Bell’s Cobra is the classic attack helicopter – and still going strong
Attack helicopters are now a key part of every advanced military’s order of battle, and their function has dictated their form so that most of them are built to a recognisable plan – a slim fuselage with two seats in tandem, a chin-mounted gun and stub wings for the main weapon load. Of course there are exceptions, like the Mi-24 HIND with its troop cabin or the Ka-52 with contra-rotating rotors and side by side seating, but most of the familiar designs – the AH-64 Apache, Eurocopter Tiger, Mi-28 HOKUM and newcomers like the Chinese WZ-10 and South Africa’s Rooivalk – all follow the same basic design. Where did that design come from, though? In fact the first attack helicopter of them all is still a major player in today’s market. It’s the Bell AH-1 Cobra.
Early in the Vietnam War the US Army realised that it needed close air support for its troops that could be in action minutes after it was requested. Unfortunately the US Air Force’s supporters in Congress won’t allow the Army to operate armed fixed-wing helicopters, so commanders were forced to ask the USAF every time ground units needed support. This often led to delays which cost lives, so the Army started looking at its fleet of helicopters to see if they could be used. In fact helicopters had been armed before, but now army aviation units took it a stage further. Standard door guns were replaced with fixed mounts for machineguns, first racks of M60s or a .50 Browning M2, then the lethally effective M134 minigun. Rocket pods were adapted to fit, loaded with 2.75″ high explosive and flechette rockets. These “gunship” helicopters were based on the famous UH-1 Huey utility helicopter, mostly older short-cabin UH-1B models that had been replaced as troop carriers by UH-1Ds. They worked reasonably well but they had drawbacks as combat helicopters; they were too large and didn’t have enough protection, so tended to take heavy losses even from small arms fire.
As early as 1962 the US Army decided to buy a purpose built attack helicopter, and their preference was for the AH-56 Cheyenne. This was a large, fast attack helicopter, but the design suffered endless problems. In the meantime Bell developed their own lighter design, based on the engine and drivetrain of the UH-1 installed in a new, slim fuselage with extensive armour for the crew and engine. At first the army wasn’t interested, but as the Cheyenne programme dragged on they gave the Bell 209 project – which was already flying successfully – another look. In April 1966 they ordered a first batch of 110, now called the AH-1, as an “interim” design until the AH-56 was ready. In 1972 the AH-56, still plagued with problems, was cancelled and the US Army went on to buy over a thousand AH-1s.
The AH-1 was produced in two main variants. The Army bought single-engined ones based on the drivetrain of the UH-1C. The US Marines were interested too, but as their helicopters need to make long flights over water they preferred the security of a twin-engined design. Bell obliged with the AH-1J, based on the twin-engined Bell 309 civilian variant of the Huey. The US Army replaced its AH-1Gs with Apaches years ago but the USMC, forbidden by Congress from buying the AH-64, has continued to upgrade them. The latest variant is the AH-1Z Viper, based on totally rebuilt airframes.
The Cobra design takes the proven mechanicals of the UH-1 or Bell 309 and fits them to a slim fuselage with two seats in an armoured cockpit. The pilot sits in the rear seat; the gunner is placed in front and slightly below to gain better visibility for his weapon sights. The Cobra’s basic armament is a chin-mounted gun turret which can mount a variety of weapons. The original Army ones had twin mounts, each of which could take either a 7.62mm minigun or a 40mm grenade launcher. When the AH-1J was being developed the Marines requested a heavier gun, capable of destroying light vehicles, and got a lightweight three-barrelled variant of the 20mm M61 cannon.
The main armament is carried on a pair of stub wings mounted on the fuselage. Each wing has two hardpoints, with the latest versions adding an additional AAM pylon on each wingtip. The early models used the wing hardpoints to carry 2.75″ rocket pods or gun pods fitted with additional miniguns or 20mm cannon. In 1973 the upgraded AH-1Q variant entered service; this could carry TOW anti-tank missiles on the wing pylons and was fitted with the required sight and guidance systems. Inspired by the Mi-24 HIND, this was the first western helicopter with a substantial anti-tank capability (the French Gazelle had already been fitted with SS-11 missiles, but was a much lighter design.)
Now the Cobra has been upgraded to launch the heavier Hellfire missile, and the AH-1Z can carry the Longbow guidance radar on a wing pylon. Modern electronics and uprated engines and rotors mean that the latest Cobra variants can still compete on equal terms with more modern designs. The Cobra is still in service with several nations, including Japan, Israel, Turkey and Pakistan, as well as the USMC. With the latest upgrades it’s likely it will be flying for many years yet. That’s not bad considering that 45 years ago it was an interim design.