The Lightning designed by Lockheed engineer Clarence "Kelly" Johnson and his team of designers, represented one of the most radical departures from tradition in American fighter development. The Lightning was a complete break-away from conventional airframe design, power, and at long last, armament. Not only did it have twice the power and almost twice the size of its predecessors, but with no less than four .50 cal. machine guns plus a 20 mm cannon, the P-38 had enough firepower to sink a ship--and sometimes did. Concentrated in the central fuselage pod, the guns fired parallel which eliminated a need for a propeller synchronizer.
The Lightning tricycle landing gear and twin-boom configuration completed the list of major deviations from what might he considered conventional Army fighters. In this respect, it was very unusual that the Lightning design progressed beyond the testing stage; such radical concepts seldom achieved production status. But the simple fact was that the P-38 design worked and the Army seemed to have found its dream plane in this 400 mph fighter. The XP-38, 37-457, was built under tight secrecy and made its maiden flight on January 27, 1939, with Air Corps test pilot and P-38 project officer, Lt. Benjamin S. Kelsey, at the controls. The P-38's performance justified Lockheed's investment of nearly $6,000,000 of its own funds to complete the prototype. The Army was so delighted with the big new fighter, it lifted the wraps of secrecy from the plane for a transcontinent al speed dash on February 11, 1939. This event was marred by a crash when Kelsey undershot the runway at Mitchell Field, NY. Kelsey survived the crash and remained an important part of the Lightning program. The airplane was written off, but Lockheed received a contract for thirteen YP-38s along with the usual list of improvements.
The XP-38 had been powered by two liquid cooled, Allison V-1710 engines turning 11 1/2 foot Curtiss Electric, inward turning, counter-rotating propellers. With the YP-38s and all subsequent Lightings, the propellers rotated outward negating torque when both engines were operating (A batch ordered by Britain did not have counter-rotating propellers.) One XP-38A was built with a pressurized cabin. Armament on the YPs was altered by replacement of two of the .50s with .30s, and the 20 mm cannon gave way to a 37 mm. But even before the YP-38s were completed, the original machine gun arrangement was standardized for production types. The first production order was 35 P-38Ds, followed by 210 P-3XEs which reverted back to the 20 mm cannon. These planes began to arrive in October 1941, just before America entered World War II. With the P-38D came self sealing fuel tanks and armor protection for the pilot. The Lightning was ready for war! A major problem surfaced with the loss of control in a dive caused by aerodynamic compressibilit y. During late spring 1941, Air Corps Major Signa A. Gilke encountered serious trouble while diving his Lightning at high-speed from an altitude of 30,000 ft (9,120 m). When he reached an indicated airspeed of about 320 mph (515 kph), the airplane's tail began to shake violently and the nose dropped until the dive was almost vertical. Signa recovered and landed safely and the tail buffet problem was soon resolved after Lockheed installed new fillets to improve airflow where the cockpit gondola joined the wing center section. Seventeen months passed before engineers began to determine what caused the Lightning's nose to drop. They tested a scale model P-38 in the Ames Laboratory wind tunnel operated by the NACA (National Advisory Committee for Aeronautics) and found that shock waves formed when airflow over the wing reached transonic speeds and became turbulent. Lockheed never remedied this problem but the firm did install dive recovery flaps under each wing in 1944 to restore lift and smooth the airflow enough to maintain control when diving at high-speed. The fastest of the Lightnings was the P-38J with a top speed of 420 mph, and the version produced in the greatest quantity was the "L", of which 3,735 were built by Lockheed and 113 by Vultee. The P-38L was powered by two 1,475 hp Allison V1710-111 engines. As with any long-term production aircraft, the P-38 underwent many modifications. The P-38J intakes under the engines were enlarged to house core-type intercoolers. The curved windscreen was replaced by a flat panel, and the boom mounted radiators were enlarged. Some were fitted with bombardier type noses, and were used to lead formations of bomb-laden P-38s to their targets. The P-38M was a two-seat radar-equipped night fighter, a few of which had become operational before the war ended. One interesting variation had an elevated tail assembly on upswept booms; another one had an elongated center pod and was used for airfoil evaluation.
The dimensions of the P-38 remained the same throughout production, its wing spanning 52 feet with an area of 328 square feet. overall length was 37 feet 10 inches; height was 12 feet 10 inches. The P-38L weighed 12,800 pounds empty and 17,500 pounds gross. Thus, the P-38 was the largest, heaviest, and fastest "P" type to date. An internal fuel capacity of 410 gallons could be increased to 1,010 gallons with two external drop tanks and gave the Lightning a range of 450 miles, making it the first fighter suitable as a long-range bomber escort. In addition to its devastating nose armament, the P-38 could carry up to 4,000 pounds of external weapons including bombs and rockets.
there is your history lesson for today :a26g:
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