Northrop X-4 Bantam

Northrop X-4 Bantam
Land	Usa
Rolle	Prototype af haleløse fly
Første flyvning	15. december 1948
Bygget	2

Den Northrop X-4 Bantam var en prototype lille twinjet fly fremstillet af Northrop Corporation i 1948. Den havde ingen vandrette haleflader, men var i stedet afhængig af kombinerede elevator- og krængningskontrolflader (kaldet elevoner) til kontrol i pitch and roll-holdninger, næsten nøjagtigt på samme måde som den raketdrevne Messerschmitt Me 163 fra Nazitysklands Luftwaffe i lignende format. Nogle aerodynamikere havde foreslået, at eliminering af den vandrette hale også ville fjerne stabilitetsproblemer ved hurtige hastigheder (kaldet stødstall) som følge af samspillet mellem supersoniske chokbølger fra vingerne og de vandrette stabilisatorer. Ideen havde fortjeneste, men flyvekontrolsystemerne på den tid forhindrede X-4 i nogen succes.

Kilde: 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

Northrop X-4 Bantam 01

Northrop X-4 Bantam 02

Northrop X-4 Bantam 04

Northrop X-4 Bantam 03

Northrop X-4 Bantam 05

Northrop X-4 Bantam 06

Northrop X-4 Bantam 07

Northrop X-4 Bantam 08

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)
Rolle	Experimental Aircraft (Transonic Stability Research)
National Origin	USA
Producent	Northrop Corporation
First Flight	15. december 1948
Besætning	1 Pilot
Wing Sweep	35 degrees
Længde	7.01 m (23 ft 0 in)
Vingefang	8.23 m (27 ft 0 in)
Højde	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.

Visninger : 1991