Emerson Electric’s Tactical Armament Turret Line for Aircraft
By Joseph Trevithick
The Emerson Electric Company was founded in 1890 in St. Louis, Missouri as the Emerson Electric Manufacturing Company. The company initially produced electric motors and then went on to produce entire electricity powered machines like fans, sewing machines, and power tools. By the time the Second World War broke out, Emerson turned its already half century of experience with electric power into lucrative defense contracts.
One of the most notable products that Emerson made during the Second World War was power turrets for aircraft. The U.S. strategy of daylight aerial bombing raids over occupied Europe led to a demand for improved defensive armament for bomber aircraft. Emerson joined other companies like Bendix, Erco, Martin, and Sperry to produce powered turrets for various Allied bomber aircraft. Among these was the Emerson Model 250 bow turret, which was used by the U.S. Army Air Forces and the U.S. Navy on Consolidated B-24J and PBY aircraft respectively.
After the end of the Second World War, Emerson’s work with the U.S. military continued. By the end of the 1950s, Emerson had become one of the companies cooperating with U.S. Army efforts to develop armament subsystems for helicopters, a relatively new frontier at the time. One of the first standardized armament subsystems for U.S. Army helicopters, the M6 armament subsystem for the UH-1 series of helicopters, began with work Emerson started in 1958.
The M6 was a fully powered weapon system, involving two sponsons mounted on each side of the aircraft, each mounting two 7.62mm M60C machine guns. The mounts could be elevated eleven degrees and depressed sixty-three degrees. The mounts could also be traversed inboard twelve degrees and outboard seventy degrees. A safety mechanism prevented the guns from traversing inboard enough to fire into the aircraft fuselage. This was all controlled from the co-pilot’s station, which was fitted with a flexible sighting system. The guns could also be locked in a forward position and fired by the pilot. Emerson later developed a variant of this subsystem, which also allowed for the carriage of 2.75-inch rocket pods. Further variants were developed from these, replacing the four M60C machine guns with two 7.62mm M134 “Miniguns.” The Minigun and rocket combination, which was designated the M21 armament subsystem, became one of the most popular armament combinations for UH-1 gunships during the conflict in Vietnam.
Emerson did not stop there, however. During the 1960s and 1970s, Emerson developed an entire line of powered turrets for aircraft, primarily helicopters. Emerson marketed these systems both to the U.S. military and overseas as part of the Tactical Armament Turret (TAT) line. Emerson’s in-house nomenclature designated these systems with the prefix TAT followed by a three digit number. The TAT family included aircraft turrets, as well as turrets for land vehicles and ships and other watercraft. Some turrets were marketed as being readily suitable for use in various environments.
Few products from Emerson’s TAT line met with significant success and many never progressed beyond the developmental stage, possibly never making it off the drafting table. While the TAT line was a major product offering, little information remains readily available about it. By the 1980s, Emerson had dropped the TAT nomenclature from its marketing literature. It is likely that any overview of the line is incomplete. For Emerson itself, an end to an era came in 1990 when the company completely divested its Government and Defense Group division. It was spun off to form the ESCO Electronics Corporation. Emerson no longer lists armament products on its website.
TAT Origins: The TAT-101, TAT-103, and TAT-111
The first product in Emerson’s TAT line was the TAT-101, a turret featuring two 7.62mm M60C machine guns. The turret’s power supply and five hundred round ammunition magazine were external to the turret. The turret was flexible, allowing for elevation, depression, and left and right traverse, which could all be controlled by using a flexible sighting system like the one developed for Emerson’s M6 armament subsystem. A number of subvariants were produced. For instance, Emerson offered the TAT-101D turret for the UH-1D helicopter. This particular turret had seventy three degrees of traverse left or right and the guns could be elevated fifteen degrees and depressed forty-five degrees. It is unclear whether all TAT-101 turrets had the same flexibility specifications or whether it varied depending on the aircraft to which the turret was fitted.
The first notable application of the TAT-101 came in 1963 after Bell Helicopter had been awarded a contract to produce a proof of concept attack helicopter demonstrator. The resulting aircraft, the Bell Model 207 Sioux Scout, took elements of Bell’s earlier Model 47G and 47J Sioux aircraft, but coupled with a completely new front fuselage. This new front gave the helicopter a look that is now common to most dedicated attack helicopters, with its two-man crew seated in tandem, one behind the other, and a with the Emerson turret in the chin position.
The U.S. Army decided not to pursue the Sioux Scout, but it did pave the way for future attack helicopter development. Emerson subsequently offered variants of the TAT-101 to the U.S. military for the UH-1 series of helicopters, marketing the TAT-101D to the U.S. Army and the TAT-101E to the Marine Corps for their UH-1E. In addition, given the larger main cabin of the UH-1D, Emerson also offered the option of a second flexible sighting system mounted on a sliding track attached to the cabin roof for individuals situated in the rear of the helicopter.
The U.S. Army did not procure the TAT-101D turret, but the U.S. Marine Corps did procure the TAT-101E. The Marine Corps purchased a total of ninety-four TAT-101Es, beginning to modify the UH-1E to carry them in April 1967. Aircraft fitted with the turret were used by helicopter units in Vietnam. Marine Corps experience with the turret in the Southeast Asian environment was not positive. The turret was found to be fragile and sensitive to environmental factors. Though delivered with a protective cover, Marine aircrews often dispensed with it due to the need to conduct frequent repairs. Instead, when the aircraft was on the ground, the turret assembly was wrapped in some manner of protective covering. By April 1972, the TAT-101Es had been removed from all aircraft.
Emerson also sought foreign sales for the TAT-101 series. The Federal Republic of Germany (FRG) evaluated a variant of the TAT-101D in the 1960s for its UH-1D aircraft. The turret for the FRG was designated as the TAT-103 and differed from the basic TAT-101 turret only in that 7.62mm MG1 machine guns were substituted for the M60s on turrets offered to the U.S. military. Emerson had already marketed the TAT-101 as being able to readily accept various major 7.62mm machine guns in use by the North Atlantic Treaty Alliance, including the MG1 and FN MAG. The FRG had no better an experience with the system and decided against procuring the system for its UH-1D fleet, canceling the program in August 1972.
In addition to the TAT-101 and TAT-103 turrets, Emerson developed a derivative of the turret with smaller ammunition magazines inside the turret itself. This was designated as the TAT-111. Emerson also marketed the TAT-101 for naval applications.
Minigun TATs: The TAT-102 and TAT-112
Emerson’s second TAT offering, the TAT-102, was similar in basic design to the TAT-101, but instead of having two machine guns it was designed specifically for the General Electric Minigun. Like the TAT-101, the turret’s power supply and ammunition magazine were external to the turret was flexible allowing for elevation, depression, and left and right traverse linked to a flexible sighting system. As the Minigun was electrically driven, by controlling the amount of power to the gun, the weapon’s rate of fire could also be controlled. In the TAT-102, the weapon could be set to fire at either two thousand or four thousand rounds per minute.
The TAT-102 was notably the first chin turret used on Bell’s AH-1G Cobra, continuing the close cooperation between Bell and Emerson in armed helicopters. The AH-1G was an outgrowth of Bell’s Model 209, a private venture to develop a purpose built attack helicopter. The Army initially procured the AH-1G in 1966 as an interim solution as delays continued to hound the Advanced Aerial Fire Support System (AAFSS) program. The prototype Model 209 and the initial production AH-1Gs featured the TAT-102 turret (sometimes also referred to as the TAT-102A), along with an eight thousand round magazine. The TAT-102 was only viewed as an interim system and was seen as being limited with its single gun. It was quickly replaced by the TAT-141 on the AH-1G.
In addition to being used on the AH-1G, the TAT-102 was also used on U.S. Air Force and U.S. Navy helicopters. The Navy’s HH-2C Seasprite, a specially configured version of the helicopter for the combat search and rescue, was initially fitted with a TAT-102 turret – the TAT-102K – in the chin position. The turret was mounted to the left of the aircraft centerline under the co-pilot’s position. Like the TAT-101, the TAT-102K had reliability issues, but also simply affected the aircraft’s center of gravity and added considerable weight. In many cases the turrets were removed from HH-2Cs and the turret was not a feature on the follow-on HH-2D.
Perhaps more interestingly, Emerson offered versions of the TAT-102 turret that were more like gun pods that could be carried on an aircraft’s stores stations like standard aircraft ordnance. The pod contained the TAT-102 turret and an eight thousand round magazine. The U.S. Air Force procured a limited number of TAT-102Bs for use on their CH-3E and HH-3E Jolly Green Giant aircraft, while the U.S. Navy procured a limited number of TAT-102Cs for use on their HH-3A Sea King aircraft. On the CH-3E and HH-3E, TAT-102Bs would be mounted in lieu of the jettisonable fuel tanks normally carried. On the HH-3A, a TAT-103C could be carried on the stores stations on either side of the aircraft, normally used on Navy SH-3A aircraft to carry torpedoes or depth charges. The guns were aimed using flexible sighting systems mounted in the main cabin of both types of aircraft.
The use of the TAT-102B and TAT-102C was limited for many of the same reasons as the TAT-102K on the HH-2C. The added weight reduced mission endurance and aircraft maneuverability. Air Force pilots were reportedly unhappy to have to choose between weapons and fuel on CSAR missions, where running out of fuel could place both the aircraft’s crew and any potential survivors in additional danger. Pintle mounted weapons at the crew doors and the rear ramp were more popular defensive armament on Air Force CH-3Es and HH-3Es and Navy HH-3As.
Also, as with the TAT-101, Emerson developed a derivative of the turret with smaller ammunition magazines inside the turret itself. This was designated as the TAT-112.
Arming the AH-56A: The TAT-123, TAT-124, and TAT-132
Though it developed turrets for use on the Bell AH-1 series of helicopters, Emerson also developed the turrets for the Lockheed AH-56A Cheyenne, the helicopter selected for the Army’s AAFSS program. The AH-56A helicopter was designed to feature two turrets, one in the chin, and one under the center of the fuselage, which could rotate along with the gunner’s seat – the XM112 swiveling gunner’s station. Sighting could also be achieved using the XM110 helmet mounted sight or the XM114 reflex sight in the pilot’s position. To provide additional flexibility, AH-56As could be fitted with one of two different chin turrets as well.
The two chin turrets were the TAT-123 and TAT-124. The major difference between the two was the weapon mounted. The TAT-123 contained a single XM196 machine gun, a variant of the basic M134 Minigun specifically designed for the installation that differed from the basic gun in that it lacked a rate limiter. The TAT-124 contained a single 40mm M129 automatic grenade launcher. The TAT-123 was coupled with a magazine containing over eleven thousand rounds. The TAT-124 on the other hand had a magazine with only seven hundred and eighty rounds. The TAT-123 and TAT-124 turrets received the designations XM53 and XM51 respectively. The TAT-132 belly turret contained a 30mm XM140 automatic cannon and fed from a magazine with a capacity of two thousand and ten rounds. The TAT-132 received the designation XM52.
Cannon Armed: The TAT-136 and TAT-140
Not to be dissuaded from a less than enthusiastic response to the TAT-102B, Emerson proposed additional methods of up-gunning U.S. Air Force HH-3Es in the late 1960s. The first of these proposals simply involved the fitting of a TAT-102 turret to the underside of the aircraft’s rear cargo ramp. In flight, the ramp would be lowered to make the turret level with the underside of the fuselage and from there it could provide three hundred and sixty degree coverage. The weapon would be controlled from one of four sighting stations or from a master control station in the cockpit.
At the same time, Emerson also proposed the fitting of two turrets at the front of the sponsons on the left and right side of the CH-53A aircraft, which the Air Force was investigating as a replacement for the HH-3E in the CSAR role. These turrets, the TAT-136, could be fitted with larger automatic cannon and installed in the sponsons would provide over one hundred and eighty degrees of coverage on either side of the aircraft. According to Emerson, the TAT-136, which was also offered as an armament option for the AH-1G, could accommodate a 20mm Mk 12 Mod 0 cannon, a 20mm M24 cannon, or a 30mm XM140 cannon. The U.S. Air Force decided against both the TAT-102 ramp arrangement and the TAT-136 for use on the HH-3E and the HH-53B/C aircraft.
The TAT-136 was also not selected for the AH-1G, after which Emerson developed another turret for the AH-1G, specifically designed to provide a “universal” mount for a wide variety of weapons. Only one weapon could be fitted at any one time, but Emerson marketed the turret as being able to accommodate most machine guns and cannon in the U.S. arsenal from 7.62mm to 30mm. The TAT-140 was evaluated by the U.S. Army, after being passed over initially, fitted with the XM140 cannon and designated as the XM120. In the end, both the U.S. Army and the U.S. Marine Corps selected the General Electric universal turret fitted with the 20mm M197 cannon for their up-gunned AH-1 aircraft.
Arming the AH-1G: The TAT-141
In addition to the TAT-136 and TAT-140, Emerson also offered the TAT-141 as an option for additional firepower on the AH-1G. Unlike the TAT-136 and TAT-140, which were passed over, the TAT-141 became the standard armament for the AH-1G, receiving the designation M28. This turret was further refined and remained in use on the AH-1Q, AH-1S, and AH-1P Cobra helicopters, with the final variant being designated as the M28A3.
A significant improvement over the TAT-102, the TAT-141 allowed for the mounting of two M134 Miniguns, two M129 automatic grenade launchers, or one of each. The latter configuration became the most common. The weapons in the TAT-141 could be elevated twenty degrees and depressed fifty degrees, and the turret could be traversed one hundred and ten degrees to the left or right. The weapons fed from separate magazines, the type of which depended on which weapon was fitted in which position. Machine guns fed from four thousand round magazines, while grenade launchers fed from thirty round magazines.
M61A1 Turrets: The TAT-157 and TAT-161
Emerson’s TAT-157 and TAT-161 were both turrets for the General Electric M61A1 Vulcan cannon. There is some dispute about the turret nomenclatures, however. On 20 August 1968, the U.S. Air Force’s Air Staff directed Air Force Systems Command to mount an M61A1 cannon in place of the rotating bomb bay door on a B-57G Tropic Moon III aircraft as part of a project codenamed Pave Gat. This came after the demonstrated success of the M61A1 cannons mounted on the AC-130 gunship when attacking truck convoys. The gun would be linked to the onboard Low Light Level Television (LLLTV) and laser range finder on the Tropic Moon III aircraft.
A weapons pallet that combined a turret developed by Emerson, an ammunition magazine, and power supply was fabricated in early 1969. The pallet arrangement, which replaced the aircraft’s bomb bay door, allowed the system to be rapidly mounted and demounted without major modification to the aircraft. Emerson documentation says that the turret system used for the Pave Gat program was the TAT-157. Air Force documentation says that it was the TAT-161. Emerson documentation acknowledges both turrets and it could be that they were functionally identical, but the TAT nomenclatures only refer to the specific type of aircraft on which the turret was to be fitted. Emerson documentation says that it proposed the TAT-161 as yet another possible armament option for the AH-1 series of helicopters.
Regardless of the appropriate nomenclature, Pave Gat continued into 1970. In addition to the weapon’s pallet, the aircraft’s AN/AQX-5 weapon delivery system was modified by Westinghouse to aim the gun. Westinghouse was also the primary contractor in the integration of the gun system. By April 1970, after a number of flight tests, the system was proven to be feasible. At that time, Westinghouse proposed the Air Force procure two Pave Gat systems for evaluation. The Air Force agreed and proposed one aircraft be tested at Eglin Air Force Base in Florida and another prototype system be deployed for operational evaluation at Ubon Royal Thai Air Base in Thailand.
The first aircraft arrived at Eglin Air Force Base in January 1971 and began conducting testing and evaluation. During these flights, the aircraft also tested a special type of flechette ammunition, which was also being developed under Pave Gat. The arrowhead-shaped flechettes, made of dense metal, were specifically designed to do maximum damage to soft-skinned vehicles that would be the aircraft’s primary target. Delays affected the Pave Gat program and in August 1971 it was decided as part of the U.S. drawdown in Southeast Asia to return the deployed B-57Gs in Thailand to the United States. Despite the functional nature of the Pave Gat system, it was decided that an operational evaluation of less than ninety days would be insufficient time to glean any useful information. In addition, the AC-130 gunship had fully proven itself already and the requirement for a second system to fill a similar role was reduced. On 21 December 1971, the Pave Gat program was terminated.
TAT Cousins: The Mini-TAT and TAP-239
As mentioned, the Emerson TAT line gradually faded from view in the 1970s. Still, Emerson did market a small turret system for a period as the Mini-TAT. This system was designed to be mounted on almost any helicopter and was armed with a Minigun. The weapon was mounted so that while on the ground it would be folded under the aircraft in a stowed position. Once in flight, the weapon would be lowered and have a full three-hundred and sixty degrees of rotation below the helicopter.
The U.S. Army explored the Mini-TAT as part of the Modem Army Selected Systems Test, Evaluation and Review (MASSTER) as a possible weapon for scout helicopters. The system was also evaluated by the Canadians, who loaned some to the U.S. Air Force as part of the Joint Countering Attack Helicopters (J-CATCH) program, which sought to develop tactics to counter Soviet attack helicopters such as the Mi-24 Hind. Though it was not procured by the U.S. or the Canadians, Emerson continued to market the Mini-TAT. At least one sale was made to Oman, who mounted the system on Bell 206 helicopters. Emerson continued to offer the system into the 1980s, but having dispensed with the TAT nomenclature, relabeled the system as the Flexible Turret System (FTS).
Emerson also produced at least one traditional gun pod, the TAP-239, with TAP standing for Tactical Armament Pod. The TAP-239 contained a single 20mm M39 cannon, and was marketed again primarily for the AH-1 series of helicopters, though it could be mounted on any aircraft with the appropriate mounting hardware.
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