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Douglas XP-48

1940 WORLD WAR 2 X-PLANE

Douglas XP-48 History

The concept of an economical, very light fighter captured war planners around the world even before the outbreak of World War II in September 1939. The United States Army Air Corps (USAAC) is a service that studies the prospects for such a fleet of aircraft designed as a "point defense solution" to the threat of an enemy bomber fleet.

Mass production of these fighters is inexpensive and the required quantities can be built quickly. Compact size, non-essential construction materials (i.e. wood) and appropriate weapons have been the focus of many reviews of such military aircraft.

As a private company, Douglas Aircraft selected a light fighter design to sell to the Army Air Force. Work began in 1939 with a simple, conventionally laid-out fuselage that allowed a pilot to sit amidships. The engine is mounted on the nose as usual, and the tail has a single-blade fin. The main aircraft is a straight monoplane, albeit a very slim design, and is positioned forward amidships. The landing gear has a more forward looking configuration that is trike (three legs) and retractable.

The main legs were mounted on the fuselage, which was quite unique for fighter jets at the time, when the main legs were usually attached to the main wing panels.

The engine of choice became a Ranger XV-770 V12 inverted liquid-cooled inline-piston engine with 525 horsepower. Mounted in a compartment in the handpiece, it drives a three-edged blade with a diameter of 9.5 feet.

The aircraft has a fuel capacity of only 50 gallons, as range should not be an issue for this point defense combat system.

Known internally as the Type 312, the aircraft was intentionally compact, measuring 21.8 feet long, with a wingspan of 32 feet and a height of 9 feet. Curb weight is 2,675 lbs and MTOW is 3,400 lbs.

In terms of armament, the engineers came up with the typical combination of the .30 caliber Browning medium machine gun and the 0.50 caliber Browning heavy machine gun of the timeboth air-cooled and belt-fed. These will be mounted on the nose (and engine) and fired synchronously by the rotating propeller blades.

Generally speaking, the airframe carries all the relevant systems - pilot, engines, avionics, fuel, landing gear and weapons. The raised top of the fuselage reduces rear visibility, but the plane almost always flies with the enemy ahead.

The fun tricycle landing gear may have added a technical challenge, requiring the pilot to hold the joystick steady while walking on the ground or landing/taking off.

Army authorities found the proposed Type 312 so valuable that a formal specification for the expected "XP-48" prototype was developed in August 1939. However, this Douglas design only survived for a short time, and the Army canceled the project as early as February 1940apparently, the 350 mph top speed promised by Douglas engineers was not convincing.

Another light point defense fighter project, the Tucker XP-57 (detailed elsewhere on this site) - also failed, the Bell XP-77 (detailed elsewhere on this site), at least another in the field Entry Point Two prototypes built it, and it stayed in the air for a while before it was discontinued (in 1944).