JB-4

The JB-4, also known as MX-607, was an early American air-to-surface missile developed by the United States Army Air Forces during World War II. Using television/radio-command guidance, the JB-4 reached the flight-testing stage before being cancelled at the end of the war.

JB-4
TypeAir-to-surface missile
Place of originUnited States
Service history
In service1945
Used byUnited States Army Air Forces
Specifications
Mass3,000 pounds (1,400 kg)
Wingspan12 feet (3.7 m)
WarheadHigh explosive
Warhead weight2,000 pounds (910 kg) bomb
EngineFord PJ31 pulsejet
660 lbf (2.9 kN)
Operational
range
75 miles (121 km)
Maximum speed 445 mph (716 km/h)

Design and development

Developed under the project code MX-607 at Wright Field in Ohio,[1][2] the JB-4 was a modification of the GB-4 glide bomb,[1][3] which had entered service with the U.S. Army Air Forces in 1944.[4] Powered by a Ford PJ31 pulsejet engine, the JB-4 was intended to give an improved standoff range as opposed to its unpowered predecessor.[1] In addition, the addition of an engine made the missile capable of being ground-launched as well.[1] However the requirement to carry fuel for the engine meant that the size of the JB-4's warhead was limited to 750 pounds (340 kg),[5] compared to the 2,000 pounds (910 kg) bomb that formed the core of the GB-4.[6]

Utilising primarily plywood construction,[5] the JB-4 utilised television/radio-command guidance, with an AN/AXT-2 transmitter broadcasting a television signal from a camera in the missile's nose to a remote operator. The operator, viewing the transmitted picture, would then transmit commands to the missile via radio, correcting the missile's course to ensure striking the target.[1]

Operational history

The JB-4 entered the flight testing stage in January 1945.[1][7] The missile demonstrated the ability to cruise at over 400 miles per hour (640 km/h);[8] however, the television-guidance concept suffered from the limitations of the technology of the time, the pictures being difficult to make out in anything except completely clear weather.[4] The missile also suffered from reliability issues; these, combined with the end of World War II in August 1945, resulted in the termination of the project,[1] with none of the JB-4s built seeing operational service.[3]

References
Notes
  1. Parsch 2005.
  2. Ross 1951, p.115.
  3. Ordway and Wakeford 1960, p.186.
  4. Parsch 2003.
  5. Hanle 2007, p.268.
  6. Hanle 2007, p.114.
  7. Air Force Magazine, Volume 31. 1948. p.25.
  8. Gunston 1979, p.33.
Bibliography
  • Gunston, Bill (1979). The Illustrated Encyclopedia of the World's Rockets & Missiles. London: Salamander Books. ASIN B002K4M822.
  • Hanle, Donald J. (2007). Near Miss: The Army Air Forces' Guided Bomb Program in World War II. Lanham, MD: Scarecrow Press. ISBN 978-0-8108-5776-6.
  • Ordway, Frederick Ira; Ronald C. Wakeford (1960). International Missile and Spacecraft Guide. New York: McGraw-Hill. ASIN B000MAEGVC.
  • Parsch, Andreas (2003). "GB Series". Directory of U.S. Military Rockets and Missiles Appendix 1: Early Missiles and Drones. designation-systems.net. Retrieved 2011-02-02.
  • Parsch, Andreas (2005). "JB Series". Directory of U.S. Military Rockets and Missiles Appendix 1: Early Missiles and Drones. designation-systems.net. Retrieved 2011-02-04.
  • Ross, Frank (1951). Guided Missiles: Rockets & Torpedoes. New York: Lothrop, Lee & Shepard. ASIN B001LGSGX0.
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