Northrop X-4 Bantam

Northrop X-4 Bantam
Pays	Usa
Rôle	Prototype d’avion Tailless
Premier vol	Le 15 décembre 1948
Construit	2

Lla Northrop X-4 Bantam était un prototype de petit avion à deux jet fabriqué par Northrop Corporation en 1948. Il n’avait pas de surfaces de queue horizontales, dépendant plutôt des surfaces combinées de commande d’ascenseur et d’aileron (appelées elevons) pour le contrôle dans les attitudes de pas et de roulis, presque exactement à la manière du format similaire, rocket-powered Messerschmitt Me 163 de l’Allemagne nazie’s Luftwaffe. Certains aérodynamistes avaient proposé que l’élimination de la queue horizontale éliminerait également les problèmes de stabilité à des vitesses rapides (appelées décrochage de choc) résultant de l’interaction des ondes de choc supersoniques des ailes et des stabilisateurs horizontaux. L’idée était fondée, mais les systèmes de commande de vol de l’époque empêchaient le X-4 de tout succès.

Source: Northrop X-4 Bantam sur Wikipedia

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

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Northrop X-4 Bantam 09

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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)
Rôle	Experimental Aircraft (Transonic Stability Research)
National Origin	États-Unis
Fabricant	Northrop Corporation
First Flight	Le 15 décembre 1948
Crew	1 Pilot
Wing Sweep	35 degrees
Length	7.01 m (23 ft 0 in)
Envergure	8.23 m (27 ft 0 in)
Height	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.