Tag Archives: Allison Engineering Co. V-1710-11

11 February 1939

Wreck of the Lockheed XP-38 at Cold Stream, New York. (Associated Press)
Wreck of the Lockheed XP-38 at Cold Stream Golf Course, Hempstead, New York, 11 February 1939. (Associated Press)

11 February 1939: Barely two weeks after its first flight, First Lieutenant Benjamin Scovill (“Ben”) Kelsey, U.S. Army Air Corps, took the prototype Lockheed XP-38, 37-457, on a record-breaking transcontinental flight from March Field, Riverside, California, to Mitchel Field, Long Island, New York.

Lieutenant Kelsey departed March Field at 6:32 a.m., Pacific Standard Time, (9:32 a.m., Eastern) and flew to Amarillo, Texas for the first of two refueling stops. He arrived there at 12:22 p.m., EST, and remained on the ground for 22 minutes. The XP-38 took off at 12:44 p.m., EST, and Kelsey flew on to Wright Field, Dayton, Ohio. He landed there at 3:10 p.m. EST.

Kelsey was met by Major General H.H. Arnold, and it was decided to continue to New York. The XP-38 was airborne again at 3:28 p.m., EST, on the final leg of his transcontinental flight.

The prototype Lockheed XP-38 37-457, being refueled at Wright Field, Dayton, Ohio, during the transcontinental speed record flight, 11 February 1939. (Unattributed)
The prototype Lockheed XP-38, 37-457, being refueled at Wright Field, Dayton, Ohio, during the transcontinental speed record attempt, 11 February 1939. (Unattributed)

Kelsey was overhead Mitchel Field, New York at 4:55 p.m., Eastern Standard Time, but his landing was delayed by other airplanes in the traffic pattern.

On approach, the XP-38 was behind several slower training planes, so Lieutenant Kelsey throttled back the engines. When he tried to throttle up, the carburetor venturis iced and the engines would not accelerate, remaining at idle. The airplane crashed on a golf course short of the airport.

Wreckage of the prototype Lockheed XP-38 37-457 at Cold Stream Golf Course, Hempstead, New York, 11 February 1939. (Unattributed)
Wreckage of the prototype Lockheed XP-38, 37-457, at Cold Stream Golf Course, Hempstead, New York, 11 February 1939. (Unattributed)

The total elapsed time was 7 hours, 45 minutes, 36 seconds but Kelsey’s actual flight time was 7 hours, 36 seconds. The prototype had averaged 340 miles per hour (547 kilometers per hour) and had reached 420 miles per hour (676 kilometers per hour) during the Wright Field-to-Mitchel Field segment.

Kelsey’s transcontinental flight failed to break the transcontinental speed record set two years earlier by Howard R. Hughes by 17 minutes, 11 seconds. It should be noted, however, that Hughes H-1 Racer flew non-stop from coast to coast, while the XP-38 required two time-consuming fuel stops.

Wreck of the prototype Lockheed XP-38 37-457 on the Cold Stream Golf Course, Hempstead, New York, 11 February 1939. (Unattributed)
Wreck of the prototype Lockheed XP-38, 37-457, on the Cold Stream Golf Course, Hempstead, New York, 11 February 1939. (Unattributed)

The XP-38 was damaged beyond repair, but its performance on the transcontinental flight was so impressive that 13 YP-38s were ordered from Lockheed by the Air Corps.

Overhead view of the wrecked prototype Lockheed XP-38 37-457 at Cold Stream Golf Course, Hempstead, New York, 11 February 1939. (U.S. Army)
Overhead view of the wrecked prototype Lockheed XP-38, 37-457, at Cold Stream Golf Course, Hempstead, New York, 11 February 1939. (U.S. Army)

Designed by an engineering team led by Hall L. Hibbard, which included the legendary Clarence L. “Kelly” Johnson, the XP-38 was a single-place, twin-engine fighter designed for very high speed and long range. It was an unusual configuration with the cockpit and armament in a center nacelle, with two longitudinal booms containing the engines and propellers, turbochargers, radiators and coolers. The Lightning was equipped with tricycle landing gear. The nose strut retracted into the center nacelle and the two main gear struts retracted into bays in the booms. To reduce drag, the sheet metal used butt joints with flush rivets.

The XP-38 was 37 feet, 10 inches (11.532 meters) long with a wingspan of 52 feet (15.850 meters) and overall height of 12 feet, 10 inches (3.952 meters). Its empty weight was 11,507 pounds (5,219.5 kilograms). The gross weight was 13,904 pounds (6,306.75 kilograms) and maximum takeoff weight was 15,416 pounds (6,992.6 kilograms).

Lockheed XP-38 37-457. (San Diego Air and Space Museum Archive)

The Lightning was the first production airplane to use the Harold Caminez-designed, liquid-cooled, supercharged, 1,710.60-cubic-inch-displacement (28.032 liter) Allison Engineering Company V-1710 single overhead cam 60° V-12 engines. When installed on the P-38, these engines rotated in opposite directions. The XP-38 used a pair of experimental C-series Allisons, with the port V-1710-C8 (V-1710-11) engine being a normal right-hand tractor configuration, while the starboard engine, the V-1710-C9 (V-1710-15), was a left-hand tractor. Through a 2:1 gear reduction, these engines drove the two 11-foot (3.353 meters) diameter, three-bladed Curtiss Electric variable-pitch propellers inward to counteract the torque effect of the engines and propellers. (Viewed from the front of the airplane, the XP-38’s starboard propeller turned clockwise, the port propeller turned counter-clockwise. The direction of rotation was reversed in the YP-38 service test prototypes and production P-38 models.) The engines have long propeller gear drive sections to aid in streamlining aircraft, and are sometimes referred to as “long-nose Allisons.”

The V-1710-11 and -15 had a compression ratio of 6.65:1. They had a continuous power rating of 1,000 horsepower at 2,600 r.p.m. at Sea Level, and 1,150 horsepower at 2,950 r.p.m. for takeoff. The combination of a gear-driven supercharger and an exhaust-driven General Electric B-1 turbosupercharger allowed these engines to maintain their rated power levels to an altitude of 25,000 feet (7,620 meters).

The -11 and -15 were 7 feet, 10.46 inches (2.399 meters) long. The -11 was 3 feet, 6.59 inches (1.082 meters) high and 2 feet, 4.93 inches (0.7348 meters) wide. It weighed 1,300 pounds (589.7 kilograms). The -15 was 3 feet, 4.71 inches (1.034 meters) high, 2 feet, 4.94 inches (0.7351 meters) wide, and weighed 1,305 pounds (591.9 kilograms).

The XP-38 had a maximum speed of 413 miles per hour (664.66 kilometers per hour) at 20,000 feet (6,096 meters) and a service ceiling of 38,000 feet (11,582.4 meters).

The XP-38 was unarmed, but almost all production Lightnings carried a 20 mm auto cannon and four Browning .50-caliber machine guns grouped together in the nose. They could also carry bombs or rockets and jettisonable external fuel tanks.

Testing continued with thirteen YP-38A pre-production aircraft and was quickly placed in full production. The P-38 Lightning was one of the most successful combat aircraft of World War II. By the end of the war, Lockheed had built 10,037 Lightnings.

© 2017, Bryan R. Swopes

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27 January 1939

Lockheed XP-38 Lightning 37-457 at March Field, Riverside County, California, January 1939. (San Diego Air and Space Museum)
Lockheed XP-38 Lightning 37-457 at March Field, Riverside County, California, January 1939. (San Diego Air and Space Museum Archive)

27 January 1939: First Lieutenant Benjamin Scovill Kelsey, United States Army Air Corps, made the first flight of the prototype Lockheed XP-38 Lightning, serial number 37-457, at March Field, Riverside County, California.

First Lieutenant Benjamin S. Kelsey, USAAC, in the cockpit of a Curtiss P-36A Hawk, at Wright Field. (U.S. Air Force)
First Lieutenant Benjamin S. Kelsey, USAAC, in the cockpit of a Curtiss P-36A Hawk, at Wright Field. (U.S. Air Force)

This was a short flight. Immediately after takeoff, Kelsey felt severe vibrations in the airframe. Three of four flap support rods had failed, leaving the flaps unusable.

Returning to March Field, Kelsey landed at a very high speed with a 18° nose up angle. The tail dragged on the runway. Damage was minor and the problem was quickly solved.

Designed by an engineering team led by Hall L. Hibbard, which included the legendary Clarence L. “Kelly” Johnson, the XP-38 was a single-place, twin-engine fighter designed for very high speed and long range. It was an unusual configuration with the cockpit and armament in a center nacelle, with two longitudinal booms containing the engines and propellers, turbochargers, radiators and coolers. The Lightning was equipped with tricycle landing gear. The nose strut retracted into the center nacelle and the two main gear struts retracted into bays in the booms. To reduce drag, the sheet metal used butt joints with flush rivets.

Lockheed XP-38 Lightning 37-457. (San Diego Air and Space Museum)
Lockheed XP-38 Lightning 37-457. (San Diego Air and Space Museum Archive)

The prototype had been built built at Lockheed’s factory in Burbank, California. On the night of 31 December 1938/1 January 1939, it was transported to March Field aboard a convoy of three trucks. Once there, the components were assembled by Lockheed technicians working under tight security.

Lockheed XP-38 Lightning 37-457. (San Diego Air and Space Museum Archive)
Lockheed XP-38 Lightning 37-457. (San Diego Air and Space Museum Archive)
Left profile, Lockheed XP-38 Lightning 37-457. (U.S. Air Force)
Left profile, Lockheed XP-38 Lightning 37-457. (U.S. Air Force)
Lockheed XP-38 Lightning 37-457

The XP-38 was 37 feet, 10 inches (11.532 meters) long with a wingspan of 52 feet (15.850 meters) and overall height of 12 feet, 10 inches (3.952 meters). Its empty weight was 11,507 pounds (5,219.5 kilograms). The gross weight was 13,904 pounds (6,306.75 kilograms) and maximum takeoff weight was 15,416 pounds (6,992.6 kilograms).

The Lightning was the first production airplane to use the Harold Caminez-designed, liquid-cooled, supercharged, 1,710.60-cubic-inch-displacement (28.032 liter) Allison Engineering Company V-1710 single overhead cam 60° V-12 engines. When installed on the P-38, these engines rotated in opposite directions. The XP-38 used a pair of experimental C-series Allisons, with the port V-1710-C8 (V-1710-11) engine being a normal right-hand tractor configuration, while the starboard engine, the V-1710-C9 (V-1710-15), was a left-hand tractor. Through a 2:1 gear reduction, these engines drove the 11-foot (3.353 meters) diameter, three-bladed Curtiss Electric variable-pitch propellers inward to counteract the torque effect of the engines and propellers. (Viewed from the front of the airplane, the XP-38’s starboard propeller turned clockwise, the port propeller turned counter-clockwise. The direction of rotation was reversed in the YP-38 service test prototypes and production P-38 models.) The engines have long propeller gear drive sections to aid in streamlining aircraft, and are sometimes referred to as “long-nose Allisons.”

The V-1710-11 and -15 had a compression ratio of 6.65:1. They had a continuous power rating of 1,000 horsepower at 2,600 r.p.m. at Sea Level, and 1,150 horsepower at 2,950 r.p.m. for takeoff. The combination of a gear-driven supercharger and an exhaust-driven General Electric B-1 turbosupercharger allowed these engines to maintain their rated power levels to an altitude of 25,000 feet (7,620 meters).

The -11 and -15 were 7 feet, 10.46 inches (2.399 meters) long. The -11 was 3 feet, 6.59 inches (1.082 meters) high and 2 feet, 4.93 inches (0.7348 meters) wide. It weighed 1,300 pounds (589.7 kilograms). The -15 was 3 feet, 4.71 inches (1.034 meters) high, 2 feet, 4.94 inches (0.7351 meters) wide, and weighed 1,305 pounds (591.9 kilograms).

A 1939 Allison Engine Company V-1710-33 liquid-cooled, supercharged SOHC 60° V-12 aircraft engine at the Smithsonian Institution National Air and Space Museum. This engine weighs 1,340 pounds (607.8 kilograms) and produced 1,040 horsepower at 2,800 r.p.m. During World War II, this engine cost $19,000. (NASM)
A 1939 Allison Engine Company V-1710-33 liquid-cooled, supercharged SOHC 60° V-12 aircraft engine at the Smithsonian Institution National Air and Space Museum. This engine weighs 1,340 pounds (607.8 kilograms) and produced 1,040 horsepower at 2,800 r.p.m. During World War II, this engine cost $19,000. (NASM)

The XP-38 had a maximum speed of 413 miles per hour (664.66 kilometers per hour) at 20,000 feet (6,096 meters) and a service ceiling of 38,000 feet (11,582.4 meters).

The XP-38 was unarmed, but almost all production Lightnings carried a 20 mm auto cannon and four Browning .50-caliber machine guns grouped together in the nose. They could also carry bombs or rockets and jettisonable external fuel tanks.

Lockheed XP-38 37-457. (San Diego Air and Space Museum Archive)
Lockheed XP-38 37-457. (San Diego Air and Space Museum Archive)

The prototype XP-38 was damaged beyond repair when, on approach to Mitchel Field, New York, 11 February 1939, both engines failed to accelerate from idle due to carburetor icing. Unable to maintain altitude, Lieutenant Kelsey crash landed on a golf course and was unhurt.

Testing continued with thirteen YP-38A pre-production aircraft and was quickly placed in full production. The P-38 Lightning was one of the most successful combat aircraft of World War II. By the end of the war, Lockheed had built 10,037 Lightnings.

Lockheed test pilot Tony LeVier in the cockpit of P-38J-10-LO Lightning 42-68008. (Lockheed Martin)

© 2018, Bryan R. Swopes

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