The Bell AH-1 Cobra or HueyCobra was the first real attack helicopter in the world, as before the AH-1 was operational only armed transport helicopters existed. Developed by Bell Helicopters, the AH-1 entered service in the 1960s.
The Vietnam War was the first time in that armed escort helicopters were needed. Helicopters were primarly used to carry soldiers and military equipmennt, but they were unable to protect themselves against enemies. Escort fighter aircraft couldn´t be used because they are to fast to remain close to the helicopters.
Bell Helicopters started working on Attack Helicopters in the 1950s, which were based on the Bell 47. In 1962 Bell showed a Mockup of the D-225 design to the US Army, whose interest in the concept led to the Model 207 Sioux Scout, which was first flown in July 1963. It was used in 1964 in a modified version ( D-262 ) for the Advanced Aerial Fire Support System (AAFSS). Despite losing the competition, Bell started developing the Model 209 in December 1964, which was first flown on 7th September 1965 and, because of the non-availability of the AH-56A from the AAFSS program, it seemed to be very useful. To save money, Bell used many parts of the Bell 204 UH-1C Iroqouis like the rotor, the engines and the transmission.
The new AH-1G received the nickname “Cobra“ by the US Army. To help the pilot target the weapons, the AH-1G is equipped with a M73 reflector sight. The AH-1G is only slightly armored, the pilot canopy was able to withstand weapons up to 7.62 mm calibre. In the Vientnam War Attack Helicopters got more and more important and because of the failed competitor, the Lockheed AH-56 Cheyenne, the Cobra was urgent for the US Army.
In August 1967, the first HueyCobras supported the US ground troops. During the Vietnam War, the US Army lost 157 HueyCobras due to SAMs and AA guns, plus another 12 due to enemy attacks on airbases, with another 109 lost because of accidents. The United States Marine Corps lost ten Cobras, but most of them were only lightly damaged and repaired after that. Primarly, the HueyCobras were used as flying Artillery, armed escort and reconnaissance. Later it was noticed that the Cobra doesn´t has enough firepower. And the unguided Hydra 70 missiles had the problem that only high skilled Army pilots were able to hit targets precisely, but the unskilled pilots could not shot that precisely. In night mission it was still possible to attack targets, but only if the targets were spotted by UH-1Y Hueys. But usually HueyCobras weren´t used in the night and in bad weather conditions.
After AH-1Gs were downed in Vietnam by SA-7 Surface to Air missiles, the US Army had to lower the IR signature of the AH-1Gs. On the engines a "sugar scoop" Engine exhaust diverter was mounted to lower the IR signature.
With the appearance of the AH-64 Apache the US Army replaced most of the AH-1F Cobras in the 1980s. Since the end of 2004 only the TAH-1S Surrogate is used by the Apache pilots to practise night missions. But the US Marines are still using the AH-1W SuperCobra, because they are perfect for the needs of the Marines and it is fitting for the Marines Amphibious vehicles ( not to large, slight, high firepower in comparison to size ).