The Bell 207 Sioux Scout was a modified Bell 47 helicopter, developed by Bell Helicopter, under contract from the United States Army , as a proof-of-concept demonstrator for Bell's D-255 helicopter gunship design. The Sioux Scout featured a tandem cockpit, stub wings, and a chin-mounted gun turret.
Design and development
Bell Helicopter had been interested in the concept of a dedicated helicopter gunship since 1958. In June 1962, Bell displayed the mockup of its "D-255 Iroquois Warrior" to Army officials, hoping to solicit funding for further development. The D-255 was planned to be a purpose-built attack aircraft based on the UH-1B airframe and dynamic components with a new, slender airframe and a two-seat, tandem cockpit. It featured a grenade launcher in a ball turret on the nose, a 20 mm belly-mounted gun pod, and stub wings for mounting rockets or SS.10 anti-tank missiles.
The Army was interested and awarded Bell a proof of concept contract in December 1962. Bell added a new forward fuselage to Bell 47G-3 dynamic parts and Bell 47J center and rear fuselage to form an experimental helicopter named Model 207 Sioux Scout. The Sioux Scout included all the key features of a modern helicopter gunship – a tandem cockpit, stub wings for weapons, and a chin-mounted gun turret. The cockpit placed the gunner in the lower front seat and pilot in the rear. Both crew positions featured flight controls. For the gunner position, the gun sight and mount were located in the center, so side controls were fitted. The gunner controlled a chin-mounted gun turret with twin 7.62 mm (.308 in) M60 machine guns. The stub wings held external fuel tanks.
The Bell 207 first flew in July 1963. It had improved maneuverability over the Bell 47/OH-13 from which it was derived. The 207 was flight tested in 1963. Testing demonstrated increased high-speed turning ability due to the stub wings. Different wings, crowlings and tail surfaces were tested on the 207. At the end of 1963, the 207 was turned over to the Army pilots at Fort Benning, Georgia for further testing. After evaluating the Sioux Scout in early 1964, the Army was impressed, but also felt the Sioux Scout was undersized, underpowered, and generally not suited for practical use.
Later in 1964, the Army requested proposals for its Advanced Aerial Fire Support System (AAFSS). Bell proposed the D-262, a smaller version of the D-255 to make better use of the T53 engine from the UH-1. However, the Bell D-262 was not a selected as a finalist in the competition.
Length: 31.6 ft (9.63 m)
Rotor diameter: 37.2 ft (11.32 m)
Height: 9.28 ft (2.83)
Disc area: 1,085 ft² (m100.8 m²)
Empty weight : 1,893 lb (858 kg)
Max takeoff weight : 2,950 lb (1,340 kg)
Powerplant : 1 × Lycoming TVO-435-F1A Flat-6 piston engine, 280 hp (210 kW)
Maximum speed : 91 kt (105 mph, 169 km/h)
Cruise speed : 73 kt (84 mph, 135 km/h) at 5,000 ft (1,525 m)
Range : 214 nmi (245 miles, 395 km) at 6,000 ft (1,830 m)
Rate of climb : 860 ft/min (262 m/min)
Hover ceiling: 17,700 ft IGE ; 12,700 ft OGE (5,400 m IGE; 3900 m OGE)