Staff Writer (Updated: 5/11/2016):
The XP-49 was visually similar in most respects to the P-38. The twin-boom design was found to be effective even for a fighter as in the P.38 and the XP-49 would follow suit. Beyond sharing this key physical characteristic, the XP-49 was of an new design. The aircraft was to feature a pair of Pratt & Whitney's new "X-1800" engine capable of an impressive 2,300 horsepower, offering the XP-49 airframe a maximum speed reaching nearing 500 miles per hour.
The single prototype was completed and first flown in November of 1942, sans all of its proposed armament to expedite development. The proposed weapons suite centered on 2 x 20mm cannons supported by 4 x 0.50 caliber Browning heavy machine guns - an improvement over the P.38's single 20mm cannon and 4 x .50 caliber gun array. As in the P-38, the XP-49 carried its armament concentrated at the nose section, ahead of the pilot's position.
While the XP-49 was being drawn up as a single-seat fighter, a second cockpit was added for an observer behind the pilot for flight testing.
New engines - the Continental XI-1430 - were then selected to succeed the intended (and now cancelled) Pratt & Whitney engines. This led to a reduction in estimated speed by as much as 75 miles per hour. The shift added to the project's woes which was beginning to lose steam as the war continued to turn to the favor of the Allies and the current stock of Army fighters were more than up to the task.
As such, the XP-49 led a very brief test life before running into further engine issues. As with the Pratt & Whitney engines, the developmental Continental engines were also cancelled. A crash landing during a flight test also took place when a landing gear failed to lower - such were the signs against the XP-49. With the cancellation of both intended engines, U.S. Army authorities eventually looked elsewhere, effectively leaving the XP-49 project dead on arrival.
In its final "moment of glory", the XP-49 airframe was subjected to brutish force-testing by being dropped at heights against a concrete floor. The tests were conducted to see the extent of damage caused by G-forces upon a modern aircraft fuselage. The XP-49 remains were later on display before being cannibalized and, ultimately, scrapped.