor to supply the engine. The engine’s mechanical supercharger further pressurized the air-fuel charge.

Republic XP-47B 40-3051. The pilot enters the cockpit through a hinged canopy segment. (Ray Wagner Collection Catalog, San Diego Air and Space Museum)

During flight testing, the XP-47B Thunderbolt demonstrated speeds of 344.5 miles per hour (554.4 kilometers per hour) at 5,425 feet (1,654 meters), and 382 miles per hour (615 kilometers per hour) at 15,600 feet (4,745 meters). Its maximum speed was 412 miles per hour (663 kilometers per hour) at 25,800 feet (7,864 meters). The test pilot reported that the engine was unable to produce full power during these tests. It was determined that it had a cracked cylinder head, resulting in a loss of 2.5–4% of its maximum rated power. Also, the XP-47B was painted in camouflage, resulting in a slight loss of speed.

It could climb to 15,000 feet (4,572 meters) in just five minutes.

The Thunderbolt was armed with eight Browning AN-M2 .50-caliber machine guns, four in each wing, with 3,400 rounds of ammunition. It could also carry external fuel tanks, rockets and bombs. The structure of the P-47 could be described as “robust” and it was heavily armored. The amount of damage that the airplane could absorb and still return was remarkable.

 

Republic XP-47B Thunderbolt 40-3051, 4 May 1941. (U.S. Air Force)
Republic XP-47B Thunderbolt 40-3051, 4 May 1941. (Republic Aviation Corporation)

During a test flight, 4 August 1942, the XP-47B’s tail wheel was left down. The extreme heat of the turbocharger’s exhaust set fire to the tire, which then spread to the airplane’s fabric-covered control surfaces. Unable to control the airplane, test pilot Filmore L. Gilmer bailed out. The prototype Thunderbolt crashed into Long Island Sound and was destroyed.

The third production Republic P-47B Thunderbolt, 41-5897, at Langley Field, Virginia, 24 March 1942. The door-hinged canopy of the XP-47B has been replaced by a rearward-sliding canopy, requiring that the radio antenna mast be moved.(NASA)
A Republic P-47B Thunderbolt in the NACA Full Scale Tunnel, 31 July 1942. (NASA LMAL 29051)

A total of 15,683 Thunderbolts were built; more than any other Allied fighter type. In aerial combat, it had a kill-to-loss ratio of 4.6:1. The P-47, though, really made its name as a ground attack fighter, destroying aircraft, locomotives, rail cars, and tanks by the many thousands. It was one of the most successful aircraft of World War II.

¹ Data from Pilot’s Flight Operating Instructions, Technical Order No. 01-65BC-1, 20 January 1943

© 2018, Bryan R. Swopes

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