Breguet G.111
| G.111/G.11E | |
|---|---|
| |
| Breguet G.111 in flight | |
| Role | Experimental twin rotor helicopter |
| National origin | France |
| Manufacturer | Breguet Aviation |
| Designer | Louis Charles Breguet |
| First flight | 21 May 1949 |
| Number built | 1 |
The Breguet G.111 or alternatively, G.11E was a French passenger coaxial rotors helicopter flown soon after World War II. Only one was built, development ceasing when funding ran out.
Design and development[edit]
Louis Breguet designed his first helicopter, the Breguet-Richet Gyroplane, in 1908 but his 1935 Gyroplane Laboratoire was much more successful. It had no tail rotor but instead had co-axial contra-rotating rotors. After World War II Breguet was approached by the Société Francaises du Gyroplane (SFG, English: French Gyroplane Society) for a helicopter capable of carrying several passengers. Breguet developed his wartime studies of a project named the G.34 into the two-passenger Breguet G.11E, otherwise known as the Société Francaises du Gyroplane G.11E.[1]
Though a much larger aircraft, the G.11E used the same coaxial, three blade twin rotor layout as on the Gyroplane Laboratoire. It was initially powered by a fan cooled 179 kW (240 hp) Potez 9E nine cylinder radial engine mounted amidships, under the concentric rotor shafts. There was 6.5:1 speed reduction gearing between the engine and the rotor drive.[1][2] The rotors are built around tapered tube spars, which carry ribs and are Dural clad at the leading edges and with alloy over 3-ply elsewhere. They are mounted on flapping hinges and have drag hinge dampers. The control column alters cyclic pitch via a pair of swashplates and pedals make torque corrections and control yaw by changing the relative collective pitch of the two rotors. A mechanical inertial governor limited rotor accelerations; the pilot could increase the collective pitch over that set by the governor but not below it, emergencies apart.[2]
The G.11E's fuselage has a tapered, oval section. The forward part is a light alloy monocoque containing the well glazed cockpit, accessed by two sliding doors. The rear fuselage is a steel tube structure, covered in fabric, bearing a tall T-tail with a moving, one-piece tailplane which corrected the cyclic pitch via the control column to prevent once per revolution pitch oscillations. A wide track undercarriage has main wheels mounted on horizontal V-struts from the fuselage bottom and with a single bracing strut to the mid-fuselage on each side.[1][2]
The first flight was made on 21 May 1949 but tests showed that the G.11E was underpowered, so a decision was made to replace the Potez engine with a bigger nine-cylinder radial, a 336 kW (450 hp) Pratt & Whitney Wasp Junior. The type name was changed to G.111 and some re-design accompanied the power increase; the rotor diameter was increased by 1.00 m (3 ft 3 in) and the fuselage lengthened by 480 mm (1 ft 7 in) to include two more seats so that four passengers could be carried. Empty and maximum weights increased to 1,476 kg (3,254 lb) and 1,476 kg (3,254 lb) respectively.[1]
The G.111 began flight tests in 1951 but these were not completed as SFG were declared bankrupt the following year.
Variants[edit]
- G.11E
- Two passengers, Potez 9E engine.
- G.111
- Four passengers, G.11E re-engined with Wasp Junior, enlarged.
Specifications (G.11E)[edit]
Data from Gaillard (1991) p.91.[1]
General characteristics
- Crew: One pilot
- Capacity: Two passengers
- Length: 9.20 m (30 ft 2 in)
- Height: 4.05 m (13 ft 3 in)
- Empty weight: 850 kg (1,874 lb)
- Max takeoff weight: 1,300 kg (2,866 lb)
- Fuel capacity: 120 L (26.4 imp gal; 31.7 US gal)[2]
- Powerplant: 1 × Potez 9E-00 fan cooled[2] 9-cylinder radial, 180 kW (240 hp) [1][2]
- Main rotor diameter: 2 × 8.60 m (28 ft 3 in)
- Main rotor area: 58.0 m2 (624 sq ft) each. 3 blade rotors.
Performance
- Maximum speed: 240 km/h (150 mph, 130 kn)
- Cruise speed: 185 km/h (115 mph, 100 kn)
- Service ceiling: 4,000 m (13,000 ft)
See also[edit]
Related lists
References[edit]
