Northrop X-4 Bantam

Northrop X-4 Bantam
Land	Usa
Roll	Prototyp av ett flygplan utan svans
Första flygningen	den 15 december 1948
Byggd	2

Den Northrop X-4 Bantam var en prototyp av ett litet twinjet-flygplan som tillverkades av Northrop Corporation 1948. Den hade inga horisontella stjärtytor, utan var istället beroende av kombinerade höjd- och skevroderkontrollytor (kallade elevoner) för kontroll i pitch and roll-attityder, nästan exakt på samma sätt som den raketdrivna Messerschmitt Me 163 av liknande format från Nazitysklands Luftwaffe. Vissa aerodynamiker hade föreslagit att ett avskaffande av den horisontella svansen också skulle eliminera stabilitetsproblem vid höga hastigheter (så kallad chockstall) till följd av interaktionen mellan överljudschockvågor från vingarna och de horisontella stabilisatorerna. Idén hade sina förtjänster, men den tidens flygkontrollsystem hindrade X-4 från att nå framgång.

Källkod: Northrop X-4 Bantam på Wikipedia

Northrop X-4 Bantam Walk Aroundd
Photographers	John Heck, Randy Ray
Localisation	National Museum of the USAF
Photos	50

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General Characteristics and Role

The Northrop X-4 Bantam was an experimental jet aircraft developed for the U.S. Air Force and the National Advisory Committee for Aeronautics (NACA, the precursor to NASA) in the late 1940s. Its primary role was to investigate the aerodynamic properties of a tailless aircraft design at transonic speeds (speeds approaching the speed of sound, or Mach 1). It utilized a semi-tailless configuration, meaning it lacked a horizontal tail stabilizer but retained small vertical fins. The tailless design was believed to reduce the shock waves and control issues experienced by conventional aircraft as they approached the sound barrier. The Bantam was built as a small, swept-wing jet to minimize costs and complexity during the high-risk transonic research phase.

Property	Typical Value (X-4)
Roll	Experimental Aircraft (Transonic Stability Research)
National Origin	USA
Tillverkare	Northrop Corporation
First Flight	den 15 december 1948
besättning	1 Pilot
Wing Sweep	35 degrees
längd	7.01 m (23 ft 0 in)
Spännvidd	8.23 m (27 ft 0 in)
höjd	4.52 m (14 ft 10 in)	Gross Weight	3,524 kg (7,770 lb)

Powerplant and Flight Controls

Engine: 2 x Westinghouse J30 turbojet engines.
Thrust (Total): Approximately 1,600 lbf (7.1 kN).
Maximum Speed: 1,032 km/h (641 mph, or approx. Mach 0.85).
Control Surfaces: All control was handled by elevons (control surfaces that combine the functions of elevators and ailerons) on the trailing edge of the wing, and twin vertical rudders.
Stability Issue: Testing confirmed that while the X-4 was stable at low speeds, it experienced severe longitudinal stability issues when flying faster than Mach 0.88, leading to a tendency to pitch up and lose control.

Program Outcome and Legacy

Test Program: The X-4 completed 81 research flights at the NACA Muroc Flight Test Unit (later Edwards AFB).
Discovery: The program proved that a simple tailless design was unsuitable for sustained transonic flight due to the poor stability characteristics encountered.
Influence: This finding was crucial, convincing designers to use a conventional horizontal stabilizer (tailplane) or the all-moving stabilator on high-speed jets, which became the standard design for supersonic aircraft.
Preservation: Both prototypes built are preserved: one (46-676) is at the U.S. Air Force Museum in Ohio, and the other (46-677) is at the National Museum of Nuclear Science & History in New Mexico.