Warplanes of the USA: Northrop X-4 Bantam

Northrop X-4 Bantam

(USAF Photo)

The Northrop X-4 Bantam was a prototype small twinjet aircraft manufactured by Northrop Corporation in 1948. It had no horizontal tail surfaces, depending instead on combined elevator and aileron control surfaces (called elevons) for control in pitch and roll attitudes, almost exactly in the manner of the similar-format, rocket-powered Messerschmitt Me 163 of Germany's Luftwaffe. Some aerodynamicists had proposed that eliminating the horizontal tail would also do away with stability problems at fast speeds (called shock stall) resulting from the interaction of supersonic shock waves from the wings and the horizontal stabilizers. The idea had merit, but the flight control systems of that time prevented the X-4 from achieving any success. (Wikipedia)

Two X-4s were built by the Northrop Corporation, but the first was found to be mechanically unsound and after ten flights it was grounded and used to provide parts for the second. While being tested from 1950 to 1953 at the NACA High-Speed Flight Research Station (now Edwards Air Force Base), the X-4's semi-tailless configuration exhibited inherent longitudinal stability problems (porpoising) as it approached the speed of sound. It was concluded that (with the control technology available at the time) tailless craft were not suited for transonic flight.[2]It was believed in the 1940s that a design without horizontal stabilizers would avoid the interaction of shock waves between the wing and stabilizers. These were believed to be the source of the stability problems at transonic speeds up to Mach 0.9. Two aircraft had already been built using a semi-tailless design—the rocket-powered Me 163B Komet flown in combat by Germany's Luftwaffe in the Second World War, and the turbojet-powered British de Havilland DH.108 Swallow built after the war. The United States Army Air Forces signed a contract with the Northrop Aircraft Company on 11 June 1946, to build two X-4s. Northrop was selected because of its experience with flying wing designs, such as the N-9M, XB-35 and YB-49 aircraft.The resulting aircraft was very compact, only large enough to hold two Westinghouse J30 jet engines, a pilot, instrumentation, and a 45-minute fuel supply. Nearly all maintenance work on the aircraft could be done without using a ladder or footstool. A person standing on the ground could easily look into the cockpit. The aircraft also had split flaps, which doubled as speed brakes. (Wikipedia)

(NACA Photos)

Northrop X-4 Bantam (Serial No. 46-6676). 46-676, is on display at the Flight Test Museum on Edwards Air Force Base, Edwards, California.

(NACA Photo)

The NACA High-Speed Flight Research Station X-4 research aircraft is seen in this 1950s in-flight photograph flying near an approaching cloud bank.

(NMUSAF Photo)

Northrop X-4 Bantam (Serial No. 46-6677).

(NASA Photo)

The X-4’s design allowed it to be separated into two parts, aft of the engines, for servicing and instrumentation work.

(NASA Photo)

Northrop X-4 Bantam (Serial No. 46-6677).

In this 1950 view of the left side of the NACA High-Speed Flight Research Station's X-4 research aircraft, the low swept wing and horizontal taillest design are seen. The X-4 Bantam, a single-place, low swept-wing, semi-tailless aircraft, was designed and built by Northrop Aircraft, Inc. It had no horizontal tail surfaces and its mission was to obtain in-flight data on the stability and control of semi-tailless aircraft at high subsonic speeds.

(NMUSAF Photos)

Northrop X-4 Bantam (Serial No. 6677), on display at the National Museum of the United States Air Force in Dayton, Ohio. The X-4 on display in the NMUSAF was transferred to the museum shortly after the program ended in 1953.  It was restored by the Western Museum of Flight, Hawthorne, California.

(USAF Photo)

Boeing XB-52 bomber on flightline; with a Northrop X-4 Bantam in the foreground and a Convair B-36 Peacemaker in the background.

(NACA Photo)

NACA X-Planes on South Base ramp: Douglas D-558-2, Douglas D-558-1, Bell X-5, Bell X-1, Northrop X-4.  Back row Convair XF-92A. 30 March 1952.

(NACA Photo)

NACA High Speed Flight Station aircraft at South Base. Clockwise from far left: D-558-II, XF-92A, X-5, X-1, X-4, and D-558-I.

(NACA Photo)

First generation U.S. experimental aircraft. In the center, the Douglas X-3 Stiletto; around it, clockwise from bottom left: Bell X-1A, Douglas D-558-1 Skystreak, Convair XF-92A, Bell X-5, Douglas D-558-2 Skyrocket, Northrop X-4 Bantam.