GB-4
{{Short description|American TV-guided bomb}}
{{Use American English|date=October 2024}}
{{Use dmy dates|date=October 2024}}
{{Infobox weapon
|name= GB-4 (Glide Bomb No.4)
|image= GB-4 Glide Bomb No 4.jpg
|caption=
|origin= United States
|type= Guided Bomb
|is_ranged=
|is_bladed=
|is_explosive=
|is_artillery=
|is_missile=yes
|is_UK=
|service= Combat Tested{{Cite report|title=Guidance and Homing of Missiles and Pilotless Aircraft|date=1946|publisher=AAF (US) Scientific Advisory Group, Wright Field|page=5|url=https://apps.dtic.mil/sti/citations/ADB807471|archive-url=https://web.archive.org/web/20220205143749/https://apps.dtic.mil/sti/citations/ADB807471|url-status=live|archive-date=5 February 2022}}{{Cite book|title=American Guided Missiles of World War II|last=Zaloga|first=Steven J|date=2020|publisher=Osprey|ISBN=9781472839275|pages=40–45}}{{Cite report|title=The Airforce and the National Guided Missile Program 1944-1950|last=Rosenberg|first=Max|date=1964|publisher=USAF Historical Liaison Office|page=11|url=https://archive.org/details/TheAirForceAndTheNationalGuidedMissileProgram}}
|used_by=
|wars= World War II
|designer=
|design_date=
|manufacturer=
|unit_cost=
|production_date=1944
|number=1,200
|variants=
|weight= {{convert|2535|lb|kg|abbr=on}}
|length= {{convert|12.2|ft|m|abbr=on}}
|part_length=
|width=
|height=
|diameter= {{convert|24|in|cm|abbr=on}}
|crew=
|filling=
|filling_weight={{convert|2000|lb|kg|abbr=on}}
|detonation= T62 Impact Fuze
|yield=
|armour=
|primary_armament=AN-M66 General Purpose Bomb
|secondary_armament=
|engine= none
|engine_power=
|transmission=
|payload_capacity={{convert|2000|lb|kg|abbr=on}}
|fuel_capacity=
|pw_ratio=
|suspension=
|clearance=
|vehicle_range={{convert|17|mi|km|abbr=on}} Preferred
|speed={{convert|250-300|mph|km/h|abbr=on}}
|guidance= Block III (AN/AXT-2) television equipment and remote radio control
}}
GB-4 (Glide Bomb No.4) was a precision guided munition developed by the United States during World War II. GB-4s used a television guidance system with the weapon being steered by a TV bombardier operating a joystick in the launch aircraft.
The first GB-4s (then known as MX-607s) were tested at Eglin Air Force Base during August 1943. During testing the GB-4's circular error probable accuracy was found to be {{convert|200|ft|m}}.{{Cite report|title=OP 1664, US Explosive Ordnance, Volume 2|date=1947|publisher=Naval Sea Systems Command (NAVSEA)|page=559|url=https://archive.org/details/OP1664USExplosiveOrdnanceVolume2}} The type was ordered into production on 15 January 1944. Although approved for operational use, the typed suffered from reliability problems throughout testing.
The GB-4 was briefly used in combat by the 388th Bomber Group, based in eastern England, but its performance was deemed unsatisfactory. 1,200 GB-4's were delivered to the USAAF however poor combat results lead to a decision to halt further deliveries in February 1945.