Conquering the Sky!

Air Classics, Apr 2005 by O'Leary, Michael

THE AMAZlNG SAGA OF THE LOCKED P-38 LIGHTNING/PART ONE

During the early 1930s, the United States Army Air Corps (USAAC) had a motley collection of combat aircraft -the fighters of the day were little more than glorified sport aircraft, built for a style of war that would never happen. Strategic bombing rested on the broad fabric wings of aircraft that would not have seemed out of place in the First World War.

A few far-sighted USAAC officers made appeals for new, dynamic aircraft which would inject life into a service made nearly dormant by the Great Depression. However, with so many pressing national needs, the government was reluctant to finance new aircraft.

From 1935 to 1937, the growing menace of Nazi Germany began to register among even the most isolationist American politicians, and some money began to reach the military for limited research and development on advanced aircraft projects.

One of these projects was a twin-engined interceptor capable of carrying a heavy armament to high altitudes, which would be attained with newly-developed turbosu-perchargers. The new design would have long range and be able to climb quickly to intercept high-flying bombers. A tricycle landing gear was specified to simplify ground handling. Titled Specification X-608, the requirement was circulated among interested aircraft manufacturers.

The specification was spearheaded by Lt. Benjamin Kelsey, a Massachusetts Institute of Technology graduate who, in 1934, had been appointed officer in charge of the Fighter Projects Office at Wright Field, Ohio.

The Lockheed Aircraft Corporation at Burbank, California, had developed a reputation for producing high-performance aircraft with advanced aerolynamics and an ability to grab records and headlines (see Air Classics July 2004), but lucrative government contracts were needed to assure stability and growth.

An earlier USAAC specification had put Kelsey in contact with Lockheed chief designer Hall Hibbard and his young assistant, Clarence "Kelly" Johnson. Kelsey was impressed by the aircraft the men designed for the proposal (it was Johnson's first crack at a military design), but Bell won the contract by the narrowest of margins with the rather hopeless FM-1 Airacuda.

Lockheed had been considering a high-performance military aircraft before the specification was issued, and had come up with a working proposal for the new aircraft, designated the Model 22 (also identified in period documents as Project M-12-36). The design inception date was March 1936.

Johnson looked at Specification X-608 and realized that the biggest handicap would be lack of a suitable powerplant. The LJSAAC required the new aircraft to climb to 20,000-ft in 6'inin and have a top speed of at least 360-mph at altitude. Long range was also required and it was specified that all fuel be carried internally. Working with Hibbard, Kelly immediately began making sketches of proposed aircraft. All of these early designs had two engines. One engine would simply not provide required performance.

Johnson chose the V-12 Allison V-1710 powerplant, which could develop at least 1000-hp (with good growth potential) while its low frontal area offered excellent streamlining. It was also the only American high-horsepower in-line engine in series production.

Hibbard and Johnson settled on a design that elegant twin booms with a nacelle mounted to the wing between the booms. Power was to come from Allison V-1710-Cs of 1150-hp each and high-altitude performance would be greatly enhanced by twin General Electric turbosuperchargers in the booms, connected to the engines by complex tubing and ducting. A tricycle landing gear, with the nose gear in the fuselage pod and the main gear in the spacious booms, was provided as required by the specification. The armament was housed in the nose of the nacelle.

Another advanced feature was the use of a buttjointed, flush-surface skin to give maximum streamlining. The Model 22 would also be the first production aircraft to have all of its control surfaces covered in aluminum rather than fabric. Johnson had almost completed the design of a thin-section wing when the concept had be dropped because it was impossible to accommodate the required quantity of fuel in the wing, and the USAAC unwisely refused to consider external tanks. In a report on the new design, Johnson devoted six pages to "compressibility effects" since he knew the aircraft would he entering unexplored aerodynamic territory.

Kelsey studied the tendered proposals. Impressed by the sheet power offered by the Model 22, he recommended that the USAAC issue a prototype contract to the Burbank firm. Bell also won a prototype contract for its single-engine design that would become the XP-39 Airacobra (see Air Classics September 2004).

The government issued Air Corps Contract No. 9974 to Lockheed on 23 June 1937, for the construction of one XP-38, allotted USAAC serial 37-457. The cost of the aircraft was to be $163,000. The company team was pleased with this, although they realized that the new plane was radical and one aircraft might not lead to production if the design did not perform as required.