Bell 309 KingCobra
Bell announced the development of a new combat helicopter on 28 September 1971, derived from the Model 209 and 211, with company funds, with a 1.10m longer fuselage supporting a larger diameter rotor measuring 14.63m. Both the main and tail rotors had wider chord blades and the main rotor blades had double swept tips to reduce noise levels and improve performance at high speed. The nose was also modified to accept new apparatus, the available space for ammunition was increased, and the wing span was taken to 3.96m. A redesigned tail assembly was used with a lower fin for improved longitudinal stability. It also had the transmission, wide-chord two-blade main rotor and drive train of the Model 211 HueyTug. Design work was begun by a team led by Joe Tilley and construction started in January 1971.
Two prototypes of the Model 309 Kingcobra were built. The first (c/n 2503, registered N309J), which flew on 10 September 1971 at Fort Worth with Gene Colvin at the controls, was offered to the Marines with Turbo Twin Pack T400-CP-400 engines, while the second prototype (which flew in January 1972) was offered to the Army with a 2890shp Lycoming T55-L7C turbine of the Model 211, derated to 2050 on take-off.
The KingCobra incorporated new avionics and systems to fulfill its anti-tank mission (inertial navigation system, APN-198 radar altimeter, fire-control computer, multi-sensor sight, head-up display, helmet sighting system, FL-33 FLIR, low-light level television and, of course TOW guidance system). Armament included provision for sixteen TOW missiles under extended stub wings and a General Electric chin-turret housing a three-barelled 20mm Gatling gun with 1345 rounds.
On 11 April 1972, the first prototype was damaged in an accident. To meet future Army needs it was decided to convert the twin-engined 309 into single-engined configuration. As expected, on 9 August, 1972, the Army finally cancelled the Cheyenne programme and in due course two helicopter manufacturers, Sikorsky and Bell, submitted proposals for a less sophisticated aircraft, the Model S-67 and the Model 309 respectively. Tests and demonstrations were successfully conducted with both aircraft, but the Army set up new requirements and opened a new contest within the Advanced Attack Helicopter programme (AAH) which would eventually lead to the selection of the MDD/Hughes AH-64 Apache.
The Bell Model 309 (N309J) is now preserved by the US Army Aviation Museum in Fort Rucker, Alabama.
Bell 309 Kingcobra
Engine: 1 x Lycoming T55-L7C turboshaft, 2155kW
Main rotor diameter: 14.63m
Take-off weight: 4510kg
Empty weight: 2890kg
Gross weight: 6350kg
Max speed: 330km/h