History
On March 11, 1939, the Material Division of the US Army Air Corps issued “Circular Proposal” No. 39-775, calling for a new twin-engine, high-performance interceptor fighter. Four contractors submitted designs, one of which came from Lockheed. At the time, Lockheed’s XP-38 experimental prototype had crashed just weeks earlier, and the order for 13 YP-38 prototypes had not yet been fulfilled. With the company eager to secure further investment in the P-38 program, Lockheed pursued the opportunity to develop an advanced derivative of the aircraft.
Lockheed’s design team worked on what was initially designated as the Model 222, later reclassified as the Model 522. The design closely resembled the P-38 but introduced a pressurized cockpit and was powered by two turbocharged Pratt & Whitney X-1800-SA2-G liquid-cooled engines, each producing between 2,000 and 2,200 horsepower at takeoff. Fuel capacity was increased to 300 US gallons compared to the 230 gallons of early P-38 models. Proposed armament consisted of two 20mm cannons and four .50 caliber machine guns. The estimated top speed was 473 mph (761 km/h) at 20,000 feet (6,000 m) with the X-1800 engines. Should the Model 222 be approved for production, Lockheed planned to replace these engines with 2,300-hp Wright R-2160 Tornado radials, which were projected to boost the aircraft’s speed to 500 mph (800 km/h) at the same altitude.
The concept showed promise, and after evaluating the four competing proposals in August 1939, the Army announced Lockheed as the winner of the competition in October. A formal contract was awarded on January 8, 1940, for the construction of a single prototype, now designated XP-49. Grumman’s competing proposal, which placed second, was also approved as a backup and became the XP-50 Skyrocket. However, with Lockheed heavily involved in P-38 Lightning production, development on the XP-49 progressed slowly in early 1940. Design modifications were made to accommodate the larger and heavier engines, including redesigned nacelles, increased vertical tail surface area, and strengthened landing gear. By March 1940, it became apparent that both the Pratt & Whitney X-1800 and the Wright R-2160 were facing developmental delays. As a result, Lockheed and the Army opted to equip the XP-49 with Continental XI-1430-1 inline engines, which produced only 1,600 horsepower each, 400 horsepower less than originally planned. These engines were designed to rotate in opposite directions, with the port propeller spinning to the left and the starboard propeller to the right. Due to this engine downgrade, the estimated maximum speed was reduced to 458 mph (737 km/h) at 25,000 feet (7,600 m). The aircraft’s final detailed design was completed in December 1940, with modifications including the installation of a dummy armor plate of appropriate weight rather than actual armor. Ultimately, only 66% of the XP-49’s components were shared with the P-38.
With Lockheed prioritizing P-38 production, the XP-49 did not take its first flight until November 14, 1942, after overcoming delays caused by the Continental engine’s development issues. Its maiden flight lasted just 35 minutes, after which the aircraft was grounded for modifications. Testing resumed in December 1942 but was frequently interrupted by hydraulic system failures. Despite handling well and displaying good maneuverability, the XP-49’s Continental engines only allowed it to reach a top speed of 406 mph (653 km/h) at 15,000 feet (4,600 m), which turned out to be a disappointing result compared to the projected 458 mph at 25,000 feet.
On January 1, 1943, the XP-49 suffered an accident when its port landing gear collapsed during an emergency landing at Muroc Army Air Base, California, following hydraulic and electrical system failures. While undergoing repairs, the aircraft received enlarged vertical tail surfaces, and efforts were made to improve hydraulic reliability. The XP-49 resumed flying on February 16, 1943, and was delivered to Wright Field on June 26, 1943, almost 27 months behind schedule. By this time, the Army had lost interest in the XP-49, as its performance was inferior to the standard P-38J Lightning already in service. As a result, no further production was pursued, and the program was canceled. The sole XP-49 remained at Wright Field for occasional testing, but frequent engine maintenance issues and fuel system problems led to limited flight time. Eventually, the aircraft was repurposed for hard-landing tests, where it was dropped from a bridge crane. It was ultimately scrapped at Wright-Patterson Army Air Base in 1946.
