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UH-1M Army Combat Helicopter (gunship)

The UH-1M is a utility helicopter which was converted from US Army UH-1Cs to an attack helicopter during the Vietnam era, and was since replaced by the AH-1 Cobra. The UH-1M was upgraded from the UH-1C models with a more powerful Lycoming T53-L-13B 1400 shp engine. The first three UH-1Ms were were equipped with the INFANT (Iroquois Night Fighter and Night Tracker) system for night operations. The remaining UH-1Ms were UH-1Cs with the T53-L-13B engine upgrade. As of 1989, a total of 211 produced prior to 1970 remained in US Army inventory. By that time no major improvementsto the Huey fleet were planned. Some product improvement efforts that addressed reliability, maintainability, and safety of flight issues were ongoing or planned. There were no plans to equip Hueys with air-to-air Stinger missiles. The UH-1M used in the attack helicopter role were phased out in the early 1990s.

The UH-1C / UH-1M is a utility type helicopter. The helicopter has a two-bladed, semi-rigid main rotor.The fuselage consists of two main sections, the forward section and the aft or tailboom section. Seating positions may be in a two to eleven place arrangement, with the pilot in the forward right-hand location. Conversion from passenger to cargo configuration may be accomplished by removal of the seats. The airframe has built- in work platforms and cowling that can be opened or removed for access to all major components.

The UH-1M Army helicopter gunships were equipped for night weapons firing. In early 1970 the US Army Concept Team in Vietnam evaluated the Iroquois Night Fighter and Night Tracker (INFANT) to determine its combat suitability for stability operations in RVN. The weapons system, which consisted of three major subsystems -- the Image Intensifier System, Night Vision (AN/ASQ-132), the UH-1M utility helicopter, and the M21 Armament Subsystem --, was evaluated as a whole. However, emphasis was directed toward the image intensifier system. The general purpose of the evaluation was to assess the military worth of INFANT; specific objectives were to determine the following: system capabilities and limitations, maintainability and reliability, human factors implications, employment methods, impact upon the five functions of land warfare, countermeasures taken against the system, and the effectiveness of US Navy formation lights when used on night attack helicopters.

A major problem encountered by US field commanders in Vietnam was obtaining accurate and timely intelligence. The US required means to find and fix an elusive enemy; one who utilized the cover of night in movement of troops and logistical supplies. Techniques were required to provide surveillance, both night and day, in areas in which it was unfeasible to continuously maintain combat operations. The desire to deny the enemy freedom of movement at night led helicopter units to experiment with a variety of lighting systems.

Although night helicopter assaults were rare in the early operations in Vietnam, the Army did work toward developing effective night techniques. Experience has shown that all missions and roles normally fulfilled by helicopters during daylight hours can be successfully completed in darkness by aircraft equipped with navigation aids and night vision devices. Vietnam proved that helicopters could be used at night to greatly increase U.S. maneuver superiority over the enemy. Most of the night combat assaults were made to reinforce units in contact with the enemy; however, they were also made to gain tactical surprise, position blocking forces, and set up ambushes.

In July 1969, the 25th Infantry Division devised and fabricated a night aerial weapons system known as Nighthawk. A Nighthawk consisted of a Xenon searchlight (the same one that was used on a Sheridan), a night observation device (NOD) mounted coaxially with the searchlight on a manually controlled frame, and a separate, pintle mounted, 7.62mm minigun. The system was mounted on either side of a UH-1D/H helicopter, required very little crew training, and was easy to construct, given the appropriate assets.

Normal use involved a Nighthawk team (one UH-1D/H with the light and one or two AH-1G gunships) working either an area or specific targets already pinpointed through other methods. Ground controlled approach radar was often used to provide navigational assistance to the team. The UH-1D/H would fly at fifty knots 500 feet above the terrain with the gunships to the rear at about 1,500 feet. When the light ship detected a target with infrared light, it could either turn on the white light or open fire with the minigun, with the accompanying gunships then firing into the minigun's tracer pattern. The Nighthawk was very effective in flat, open terrain. In mountainous, canopied jungle it was limited to roads, trails, and Rome plow cuts. Nighthawk was employed to a limited extent in base camp defense, in checking out radar sightings, in sensor activity, and in mechanical ambushes.

The Iroquois Night Fighter and Night Tracker (INFANT) arrived in USARV in November 1969. The INFANT was capable of both acquiring and attacking a target at night. There are two image intensifier tubes, one with a direct-viewing fiber optic bundle and one with a TV camera tube, mounted on the front of a UH-IM helicopter. Two remote TV sets were mounted inside the aircraft. Mounted on each side of the aircraft were a minigun and a seven-tube 2.75 inch rocket launcher. Mounted on top of each minigun was a xenon search-light with a pink filter which could be used to supplement available ambient light when required. Three INFANT systems, developed under the ENSURE program, were deployed to USARV. These were used during a 90-day evaluation by ACTIV. The systems, to include a 16-man new equipment training team (NETT), were attached to the 1st Cavalry Division for the evaluation period which lasted until 28 February 1970. It was concluded that INFANT is an effective, covert, night weapons system; however some questioned its cost effectiveness when compared to the Nighthawk.

The Nighthawk [an in-country fabricated system.] and INFANT systems provided field commanders an excellent combination of aircraft and equipment for acquiring and engaging targets at night, both covertly and overtly. The refined INFANT equipment was tested in night combat operations in the III and IV Corps Tactical Zones. INFANT increased the ability of the helicopter to perform its attack and surveillance operations at night. The UH-1 also provided day convoy cover / reconnaissance during unit moves. The mission involved low-level and nap-of-the-earth operations in the vicinity of the convoy route. The aircraft would be flown approximately 40 feet above trees at 20 knots airspeed.

The requirement to achieve high accuracy with free rockets fired from rotary wing aircraft had been thwarted to a great extent by launch transients attributable to the aircraft. These transients, principally vibration, rotor downwash, and translation and rotation of the launch platform, had initially not been properly investigated as sources of rocket dispersion. Knowing the properties of the environment which the rocket must traverse, one may then use aerodynamic forces derived therefrom in simulating the rocket's trajectory. By 1975 computer codes existed which were intended to provide a theoretical capability to define the helicopter downwash fluid mechanical properties. The position of the boundaries of the rotor wake is strongly influenced by the aircraft's airspeed. For rockets launched from the helicopter ir a conventional fashion, there exists a maximum airspeed for which the rotor downwash intersects the rocket's flight path. It was desirable to determine these downwash boundaries as a function of forward velocity before proceeding with the velocity survey in order to more efficiently allocate the flight time available to meaningful explorations, and to better interpret the measurements once completed.

Over the course of almost 12 years of civil war in El Salvador, the Air Force played an increasingly important counterinsurgency role. Air strikes helped stem the guerrilla offensive in November 1989, and close air supportfrequently has enabled govemment forces to prevail in clashes with the rebels. To neutralize the govemment‘s air power, the insurgents obtained surface-to-air missiles (SAMs), mainly from Nicaragua and Cuba. Since their first successful missile kill--the shoot-down of an A-378 ground-attack aircraft--on 23 November 1990, the rebels used SAMs to down an AC-47 ?xed-wing aircraft and a UH~1M helicopter gunship.

The UH-1Ms were acquired “as is” by the Salvadoran air force (Fuerza Aérea Salvadoreña [FAS, in its Spanish acronym]). That meant that sometimes they were taken directly from boneyards in the United States and made airworthy again. The rationale to request Cobra helicopters was due more to the problems associated with maintaining the UH-1Ms than to power hunger. In 1995 a decision was made to remove all UH-1Ms and half of the UH-1Hs from the flight lines due to problems associated with spare parts and maintenance.

The UH-1M was designated nonstandard in 1993 only because by that time the U.S. Army Materiel Command (AMC) at the White Sands Missile Range (WSMR) was the sole operator of the aircraft. Although non-standard, the only authorized deviation from standard aircraft operating practices was the use of an aircraft of similar design, operation,and flight characteristics for evaluation purposes when a UH-1M is not available.

The US Army conducts Aerial Target Flight Operations and Maintenance Services at Fort Bliss, Texas; White Sands Missile Range (WSMR), New Mexico; and other Post, Camps and Stations (PCS) in the Continental United States (CONUS) and Outside CONUS in support of Subscale Target Systems (MQM-107, BQM-34, UAV-T), Ballistic Target Systems (BATS and TBMTT), Full Scale Rotary Wing Target (QUH-1M/UH-1M), and Subscale Rotary Wing Target (QH-50).




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Page last modified: 13-08-2012 11:06:02 ZULU