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Lockheed AH-56 Cheyenne

The History of the Lockheed AH-56 Cheyenne

The AH-56 Cheyenne is Lockheed's first and only foray into production helicopter development. In many ways, however, the Cheyenne is neither a true helicopter nor a true aircraftin many ways, today's tilt-rotor V-22 Osprey challenges traditional helicopter classifications. The performance specifications inherent in the design allow the Cheyenne system to reach unprecedented speeds unheard of for any type of helicopter before - or today. The system was originally conceived to escort fast-moving helicopter transport aircraft to bring troops into intense combat zones. As the AH-56 program grew, U.S.

Army senior personnel began to envision more roles for the already powerful AH-56. In the end, however, this dream still did not come true, as there were many obstacles on the way before Cheyenne was cancelled.

Location

By the mid-1950s, the concept of a gunship became popular among world military leaders. More than a decade ago, the Luftwaffe was able to field the first truly operational helicopter fleet, but in limited numbers. However, it did pave the way for other similar designs, and the US Army was no exception. Early attempts by the U.S.

Army simply added machine guns to existing transport helicopters as a measure of self-defense, although this was by no means an intended solution. The arrival of the turbo-powered Bell UH-1 "Huey" and the Vietnam War made the region think bigger, as these capable systems could be armed and perform well enough to keep up with the transport it was tasked with protecting . The UH-1 was eventually tested and equipped with various configurations of rocket pods, missiles, automatic grenade launchers, miniguns and machine guns.

The first UH-1 arrived in Southeast Asia in 1962.

While the UH-1 was able to keep up with its older transport counterparts, the arrival of the Boeing-Vertol CH-47 Chinook twin-engine transport series changed everything again. Chinooks can easily outrun their UH-1 brethren, rendering their armed escort partners seemingly useless where they need to fly over contested territory at sheer speed.

Because of this, the U.S. Army has begun developing a new program for specialized helicopter escorts capable of surviving low-altitude environments while covering areas ahead with fighter-like firepower.

Contributing to the AH-56's unique appearance, the empennage consists of a straight fuselage extension that contains the drive shafts for the twin tail rotors. The anti-torque four-blade rotor is located at the extreme edge of the horizontal stabilizer (extended to port) and rotates clockwise with the blades straight. Hamilton's standard three-blade "propeller" rotors were oriented aft, and it was this "propeller" propeller system that gave the Cheyenne a class-leading performance capability that no other helicopter system could match at the time. The thrust rotors are powered by the main driveline and fed through an idler shaft in the empennage to a gearbox located at the rear. The rotor system rotates counterclockwise.

Both the anti-torque and thrust systems are powered by the same powertrain and gearbox. The pitch of the thrust system is controlled by two crew members (pilot controls in both cockpits are redundant) via a rotary handle located on a common lever.

Cheyenne includes three internal self-sealing fuel tanks of 300, 78 and 60 gallons.

The Cheyenne has a downwardly swept vertical tail to which a single wheel semi-retractable tail gear is attached. The landing gear - including the tail wheel - is retractable to a certain extent, the main landing gear is semi-recessed under each sideboard, and the tail wheel disappears into the vertical tail.

Interestingly, the implementation of the landing gear kept Cheyenne's resting attitude largely horizontal when the aircraft was fully deployed. In contrast, the forward fuselage of the AH-65 Apache slopes upward.

Cheyenne is powered by a single powerplant from GE's family of turboshaft engines. One of the early engines was the T64-GE-16, initially rated at 3,425 shp. It was later increased to 3,925 shaft horsepower, and gear and rotor components were improved for more power and greater efficiency.

At the time of the ninth Cheyenne prototype, the T64-GE-716 was in service, delivering an impressive 4,275 shaft horsepower.

Cockpit

The gunner sits at the front of the double seating arrangement. Its position is dominated by the large base where the gun sights and controls are placed. In addition to the periscope sight, the base houses a right-handed pistol grip. Its dashboard consists of traditional and traditional dials, band gauges and large chart display plotters.

To the gunner's left is the collective, while to his right the loop is in a stowed position - this redundancy allows the gunner to take over the duties of the pilot if necessary. The gunner's seat is integrated into the fire control system - a system that rotates the seat horizontally in line with the orientation of the turret.

Interestingly, Cheyenne's early form leaves this forward cockpit area incomplete as the weapon system has not yet been added. Access to this cockpit via a hinged entry door on the starboard side is standard.

Grants the pilot a higher position to see the gunner's cockpit and beyond. In a way, this position is a more "simplified" arrangement, as there is no gunner's base system. The main dashboard is littered with various gauges, dials and system gauges.

Between the pilot's knees is the circulation control column as well as the graph display plotter. Above the map display is the weapon control. The joystick is on his left, while on his right is a grid of Cheyenne warning lights on the front panel. Access to this cockpit was standard on the starboard side of the late Cheyenne and could also be replaced by a hinged entry door and sunroof on earlier models.

Overall, Cheyenne's pilot and gunner got good visibility and clean lines in the cockpit.

Weapon Kit

As an attack helicopter, the AH-56 excels in ammunition capabilities. Cheyenne has a total of six mount pointstwo under each wing and two under the fuselage, just inside the ailerons. Each wing has an external and internal pylon position, and mission parameters can allow for mixing and matching of variable weapon loads. Each outboard mast can accommodate a 450-gallon drop tank or a 2.75-inch FFAR missile pod (1 x 7-round or 1 x 19-round pod).

The inner pylon also accepts 450 gallon drop tanks, 2.75" FFAR missile pods (1 x 19 round pod) or 3 x TOW anti-tank missiles (6 x TOW launchers total). An additional 300 gallon drop tank is supported, but not starboard. The US Army's official flight manual also shows that each hardpoint location alone can carry up to 2,000 lbs.

The outer wing pylons can also use triple adapter racks, up to a maximum of 20 per pylon Carrying three 2.75-inch FFAR 19-shot rocket pods makes Cheyenne even more impressive than it has been shown.

While external ammo is optional and can be mixed and matched as needed, Cheyenne also retains standard stationary weapons. The nose can be used as a platform to mount the XM-129 40mm air-cooled grenade launcher or the XM-196 7.62mm revolver machine gun. For the grenade launcher installation, Cheyenne can carry anti-personnel grenades up to 780x40mm and fire at a rate of 350 rounds per minute.

With the Minigun weapon, the count ends at 11,750 rounds of 7.62mm ammunition with a maximum rate of fire of 6,000 rounds per minute (though the gunner can also adjust in 750, 1,500 and 3,000 intervals.

Interestingly, Cheyenne's design uses a powered, belly-mounted turret system to complement the nose armament. The weapon attached to the system is the 30mm XM-140 cannon with 2,010 rounds of ammunition and a rate of fire of up to 450 rounds per minute.

This powered turret is mounted under the fuselage. Since Cheyenne has retractable landing gear, it makes sense to equip the platform with such an under-fuselage turret system to take full advantage of the available arc of fire against ground targets.

The turret can use a 200 degree lateral and +26/-60 degree up/down arc of fire, which means the AH-56 is safe without any potential ground targets.

Conclusion

While Cheyenne lost its edge as a viable weapon for the U.S. Army, the development and test results of its various systems played a major role in the success of its successor, the Hughes AH-64 Apache Tank Kill System. Additionally, many of Cheyenne's existing problems were reportedly resolved or about to be resolved when the axe fell on them. Despite their image of Cold War folly, we can still imagine systems like the AH-56 on the battlefield with all the advantages of a helicopter and the power of an aircraft.

Even today, the Cheyenne outperforms its closest rotorcraft competitor in performance alone. One can only imagine adding the tank-killing capabilities of the AH-64 to the design of the AH-56.

The U.S. Army is now learning many lessons as U.S. involvement in the Vietnam War wanes, and on August 17, 1972, a new competition emerged called the Advanced Attack Helicopter (AAH). This spawned Hughes' YAH-64, which eventually became the AH-64 Apache. While not a direct descendant of Cheyenne (nor a replacement for that question), she certainly incorporates many of the qualities that make Cheyenne such an amazing conceptexcept her top speed.

However, the Apache essentially replaced the Bell AH-1 Cobra and proved the cyclical nature of history. Unlike Cheyenne, the Apache is a helicopter.