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.
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.
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.
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.
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).
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. Swopesby