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Ground-directed bombing (GDB) is a military tactic for airstrikes by ground-attack aircraft, strategic bombers, and other equipped air vehicles under command guidance from aviation ground support equipment and/or ground personnel (e.g., ground observers). Often used in poor weather and at night (75% of all Vietnam War bombings "were done with precision[ sic ] GDB"), [1] the tactic was superseded by an airborne computer predicting unguided bomb impact from data provided by precision avionics (e.g., GPS, GPS/INS, etc.) Equipment for radar GDB generally included a combination ground radar/computer/communication system ("Q" system) and aircraft avionics for processing radioed commands. [2]
A 21st century variant of ground-directed bombing is the radio command guidance for armed unmanned aerial vehicles to effect ground-directed release of ordnance (e.g., precision-guided munitions for bombing such as the AGM-114 Hellfire). [3]
In early 1945, ground-directed bombing was invented by Lt Col Reginald Clizbe, deputy commander of the 47th Bombardment Group (Light), using automatic tracking radar in Northern Italy for A-26C missions (e.g., in the Po Valley). [4] Development was by a team that included Donald H. Falkingham (who was awarded the Air Medal) [5] that modified radar plotting to transmit control commands to the pilot direction indicator (bomb release was eventually automated from the ground radar). [4] Similar to the ground training configuration in the US for bombardiers with the Norden bombsight, in a tent near the SCR-284 radar [6] a bombsight was automatically positioned over a large map by the plotting signals converted from the radar track's spherical coordinates from the SCR-284 ranging and antenna pointing circuits. The guidance signals output from the moving bombsight as it viewed the map were then relayed to the aircraft as if the bombsight were on board (e.g., to a 1945 AN/ARA-17 Release Point Indicator). [7]
Post-war, ground radar command guidance was common for missiles designed to bombard ground targets, such as the AN/MSQ-1A with alternating current analog computer initially used for guidance of the MGM-1 Matador [8] (the Republic-Ford JB-2 Loon had used ground radar guidance in 1945, [9] and a few V-2s bombarding England used radio control in 1944.)
Korean War GDB equipment of the United States Marine Corps included the AN/MPQ-14, and GBD in Korea "was first tried on November 28 [1950], when a detachment of the 3903d Radar Bomb Scoring Squadron used truck-mounted AN/MPQ-2 radars [derived from the World War II SCR-584 gun laying set] [10] to guide B–26s against enemy positions in front of the 25th Infantry Division." [11] Three USAF RBS detachments (e.g., Det 5) [12] commanded GDB until the 502nd Tactical Control Group "assumed control of the 3903's three MPQ-2 radar sets" in January 1951, [13] and the radar sites "became full-scale tactical air-direction posts called Tadpoles [code]-named Hillbilly, Beverage, and Chestnut,…about ten miles behind the front lines near the command posts of the I, IX, and X Corps." [11] On February 23, 1951, the 1st Boeing B-29 Superfortress mission controlled by an MPQ-2 was flown, [14] and a new [ who? ] AN/MSQ-1 Close Support Control Set was at Yangu, Korea, by September 1951 [15] (AN/MPS-9 with OA-132 plotting computer & board). [16] The similar [ who? ] AN/MSQ-2 Close Support Control Set also developed by Rome Air Development Center [17] (MPS-9 radar & OA-215) [16] began arriving in 1951 (in October, [18] one GDB detachment that hadn't been provided MSQ-2 Technical Orders mistakenly bombed itself by using MSQ-1 procedures.) [19] Korea GDB operations of 2380 & 204 respective daylight & nighttime raids included 900 flown by USMC Vought F4U Corsairs. [13]
Vietnam War GDB equipment included the USMC AN/TPQ-10 "Course Directing Central" and the United States Air Force "Bomb Directing Centrals" with bomb ballistics computer by Reeves Instrument Corporation (AN/MSQ-77, AN/TSQ-81, & AN/TSQ-96) for Combat Skyspot. From 1966-1971, ASRTs controlled more than 38,010 AN/TPQ-10 missions, directing more than 121,000 tons of ordnance on 56,753 targets [20] (e.g., during the USMC "Operation Neutralize" bombing campaign against the North Vietnamese' siege of "Con Thien"). [21] In addition to Arc Light B-52 airstrikes, GDB during the war was used against Cambodia targets of Operation Menu from Bien Hoa Air Base and by Operation Niagara, [22] while Commando Club was used for GDB of the Red River Delta (e.g., Hanoi).
Post-Vietnam War GDB Strategic Air Command missions were occasionally used for training/readiness, e.g., to maintain proficiency of aircrews and SAC's GDB-qualified technicians at 1st Combat Evaluation Group RBS sites. A new GBD system developed c. 1980 from the [ who? ] AN/TPB-1C Course Directing Central was the solid-state US Dynamics AN/TPQ-43 Bomb Scoring Set which included optical tracking. The AN/TPQ-43 ("Seek Score") replaced the AN/MSQ-77, -81, & -96 systems at the end of the Cold War [23] before being decommissioned in 2007, [24] and GDB systems were also designated for use during airdrops as part of the Ground Radar Aerial Delivery System (GRADS). [25]
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Rome Laboratory is the US "Air Force 'superlab' for command, control, and communications" research and development and is responsible for planning and executing the USAF science and technology program.
A counter-battery radar or weapon tracking radar is a radar system that detects artillery projectiles fired by one or more guns, howitzers, mortars or rocket launchers and, from their trajectories, locates the position on the ground of the weapon that fired it. Such radars are a subclass of the wider class of target acquisition radars.
Operation Niagara was a U.S. Seventh Air Force close air support campaign carried out from January through March 1968, during the Vietnam War. Its purpose was to serve as an aerial umbrella for the defense of the U.S. Marine Corps Khe Sanh Combat Base on the Khe Sanh Plateau, in western Quang Tri Province of the Republic of Vietnam. The base was under siege by an estimated three-divisional force of the People's Army of Vietnam (PAVN).
The 1st Combat Evaluation Group was a Strategic Air Command (SAC) unit. It was formed on 1 August 1961 to merge the 3908th Strategic Standardization Group for SAC aircrew evaluation with the 1st Radar Bomb Scoring Group that had originated from the 263rd Army Air Force Base Unit which transferred from 15th AF to directly under Strategic Air Command c. 1946. The 1CEVG formed after SAC switched to low-level tactics to counter Soviet surface-to-air missiles and SAC had "developed a Radar Bomb Scoring field kit for use in NIKE Systems" in early 1960 for scoring SAC training missions against US Hercules SAM sites. The 1CEVG headquarters included an Office of History and a "standardization and evaluation school" for command examiners.
The 502d Air Operations Group in an inactive United States Air Force unit. It was last active in October 2006 at Hickam Air Force Base, Hawaii, where it had served as the umbrella for intelligence and operational support units under Pacific Air Forces
The Reeves AN/MSQ-77 Bomb Directing Central, Radar was a United States Air Force automatic tracking radar/computer system for command guidance of aircraft. It was often used during Vietnam War bomb runs at nighttime and during bad weather. Developed from the Reeves AN/MSQ-35, the AN/MSQ-77 reversed the process of Radar Bomb Scoring by continually estimating the bomb impact point before bomb release with a vacuum tube ballistic computer. Unlike "Course Directing Centrals" which guided aircraft to a predetermined release point, the AN/MSQ-77 algorithm continuously predicted bomb impact points during the radar track while the AN/MSQ-77's control commands adjusted the aircraft course. A close air support regulation prohibited AN/MSQ-77 Combat Skyspot bombing within 1,000 yd (910 m) of friendly forces unless authorized by a Forward Air Controller, and "on several occasions" strikes were as close as 273 yd (250 m).
Radar Bomb Scoring is a combat aviation ground support operation used to evaluate Cold War aircrews' effectiveness with simulated unguided bomb drops near radar stations of the United States Navy, the USAF Strategic Air Command, and Army Project Nike units. USAF RBS used various ground radar, computers, and other electronic equipment such as jammers to disrupt operations of the bomber's radar navigator, AAA/SAM simulators to require countermeasures from the bomber, and Radar Bomb Scoring Centrals for estimating accuracy of simulated bombings. Scores for accuracy and electronic warfare effectiveness were transmitted from radar sites such as those at Strategic Range Training Complexes.
The Reeves AN/MSQ-35 Bomb Scoring Central was a United States Air Force dual radar system with computerized plotting board. It was used by the 1st Combat Evaluation Group to evaluate the accuracy of Strategic Air Command bomber crews.
Lima Site 85 was a clandestine military installation in the Royal Kingdom of Laos guarded by the Hmong "Secret Army", the Central Intelligence Agency, and the United States Air Force used for Vietnam War covert operations against communist targets in ostensibly neutral Laos under attack by the Vietnam People's Army. Initially created for a CIA command post to support a local stronghold, the site was expanded with a 1966 TACAN area excavated on the mountaintop where a 1967 command guidance radar was added for Commando Club bombing of northern areas of North Vietnam. The site ended operations with the Battle of Lima Site 85 when most of the U.S. technicians on the mountaintop were killed, including CMSgt Richard Etchberger. For his heroism and sacrifice, Etchberger received the Air Force Cross posthumously. The operation remained classified, however, and the existence of the award was not publicly acknowledged until 1998. After the declassification of LS 85 and a reevaluation of his actions, Etchberger was awarded the Medal of Honor in 2010.
Combat Skyspot was the ground-directed bombing (GDB) operation of the Vietnam War by the United States Air Force using Bomb Directing Centrals and by the United States Marine Corps using Course Directing Centrals. Combat Skyspot's command guidance of B-52s and tactical fighters and bombers—"chiefly flown by F-100's"—at night and poor weather was used for aerial bombing of strategic, close air support, interdiction, and other targets. Using a combination radar/computer/communications system at operating location in Southeast Asia, a typical bombing mission had an air command post turn over control of the mission to the radar station, and the station provided bomb run corrections and designated when to release bombs.
Reeves Instrument Corporation (RICO) was a Cold War manufacturer of computer and radar systems for the United States. The corporation was the Project Cyclone laboratory operator for simulation of guided missiles, and RICO developed several Strategic Air Command combination (radar/computer/communications) systems.
The AN/MPQ-2 Close Cooperation Control Unit was a truck-mounted pautomatic tracking radar/computer/communication system for aircraft command guidance, e.g., missile tracking, and for Radar Bomb Scoring. It was introduced shortly after the end of World War II. For ground directed bombing (GDB), an operator would manually plot a target on the "Blind Bombing Plotting Sheet", then use the manual "E6B computer and bombing tables" to plot the release point for striking the target, after which a radar operator used the AN/MPQ-2 to acquire a track of the bomber near an initial point during which allowed ground control of the bomb run to the release point.
The Western Electric M-33 Antiaircraft Fire Control System was an X-Band "Gunfire Control Radar", for aiming antiaircraft artillery by computer control. Developed for mobility via 3 trailers, the "M-33 system could compute, for the 90-mm. and 120-mm. guns, firing data for targets with speeds up to 1,000 mph", and for targets at 120,000 yards had similar gun laying accuracy as "SCR-584 type radars" at 70,000 yards. The system included a telescopic "target selector" on a tripod near the guns for additional measurement of aircraft "azimuth and elevation data [to] be transmitted to the computer and utilized as gun directing data."
The AN/TPQ-2 Close Air Support System was a post-World War II radar/computer/communications system for automatically tracking an aircraft and guiding it to a predetermined bomb release point. The system was the predecessor of the General Electric AN/MPQ-14 Course Directing Central deployed to the Korean War for ground-directed bombing.
Matador Automatic Radar Control (MARC) was a command guidance system for the Martin MGM-1 Matador ground launched cruise missile that used combination radar/computer/communication centrals for ground-directed bombing. As for the earlier ground central used with the X-10 aircraft,* MARC had an "Air Link" from the ground for control and an airborne AN/APW-11A radar transponder on the missile for ranging. A series of "MSQ sites". each with a mobile AN/MSQ-1A central in 3 vans had an automatic tracking radar to geolocate the Matador up to ~600 nmi. MARC provided command guidance during the "mid-course phase" after Matador/MARC contact was established following the missile launch off the Zero Length Launcher and until an MSQ transmitted the dive ("dump") command to start the flight path toward the target. Originating in the Caltech/Martin "ZEL Project" and developed as part of weapon system "Project MX 771" at the "Air Force Missile Test Center, Cocoa, Florida"; MARC had accuracy at "crossover into enemy territory" of ~500 ft (150 m) and—at an AN/MSQ-1A range of 165 nautical miles —a CEP of 2,700 ft (820 m).
The Reeves AN/MSQ-51 Aerial Target Control Central (ATCC) was a combination radar/computer/communications system developed 1961-3 for United States Navy "aerial target out-of-sight control". In addition to the "Target Control System AN/SRW-4D" with radios and "Antenna Assemblies for Target Control and Communications ", the ATCC included acquisition/surveillance and tracking radars, a Mark X IFF/SIF, and an analog computer. The ATCC's automatic tracking radar was derived from the Western Electric M-33 gun laying radar and could process double-pulse 9340-9370 MHz beacon returns from transponders up to 400,000 yd away from the AN/MSQ-51 transmitting 9215-9285 MHz radar pulses. If an ATCC was equipped with a "Telemetry Receiving Station", IRIG channels 5-14 could also be received from QF-9G and Q-2C unmanned aerial vehicles. Other ATCC-controlled drones included the QF-9F, KDA-1, KDA-4, KDB-1 and KD2R-5. For "RF communications " to command the drone was a "Collins Radio Co. Model 618T-3" Single Sideband Transceiver (SST) with Control Unit 714E-2 for 28,000 channels. The 1000 watt voice radio system had 2 UHF AN/GRC-27 sets "with Control-Indicator 6-806/GR" for 1750 channels
The 3903rd Radar Bomb Scoring Group was a military evaluation unit under direct command of Strategic Air Command (SAC) headquarters for scoring simulated bomb runs using automatic tracking radar stations. Initially an Army Air Forces Base Unit (AAFBU) and then a squadron, the 3903rd RBS Group was personnel, assets, and detachments were redesignated the 1st Radar Bomb Scoring Group and then the 1CEVG Radar Bomb Scoring Division when the RBS Group merged with the 3908th Strategic Standardization Group in 1961, the year RBS Express trains began to be used for low-altitude Boeing B-52 Stratofortress operations..
The Reeves AN/TSQ-96 Bomb Directing Central was an automatic tracking radar/computer/communications system. The United States Air Force used it from the 1960s, including during the Vietnam War.
The Reeves AN/MSQ-1 Close Support Control Set produced by Reeves Instrument Corporation was a trailer-mounted combination radar/computer/communication developed under a Rome Air Development Center program office for Cold War command guidance of manned aircraft Developed for Korean War ground-directed bombing, one detachment of the 3903rd Radar Bomb Scoring Squadron bombed itself with an MSQ-1 because it mistakenly used procedures for the earlier SCR-584/OA-294 system The MSQ-1 was subsequently used for nuclear testing during Operation Teapot, and for aircraft tests such as for "MSQ-1 controlled pinpoint photography" in 1954.
The General Electric AN/TPQ-1O Course Directing Central was a light-weight, two-unit, helicopter transportable, ground based bombing system developed for use by the United States Marine Corps to provide highly accurate, day/night all weather close air support. This self-contained system was designed to guide an aircraft, equipped with the proper control equipment, to a release point for accurate all-weather delivery of ordnance and supplies to a preselected target. The AN/TPQ-10 and its operators were known as an ‘’Air Support Radar Team’’ (ASRT) and were employed by the Marine Air Support Squadrons within the Aviation Combat Element.
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: CS1 maint: archived copy as title (link)Won his first Air Medal while working with Col. Clizby in developing a means to bomb close support to the troops using ground control radar.NOTE: "bombing by radar-control" is identified in a "19 February 1945" listing of the Combat Chronology.
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: CS1 maint: archived copy as title (link)On the MSQ-1, we operated in the same manner, but later learned that [for the "brand new MSQ-2 plotting equipment"] we should have entered the target coordinates into the new digital/analog computer, AND THEN 'ZEROED' THEM OUT AGAIN. The computer would remember the offset and track accordingly. Unfortunately, we did not know that without the TO's. By leaving them in, like the 584, we effectively located the target's position over the top of ourselves.