Tag Archives: Allison Division of General Motors

14 October 1938

The Curtiss-Wright XP-40 prototype on its first flight, 14 October 1938. Test pilot Ed Elliot is in the cockpit. (San Diego Air and Space Museum Archives)
The Curtiss-Wright XP-40 prototype on its first flight, 14 October 1938. Test pilot Ed Elliot is in the cockpit. (San Diego Air and Space Museum Archives)
Everett Edward Elliot (1919–1981). Photograph courtesy of Neil Corbett, Test Pilot and Engineers)
Everett Edward Elliot (Photograph courtesy of Neil Corbett, Test Pilot and Engineers)

14 October 1938: At Buffalo, New York, test pilot Everett Edward Elliot made the first flight in the new Curtiss-Wright Corporation’s Model 75P, a prototype for a single-engine pursuit plane which had been designated XP-40 by the U.S. Army Air Corps.

Curtiss-Wright’s Chief Engineer, Donovan Berlin, had taken the tenth production P-36A Hawk, Air Corps serial number 38-10, and had its air-cooled radial engine replaced with a Harold Caminez-designed, liquid-cooled, supercharged, 1,710.597-cubic-inch-displacement (28.032 liter) Allison Engineering Co. V-1710-C13 (V-1710-19). This was a single overhead cam (SOHC) 60° V-12 engine with four valves per cylinder and a compression ration of 6.65:1. It had a Normal Power rating of 910 horsepower at 2,600 r.p.m. at Sea Level, and 1,060 horsepower at 2,950 r.p.m. for Takeoff. At 10,000 feet (3,048 meters), the V-1710-19 had Maximum Continuous Power rating of 1,000 horsepower at 2,600 r.p.m., and Military Power rating of 1,150 horsepower at 2,950 r.p.m. The engine required 100/130-octane aviation gasoline. It drove a three-bladed Curtiss Electric constant-speed propeller through a 2:1 gear reduction. The V-1710-19 was 8 feet, 1.75 inches (2.483 meters) long, 3 feet, 4.75″ (1.035 meters) high and 2 feet, 4.94 inches (0.735 meters) wide. It weighed 1,320 pounds (599 kilograms).

At 1,829.39-cubic-inches (29.978 liters), the original Pratt & Whitney Twin Wasp S1C1-G (R-1830-17) 14-cylinder radial engine had greater displacement and produced 80 horsepower more for takeoff than the Allison V-12. The long, narrow V-12, though, allowed for a much more streamlined engine cowling for higher speed and greater efficiency.

Curtiss-Wright XP-40 prototype. (SDASM)
The Curtiss XP-40 prototype at Langley Field in the original configuration. (NASA)
The Curtiss XP-40 in the original configuration at Langley Field. (NASA)

In the early testing, the XP-40 was much slower than expected, reaching only 315 miles per hour (507 kilometers per hour). (The P-36A Hawk had a maximum speed of  313 miles per hour). Engineers experimented with different placement for the coolant radiator, oil coolers and the engine air intake. The Air Corps project officer, Lieutenant Benjamin Scovill Kelsey, had the prototype sent to the National Advisory Committee for Aeronautics (NACA) Research Center at Langley Field, Virginia, where the full-size airplane was placed inside a wind tunnel.

Lt. Benjamin Scovill Kelsey, U.S. Army Air Corps, in  the cockpit of a Curtiss P-36A Hawk at Wright Field, 1938. (U.S. Air Force)

Over a two-month period, NACA engineers made a number of improvements. The radiator was moved forward under the engine and the oil coolers utilized the same air scoop. The exhaust manifolds were improved as were the landing gear doors.

When they had finished, Lieutenant Kelsey flew the modified XP-40 back to Curtiss. Its speed had been increased to 354 miles per hour (570 kilometers per hour), a 12% improvement.

By December 1939 the airplane had been further improved and was capable of 366 miles per hour (589 kilometers per hour).

The Curtiss XP-40 prototype in a wind tunnel at Langley Field, 24 April 1939. (NASA)
Curtiss XP-40 in the NACA Full Scale Wind Tunnel at Langley Field, Virginia, April 1939. (NASA)
Curtiss XP-40 in the NACA Full Scale Wind Tunnel at Langley Field, Virginia, 24 April 1939. (NASA)

The Curtiss Hawk 75P, XP-40 38-10, was 31 feet, 1 inch (9.574 meters) long with a wingspan of 37 feet, 4 inches (11.354 meters) and overall height of 12 feet, 4 inches (3.734 meters). It had an empty weight of 5,417 pounds (2,457.1 kilograms) and maximum gross weight of 6,870 pounds (3,116.2 kilograms).

The prototype had a maximum speed of 342 miles per hour (550 kilometers per hour) at 12,200 feet (3,719 meters) with a gross weight of 6,260 pounds (2,839.5 kilograms). Its range was 460 miles (740 kilometers) flying at 299 miles per hour (481 kilometers per hour) with 100 gallons (378.5 liters) of fuel. With 159 gallons (601.9 liters) and with speed reduced to 200 miles per hour (322 kilometers per hour), the XP-40 had a maximum range of 1,180 miles (1,899 kilometers).

The prototype was armed with two air-cooled Browning AN-M2 .50-caliber machine guns mounted above the engine and synchronized to fire forward through the propeller arc.

The Air Corps placed an initial order for 524 P-40s. This was the largest single order for airplanes by the U.S. military up to that time. The first production model was the P-40 Warhawk, armed with two .50-caliber machine guns. There was only one P-40A variant which was a P-40 modified as a camera aircraft. The definitive pursuit model was the P-40B Warhawk, which retained the two .50-caliber guns of the P-40 and added two Browning M2 .30-caliber machine guns to each of the wings.

A Curtiss P-40B Warhawk, 79th Pursuit Squadron, 20th Pursuit Group, Hamilton Field, California, 1940. (U.S. Air Force)

The P-40B was best known as the airplane flown by the American Volunteer Group fighting for China against the Japanese. They were called the “Flying Tigers”. Between 1939 and 1945, Curtiss built 13,738 P-40s in many configurations. They flew in combat in every theater of operations during World War II.

A Curtiss Hawk 81-A3 (P-40B Warhawk) of the American Volunteer Group, Kunming, China, 1942. (U.S. Air Force)

© 2017, Bryan R. Swopes

Facebooktwittergoogle_plusredditpinterestlinkedinmailby feather

1 October 1947

North American Aviation test pilot George S. Welch, flying the first of three XP-86 prototypes, serial number 45-59597. (North American Aviation, Inc.)

1 October 1947: After three years development in which 801,386 engineering hours and 340,594 drafting hours had been expended, the first prototype North American Aviation XP-86 (company designation NA-140), serial number 45-59597, was ready for its first flight at Muroc Dry Lake in the high desert north of Los Angeles, California.

Completed at North American’s Inglewood plant on 8 August 1947, it was trucked to Muroc in mid-September. It was reassembled, everything was checked out, and after a few taxi tests, company test pilot George S. Welch took off for a initial familiarization flight. Chief Test Pilot Bob Chilton flew chase in an XP-82 Twin Mustang with a company photographer on board. The duration of the first flight was 1 hour, 18 minutes.

Recently completed, the first prototype XP-86, 45-59597, waits inside the North American Aviation plant at Inglewood, California, 14 August 1947. (North American Aviation, Inc.)

During this first flight, George Welch climbed to 35,000 feet (10,668 meters):

“In a little more than ten minutes he had reached 35,000 feet. Leveling out, the test pilot smiled as he watched the indicated airspeed accelerate to 320 knots. He estimated that should be 0.90 Mach number. . . Rolling into a 40 degree dive, he turned west. . . The airspeed indicator seemed to be stuck at about 350 knots. The Sabre was behaving just fine. Then at 29,000 feet, there was a little wing roll. Correcting the roll, George pushed into a steeper dive. The airspeed indicator suddenly jumped to 410 knots and continued to rise. At 25,000 feet, he pulled the Sabre into level flight and reduced power. The wing rocked again and the airspeed jumped back to 390.”

Aces Wild: The Race for Mach 1, by Al Blackburn, Scholarly Resources Inc., Wilmington, Delaware, 1998, at Chapter 5, Pages 144–145.

George Welch was the first to report instrument readings that would be referred to as “Mach jump.” It has been argued that George Welch flew the XP-86 beyond Mach 1 during this flight, breaking the “sound barrier” two weeks before Chuck Yeager did with the Bell X-1 rocketplane. During flight testing, it was firmly established that the XP-86 could reach Mach 1.02–1.04 in a dive, so it is certainly possible that he did so on the Sabre’s first flight.

North American Aviation Model NA-140, the first XP-86 prototype, 45-59597, at Muroc AAF, 1947. (U.S. Air Force)
North American Aviation Model NA-140, the first XP-86 prototype, 45-59597, at Muroc AAF, 1947. (U.S. Air Force)

The XP-86 was unlike any airplane before it. It was the first airplane with a swept wing. After analyzing test data from the Messerschmitt Me 262, North American’s engineers designed a wing with a 35° degree sweep back to its leading edge. The wing tapered toward the tips, and its thickness also decreased from the root to the tip. In order to create a very strong but very thin wing, it was built with a two-layered aluminum skin, instead of ribs and spars, with each layer separated by “hat” sections. The wing sweep allowed high speed shock waves to form without stalling the entire wing. The wing also incorporated leading edge “slats” which were airfoil sections that automatically extended below 290 knots, smoothing the air flow over the wing’s upper surface and creating more lift at slow speeds. Above that speed, aerodynamic forces closed the slats, decreasing drag and allowing for higher speeds. Effectively, the wing could change its shape in flight.

Test pilot George S. Welch, wearing his distinctive orange helmet, in the cockpit of the prototype XP-86. This photograph was taken 14 October 1947. (U.S. Air Force)
This photograph of the XP-86 shows the 35° wing sweep. Test pilot George S. Welch, wearing his distinctive orange helmet, in the cockpit of the prototype XP-86. (North American Aviation, Inc.)

The XP-86 prototypes were 37 feet, 6½ inches (11.443 meters) long with a wingspan of 37 feet, 1–7/16 inches (11.314 meters) and overall height of 14 feet, 9 inches (4.496 meters). The empty weight was 9,730 pounds (4,413.5 kilograms), gross weight, 13,395 pounds (6,075.9 kilograms) and maximum takeoff weight was 16,438 pounds (7,456.2 kilograms).

The XP-86 was initially powered by a General Electric-designed, Chevrolet-built J35-C-3 turbojet which produced 4,000 pounds of thrust. This was soon changed to an Allison J35-A-5. Performance testing was conducted with the Allison engine installed. The J35 was a single-spool, axial-flow turbojet engine with an 11-stage compressor and single-stage turbine. The J35-A-5 was rated at 4,000 pounds of thrust (17.79 kilonewtons) at 7,700 r.p.m. (static thrust, Sea Level). The engine was 14 feet, 0.0 inches (4.267 meters) long, 3 feet, 4.0 inches (1.016 meters) in diameter and weighed 2,400 pounds (1,089 kilograms).

The three North American Aviation XP-86 prototypes. Front to back, 45-59598, 45-59597 and 45-59599. (National Archives and Records Administration)

The maximum speed of the XP-86 at Sea Level was 0.787 Mach (599 miles per hour, 964 kilometers per hour), 0.854 Mach (618 miles per hour, 995 kilometers per hour) at 14,000 feet (4,267 meters) and 575 miles per hour (925 kilometers per hour) at 35,000 feet (10,668 meters)—0.875 Mach.

The prototype fighter was able to take off at 125 miles per hour (201 kilometers per hour) in just 3,020 feet (920.5 meters) of runway. It could climb to 30,000 feet (9,144 meters) in 12.1 minutes and had a service ceiling of 41,300 feet (12,588 meters).

George S. Welch, North American Aviation test pilot, wearing his orange flight helmet. An F-86 Sabre is in the background. (San Diego Air and Space Museum Photo Archives)

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.

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 World War II, George 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 F-86-A-NA Sabre 47-630. (North American Aviation, Inc./Chicago Tribune)
North American Aviation F-86A-1-NA Sabre 47-630. (North American Aviation, Inc./Chicago Tribune)

After testing, the North American Aviation XP-86 was approved for production as the F-86A. It became operational in 1949. The first squadron to fly the F-86 held a naming contest and from 78 suggestions, the name “Sabre” was chosen. The F-86 Sabre was in production until 1955 at North American’s Inglewood, California and Cleveland, Ohio plants. It was also built under license by Canadair, Ltd., Sain-Laurent, Quebec, Canada; the Commonwealth Aircraft Corporation, Port Melbourne, Victoria, Australia; and Mitsubishi Heavy  Industries at Nagoya, Aichi Prefecture, Japan. A total of 9,860 Sabres were built. They served with the United States Air Force until 1970.

XP-86 45-59597 was expended in nuclear weapons tests, Operation Snapper Easy and Snapper Fox, at the Nevada Test Site, Frenchman’s Flat, Nevada, in May 1952. The second and third prototypes, 45-59598 and 45-59599, met similar fates.

© 2017, Bryan R. Swopes

Facebooktwittergoogle_plusredditpinterestlinkedinmailby feather

30 September 1982

H. Ross Perot, Jr. and Jay W. Coburn with Bell 206L-1 LongRanger II, N3911Z, after their 29-day around-the-world flight. (© Bettman/Corbis)

30 September 1982: H. Ross Perot, Jr. and Jay W. Coburn completed their around-the-world helicopter flight when they landed Spirit of Texas at their starting point at Dallas, Texas. They had flown the single-engine Bell 206L-1 LongRanger II, serial number 45658, civil registration N3911Z, more than 26,000 miles (41,843 kilometers) in 246.5 flight hours over 29 days, 3 hours and 8 minutes.

They had begun their journey 1 September 1982. Perot and Coburn traveled across twenty-six countries. They established a Fédération Aéronautique Internationale (FAI) record for helicopter speed around the world, eastbound, having averaged 56.97 kilometers per hour (35.399 miles per hour). (Class E-1d, FAI Record File Number 1254). They also established a series of point-to-point records while enroute, with the highest speed, an average of 179.39 kilometers per hour (111.47 miles per hour), taking place on 7 September 1982, while flying Spirit of Texas from London to Marseilles (FAI Record File Number 10018).

The Bell Helicopter Company Model 206L-1 LongRanger II is a 7-place light helicopter developed from the earlier 5-place Model 206B JetRanger series. It is designed to be flown by a single pilot in the right front seat, and is certified for Visual Flight Rules.

The 206L-1 is 42 feet, 8 inches (13.005 meters) long, overall, and the two-bladed main rotor is semi-rigid and under-slung, a common feature of Bell’s main rotor design. It has a diameter of 37 feet (11.278 meters) and turns counter-clockwise (seen from above) at 394 r.p.m. (100% NR). (The advancing blade is on the helicopter’s right side.) The rotor blade has a chord of 1 foot, 1.0 inches (0.330 meter) and 11° negative twist. The blade tips are swept.

The two-bladed tail rotor assembly is also semi-rigid and is positioned on the left side of the tail boom in a pusher configuration. It turns clockwise, as seen from the helicopter’s left. (The advancing blade is below the axis of rotation.) The tail rotor diameter is 5 feet, 6.0 inches (1.676 meters).

The LongRanger II is powered by an Allison 250-C28B turboshaft engine. This engine produces 500 shaft horsepower but is de-rated to 435 horsepower, the limit of the main transmission. The engine is mounted above the roof of the fuselage, to the rear of the main transmission. Output shafts lead forward to the transmission and the tail rotor drive shaft aft to the tail rotor 90° gear box. The transmission and rotor mast are mounted angled slightly forward and to the right. This assists in the helicopter’s lift off to a hover, helps to offset its translating tendency, and keeps the passenger cabin in a near-level attitude during cruise flight.

A vertical fin is attached at the aft end of the tail boom. The fin is offset 4° to the right to unload the tail rotor in cruise flight. Fixed horizontal stabilizers with an inverted asymmetric airfoil are attached to the tail boom. In cruise flight, these provide a downward force that keeps the passenger cabin in a near-level attitude. Vertical fins are attached to the outboard ends of the horizontal stabilizers and above the tailboom centerline. The fins are slightly offset to the left and counteract the helicopter’s Dutch roll tendency.

The helicopter has an empty weight of approximately 2,160 pounds (979 kilograms), depending on installed equipment, and the maximum gross weight is 4,050 pounds (1,836 kilograms).

The Model 206L LongRanger first flew in 1974 and the 206L-1 LongRanger II variant entered production in 1978. It was replaced several years later by the 206L-3. The LongRanger remains in production as the Model 206L-4.

Screen Shot 2015-09-30 at 09.44.55Perot had purchased the LongRanger II for $750,000, specifically for this flight. Modifications started immediately and over the next three weeks an additional 151-gallon fuel tank was added giving the helicopter approximately 8 hours’ endurance. “Pop-out floats”—inflatable pontoons that can be deployed for emergency landings on water—were installed. The helicopter also carried a life raft and other emergency equipment and supplies. Additional communication, navigation equipment and radar was installed.

Spirit of Texas aboard a container ship.
N3911Z aboard a container ship.

During the circumnavigation, the helicopter burned 56,000 pounds (25,400 kilograms) of jet fuel and made 56 fueling stops, including aboard a pre-positioned container ship in the North Pacific Ocean.

The helicopter was donated to the Smithsonian Institution and is on display at the Steven V. Udvar-Hazy Center of the National Air and Space Museum.

Bell 206L-1 LongRanger II s/n 45658, N3911Z, “Spirit of Texas,” on display at the Steven F. Udvar-Hazy Center of the Smithsonian Institution National Air and Space Museum. (NASM)

© 2016, Bryan R. Swopes

Facebooktwittergoogle_plusredditpinterestlinkedinmailby feather

18 September 1948

Lieutenant Ellis Dent Shannon, Air Corps, United States Army

18 September 1948: The first delta-winged aircraft took flight for the first time when Consolidated-Vultee Aircraft Corporation test pilot Ellis D. “Sam” Shannon lifted off from Muroc Dry Lake with the prototype delta-wing XF-92A, serial number 46-682. For the next  18 minutes he familiarized himself with the new aircraft type, before landing back on the lake bed.

The Convair XF-92 on Rogers Dry lake. (U.S. Air Force)
The Convair XF-92A on Muroc Dry Lake. (U.S. Air Force)

Later, with Captain Chuck Yeager flying, the XF-92A reached Mach 1.05. Yeager found that the airplane’s delta wing made it nearly impossible to stall, even with a 45° angle of attack. He was able to land the airplane at nearly 100 miles per hour slower than the designers had predicted.

The XF-92A was a difficult airplane to fly. NACA test pilot Scott Crossfield commented, “Nobody wanted to fly the XF-92. There was no lineup of pilots for the airplane. It was a miserable flying beast.” Scotty made 25 flights in the experimental delta-winged aircraft. On its last flight, 14 October 1953, the airplane’s nose gear collapsed after landing. The XF-92A was damaged and never flew again.

Convair XF-92A 46-682 on Muroc Dry Lake, 1948. (U.S. Air Force)
Convair XF-92A 46-682 on Muroc Dry Lake, 1948. (U.S. Air Force)

The XF-92A (Consolidated-Vultee Model 7-002) was a single-place, single-engine prototype fighter. The airplane was 42 feet, 6 inches (12.954 meters) long with a wingspan of 31 feet, 4 inches (9.550 meters) and overall height of 17 feet, 9 inches (5.410 meters). It had an empty weight of 9,078 pounds (4,118 kilograms) and gross weight of 14,608 pounds (6,626 kilograms).

The prototype was originally powered by It was powered by an Allison J33-A-21 centrifugal-flow turbojet engine with a single-stage compressor and single-stage turbine. It produced 4,250 pounds of thrust at 11,500 r.p.m. at Sea Level. This was later replaced by a more powerful J33-A-29 (7,500 pounds thrust).

The XF-92A touches down on Muroc Dry Lake, 1948. (San Diego Air and Space Museum Archives)
The XF-92A touches down on Muroc Dry Lake, 1948. (San Diego Air and Space Museum Archives)

The XF-92A had a maximum speed of 718 miles per hour (1,156 kilometers per hour) and a service ceiling of 50,750 feet (15,469 meters).

The XF-92A was not put into production. It did appear in several motion pictures, including “Toward The Unknown” (one of my favorites). It is in the collection of the National Museum of the United States Air Force. This was the first of several Convair delta-winged aircraft, including the F2Y Sea Dart, F-102A Delta Dart and F-106A Delta Dagger supersonic interceptors, and the B-58A Hustler four-engine Mach 2+ strategic bomber.

Consolidated-Vultee XF-92A 46-682 is displayed at the National Museum of the United States Air Force, Wright-Patterson Air Force Base, Ohio.

The flight test program of the XF-92A came to an ignonimous colclusion
The flight test program of the XF-92A came to an ignominious conclusion on 14 October 1953. (San Diego Air and Space Museum Archives)

Ellis Dent Shannon was born at Andalusia, Alabama, 7 February 1908. He was the third of five children of John William and Lucy Ellen Barnes Shannon.

He was commissioned as a second lieutenant the Alabama National Guard (Troop C, 55th Machine Gun Squadron, Cavalry) 21 May 1926. He transferred to the U.S. Army Air Corps in 1929. In 1930, he was stationed at Brooks Army Airfield, Texas.

In 1932 Shannon was employed was assigned as a flight instructor and an advisor to the government of China.

On 24 December 1932, Shannon married Miss Martha Elizabeth Reid at Shanghai, China. They had son, Ellis Reid Shannon, born at Shanghai, 24 August 1934, and a daughter, Ann N. Shannon, born at Baltimore, Maryland, in 1940.

Shannon and his family returned to the United States in 1935 aboard SS Bremen, arriving at New York.

He was employed by the Glenn L. Martin Co., at Baltimore, Maryland, in 1936 as a test and demonstration pilot. He travel throughout Latin America for the company, demonstrating the company’s aircraft. As a test pilot he flew the Martin Model 187 Baltimore, the B-26 Marauder, PBM Mariner and the Martin JRM Mars.

In February 1943, Shannon started working as a Chief of Flight Research for the Consolidated Aircraft Company at San Diego, California. While there, made the first flights of the Consolidated XB-24K, a variant of the Liberator bomber with a single vertical tail fin; the XR2Y-1, a prototype commercial airliner based on the B-24 Liberator bomber; the XB-46 jet-powered medium bomber; the XP5Y-1 Tradewind, a large flying boat powered by four-turboprop-engines; the Convair 340 Metropolitan airliner; and the XF2Y Sea Dart, a delta-winged seaplane powered by two turbojet engines. Shannon also participated in the flight test program of the YF-102A Delta Dart.

After retiring from Convair in 1956, Ellis and Martha Shannon remained in the San Diego area. Ellis Dent Shannon died at San Diego, California, 8 April 1982 at the age of 74 years.

Ellis Dent Shannon, Convair test pilot (Photograph courtesy of Neil Corbett, Test and Research Pilots, Flight Test Engineers)
Ellis Dent Shannon, Convair test pilot, circa 1953. (Photograph courtesy of Neil Corbett, Test and Research Pilots, Flight Test Engineers)

© 2017, Bryan R. Swopes

Facebooktwittergoogle_plusredditpinterestlinkedinmailby feather

1 September 1946

Alvin M. “Tex” Johnston with the Thompson Trophy and the Allegheny-Ludlum Trophy, 1946 National Air Races. (San Diego Air and Space Museum Archives)

1 September 1946: Just one year after World War II came to an end, the National Air Races returned to Cleveland, Ohio. Grandstands were set up at the site of the Fisher Body Aircraft Plant No. 2, where assemblies for B-25 and B-29 bombers had been produced.

The Thompson Trophy Race was one of the most popular events because it was in view of the crowds. Sponsored by Thompson Products Company (the predecessor of TRW), it was a ten-lap pylon race flown at low altitude around a 30-mile (48.3 kilometers) course. There were two divisions. The R Division was for airplanes with reciprocating engines, and the J Division was for turbojet powered airplanes.

The race course was laid out as a parallelogram, with two 10-mile (16.1 kilometer) sides, and two 5-mile (8.0 kilometer) sides. There were two 75° turns and two 105° turns.

In addition to the Thompson Trophy, the race winner would receive $20,000 in prize money (about $265,400 in 2017 dollars). There were additional $2,000 prizes for the leader of each lap. A pilot who set a speed record during the race would win the Allegheny-Ludlum Trophy and $2,000.

Entrants for the 1946 race included many well-known air racers, test pilots and combat pilots. They included Cook Cleland, a U.S. Navy dive bomber pilot and test pilot; Woodrow W. (“Woody”) Edmondson, an aerobatic pilot; Howard Clifton (“Tick”) Lilly, a test pilot for the National Advisory Committee for Aeronautics (NACA, predecessor of NASA); Alvin Melvin (“Tex”) Johnston, an experimental test pilot with the Bell Aircraft Corporation; Anthony W. (“Tony”) LeVier, Chief Engineering Test Pilot for the Lockheed Aircraft Corporation, and an experienced pylon racer; Earl Hill Ortman, test pilot for Douglas Aircraft Company, and also an experienced racer; Howard L. Pemberton; Bruce Raymond; Robert Swanson; Charles (“Chuck”) Tucker, who had flown P-40s with the “Flying Tigers” in China, and an Army Air Corps test pilot; George Schwarz Welch, the Army Air Corps hero of Pearl Harbor, and test pilot for North American Aviation, Inc.; and Sylvester Joseph (“Steve”) Wittman, an aircraft designer and air racer.

Before the war, the races used specially-constructed racing aircraft and production civil aircraft. Following the war, the expense of developing a purpose-built, competitive air racer was no longer feasible, so surplus military fighters were used.

Of the twelve airplanes competing in the 1946 Thompson Race, there was one Bell Aircraft Corporation P-39Q Airacobra; four Bell P-63 Kingcobras; one Goodyear Aircraft Corporation FG-1D Corsair (a licensed variant of the Vought-Sikorsky F4U Corsair); a Lockheed Aircraft Corporation P-38L Lightning; and five North American Aviation, Inc., P-51D Mustangs.

Bell Aircraft Corporation

Jack Woolams, Chief Test Pilot for Bell Aircraft Corporation, Experimental Test Pilot Tex Johnston and Bell’s Chief Engineer, Robert Morris Stanley, had determined that a properly prepared Bell P-39 Airacobra could outrun and outfly a North American Aviation P-51 Mustang in the Thompson race.

A Bell Aircraft mechanic was sent to inspect surplus P-39s in storage at Ponca City, Oklahoma. He selected two nearly-new P-39Q Airacobras, each with less than 50 hours flight time. Woolams and Johnston paid $3,000 for the two fighters and they were flown back to the Bell plant at Buffalo, New York.

Jack Woolams’ Cobra I was a P-39Q-10-BE, U.S. Army Air Corps serial number 42-20733. Tex Johnston’s Cobra II was also a P-39Q-10-BE, 42-20869 (Bell serial number 26E-324).

The Bell P-39 Airacobra was a single-engine, single-place low-wing monoplane with retractable tricycle landing gear. An Allison V-1710 V-12 engine was mounted behind the cockpit in an unusual mid-engine configuration, with a drive shaft passing under the cockpit floor and turning the propeller through a remotely-mounted 1.8:1 gear reduction unit. This allowed the fighter to be armed with a large 37 mm autocannon which fired through the propeller hub.

Bell P-39Q-20-BE Airacobra 44-3887 at the National Museum of the United States Air Force)

The P-39Q was the final production version of the Airacobra. It was 30 feet, 2 inches (9.195 meters) long with a wingspan of 34 feet, 0 inches (10.363 meters) overall height of 12 feet, 5 inches (3.785 meters). The P-39Q had an empty weight of 5,645 pounds (2,561 kilograms), and maximum gross of 8,300 pounds (3,765 kilograms).

Allison Division of General Motors

The production P-39Q was powered by a liquid-cooled, supercharged, 1,710.597-cubic-inch-displacement (28.032 liter) Allison Engineering Company V-1710-E19 (V-1710-85) single overhead camshaft (SOHC) 60° V-12 engine with four valves per cylinder and a compression ratio of 6.65:1. The V-1710-85 had a continuous power rating of 810 horsepower at 2,600 r.p.m. at Sea Level, and 1,000 horsepower at 2,600 r.p.m. at 14,000 feet (4,267 meters). The engine’s takeoff power rating was 1,200 horsepower at 3,000 r.p.m., and its military power rating was 1,125 horsepower at 3,000 r.p.m., at 14,600 feet (4,450 meters). 100/130 octane aviation gasoline was required. The Allison drove a three-bladed Aeroproducts Division A632S-C1 hydraulically-operated constant-speed propeller with a diameter of 11 feet, 7 inches (3.531 meters) through a 2.23:1 gear reduction. The V-1710-85 was 16 feet, 2.00 inches (4.928 meters) long, 3 feet, 1.56 inches (0.954 meters) high, and 2 feet, 5.28 inches (0.744 meters) wide. It weighed 1,435 pounds (651 kilograms).

Cutaway illustration showing the unusual mid-engine arrangement of the Bell P-39 Airacobra. (Allison Division of General Motors)

The Bell P39Q had a maximum speed of 385.0 mph (619.6 kilometers per hour) at 11,000 feet (3,353 meters). Its service ceiling was 34,900 feet (10,638 meters), absolute ceiling, 35,700 feet (10,881 meters), and its range was 1,075 miles (1,730 kilometers).

The P-39Q was armed with one Browning M4 37 mm autocannon with 30 rounds of explosive ammunition, and four Browning AN-M2 .50-caliber machine guns, with two in the nose with 200 rounds per gun, and one mounted under each wing in pods with 300 rounds per gun.

The Bell Aircraft Corporation built 9,558 P-39s. 4,905 of these were P-39Qs. 705 were the P-39Q-10-BE variant.

Jack Woolams (left) and Tex Johnston pose with their air racers, Cobra I and Cobra II, at the Bell Aircraft Corporation plant, August 1946. (airrace,com)

Bell Aircraft provided hangar space for the two Airacobras, and assigned an engineer and five mechanics to the project. Cobra I was painted red with black accents. It was issued Civil Aeronautics Administration experimental registration NX92847. Its race number, 75, was painted on the wings and fuselage. Cobra II was painted yellow with black trim, and registered NX92848. Its race number was 84.

Both airplanes were stripped of armament, armor and self-sealing fuel tanks. The landing gear was modified to reduce its retraction time from 22 seconds to just 4 seconds. The standard fabric-covered ailerons, rudder and elevators were covered with sheet aluminum. Adjustable trim tabs were deleted. Gyroscopic instruments were removed. The pitot tube was moved from the left wing tip and placed on a long boom projecting through the propeller hub. Thin, light-weight Goodyear fuel bladders were installed, not only reducing weight, but increasing the Airacobras’ fuel capacity by 10%. The roll-down side windows of the P-39 were replaced by fixed Plexiglas panels.

Bell P-39Q-10-BE NX92848, Cobra II, Tex Johnston’s Thompson Trophy Race winner. (San Diego Air and Space Museum Archives)

Engineers at Allison recommended that a modified Allison XV-1710-135 (E31) engine be used. The modified engines used an increased-diameter supercharger impeller and undersized pistons to reduce cylinder wall friction. Using 140-octane Mobil aviation gasoline, they produced 2,000 horsepower at 3,200 r.p.m. with 86 inches (291 kilopascals) of manifold pressure. The high power output required that the engine be provided with a continuous injection of a precisely-measured water and ethyl/methyl alcohol solution above 57 inches (193 kilopascals) of manifold pressure. An 85 gallon (322 liter) tank for the injection mixture was placed in the nose.

Tex Johnston’s Thompson Trophy-winning Bell P39Q Airacobra, “Cobra II.” (San Diego Air and Space Museum Archives)

The increased power of the modified XV-1710-135 required that the P-39’s standard three-bladed propeller be replaced by a four bladed unit from the P-63 Kingcobra. This was an Aeroproducts A624S constant-speed propeller with hollow steel blades. Its diameter was 11 feet, 0 inches (3.531 meters). The propeller gear reduction ratio remained the same, at 2.23:1, as did the remote gear box, at 1.8:1.

Allison V-1710-E19 (V-1710-85) with extension drive shaft and remote propeller drive gear unit. (Allison Division of General Motors)

The V-1710-E31 was longer, at 17 feet, 4.00 inches (5.283 meters), and heavier, than the E19 because of an outboard reduction gear box. It was 3 feet, 0.75 inches (0.933 meters) high, with the same 2 foot, 5.28 inch (0.744 meters) width. It weighed 1,500 pounds (680 kilograms).

Jack Woolams’ P-39 Cobra I leads a P-51D Mustang around a pylon turn during qualifying, August 1946. (LIFE Magazine via Jet Pilot Overseas)

When race qualifications were held, Tex Johnston was placed first with his yellow Cobra II. His average speed was 409.091 mph (658.368 kilometers per hour). George Welch was second with his P-51D, number 37. Jack Woolams and Cobra I were third.

Jack Valentine Woolams

Jack Valentine Woolams was killed on 30 August, two days before the race, when his Cobra I crashed into Lake Ontario while returning to the Bell plant for an engine change. The Airacobra’s windshield may have collapsed at over 400 miles per hour (644 kilometers per hour).

The race was held on Sunday, 1 September 1946. Tex Johnston, leading the field, took off and retracted his landing gear, climbing to 300 feet (91 meters). As he approached the first turn, he rolled Cobra II into a 4G turn (75.5° angle of bank) and dove to 60 feet (18 meters). As he made the turn, he was already pulling far ahead of the other racers.

George Welch dropped out when his Merlin engine began overheating. Tony LeVier’s P-38 Lightning, race number 3, held on to second place. By the ninth lap, Tex Johnston was passing the airplanes at the back of the field.

On the final turn, Johnston rolled into a 90° bank, and at only 50 feet (15 meters) above the ground, passed inside a Bell P-63 Kingcobra at 430 miles per hour (692 kilometers per hour) to win the race. His average speed for the ten laps was 373.908 mph (601.746 kilometers per hour).

After winning the 1946 Thompson Trophy Race, test pilot Tex Johnston kisses his wife, DeLores. (LIFE Magazine via Jet Pilot Overseas.)
Tex Johnston with the Thompson Trophy, 1946 National Air Races, Cleveland, Ohio. (LIFE Magazine)

Tony LeVier and his Lightning were in second place at 370.193 mph (595.768 kilometers per hour). Finishers 3, 4 and 5 were P-51D Mustangs. Number 6 was the lone FG-1D Corsair, followed by another P-51D. Proving that Woolams, Johnston and Stanley knew their airplane, the final three finishers were the three remaining P-63 Kingcobras.

An oil-streaked, race-winning Bell P-39Q Airacobra, NX92848, Tex Johnston’s Cobra II. The modified Allison engine’s undersized pistons allowed excessive blow-by. (San Diego Air and Space Museum Archives)

Cobra II competed in the 1947 Thompson Trophy Race. Flown by Bell Aircraft Corp. test pilot Gerald A. (“Jay”) Demming, and carrying the race number 11, it finished in third place behind two Goodyear F2G-1 Super Corsairs. Demming’s average speed was 367.625 miles per hour (591.635 kilometers per hour).

In the 1948 Thompson race, Cobra II, still carrying the number 11, was flown by Charles Brown. For this year, the race was twenty laps of a shorter, 15 mile (24.1 kilometer) course. Cobra II had qualified in first place with an average speed of 418.300 miles per hour (673.189 kilometers per hour). Brown led the race for 18 laps. His highest speed for a single lap was 413.907 miles per hour (666.119 kilometers per hour). He had to land, though, when the modified Allison engine began losing power. The race was won by a P-51D Mustang.

Bell P-39Q-10-BE Airacobra NX92849
Cobra II at the 1947 National Air Races, with race number 11. It was flown in the Thompson Trophy race by Bell test pilot Jay Demming, who placed third.

The history of Cobra II is elusive until it was purchased by Ed Maloney in 1960. It was sold to Michael D. Carroll in 1967. Carroll was the owner of Signal Trucking Co., and lived in Palos Verdes, California. The Airacobra was now registered N9824. Carroll had the airplane’s wings shortened by 4 feet per side (1.2 meters), and renamed it Cobra III.

On 10 August 1968, Carroll and Cobra III took of from Long Beach Airport (LGB), enroute to Orange County Airport (SNA), at nearby Santa Ana, California. At 11:15 a.m., the racer crashed at the Seal Beach Naval Weapons Station. Carroll bailed out, but his parachute did not open and he was killed. His body was located 125 feet (38 meters) from the wreckage. There was no post-crash fire. Lieutenant Commander Jack Kellicott, U.S. Navy, said that the airplane had run out of fuel.

Tex Johnston left Bell Aircraft Corporation and moved on to Boeing in Seattle, initially testing the swept-wing XB-47 Stratojet. He made the first flights of the YB-52 and XB-52 Stratofortress; the Model 367-80 (the “Dash 80”), which he notoriously rolled over Lake Washington, 6 August 1955; the KC-135A Stratotanker; and the Model 707 airliner. As Boeing’s Chief of Flight Test, Tex Johnston set the standard by which modern flight testing is carried out.

Alvin Melvin (“Tex”) Johnston, Chief of Flight Test. (The Boeing Company)

Highly recommended: Tex Johnston, Jet-Age Test Pilot, by A.M. “Tex” Johnston with Charles Barton, Smithsonian Books, Washington, D.C., 1991

© 2017, Bryan R. Swopes

Facebooktwittergoogle_plusredditpinterestlinkedinmailby feather