Another tandem-rotor aircraft is the subject of today's history blog. The blog from the 3rd of July featured the Yak-24 helicopter, today we have a look at the Bristol Belvedere
The Bristol Belvedere (Type 192) is the result of a development process that saw several designs, the Type 173, Type 191 and Type 193. When these (Naval helicopter) projects were cancelled the Royal Air Force showed interest and the Type 192 Belevedere was created.
Three Type 191 fuselages were used for the development of the Type 192 as engine testbed and for fatigue tests.
The Naval heritage of the Type 192 gave some issues caused by the high forward undercarriage (designed like that for torpedo loading under the fuselage). This left the lower sill of the main door 4 ft (1.2 meters) of the ground. As the initial design was not intended as a troop carrier the engines were installed in the forward cabin and aft cabin.
Both rotors were interconnected with a drive shaft to avoid rotor blade collision and facilitate single-engine operation.
The single-engine operation was only available in the event of an emergency, in this configuration, the remaining engine would run up to a higher power output, to compensate for the loss of the other engine.
On the first flight, on this day in aviation history, of the Belvedere the aircraft was equipped with dual wooden rotor blades, the fifth prototype and subsequent aircraft were fitted with metal quadruple rotor blades.
Early production aircraft had a downward hinging passenger door, latter models had a sliding door as the rotor wash interfered with door operation on the hinging door.
Bristol 192 Belvedere XG464 serving with the RAF in Singapore
A total of 26 Belvedere helicopters would be produced as the Belvedere HC Mark 1 and used by the Royal Air Force. A civilian variant was also developed as the Type 192C as a 24 seat commuter helicopter. Although the speed record between London and Paris for helicop[ters was set with this variant in May 1961, no orders were made for the aircraft. The Belvedere set another speed record in June 1960 between London and Tripoli (Libia), with an average speed of 113 knots (130 mph or 209 kph). The relatively low design life of the Belvedere, only 1600 hours, resulted in a short operational life of the aircraft, and they were withdrawn from service in the spring of 1969, 8 years after entering active service. Some specifications for the Bristol Type 192 Belvedere:
Crew: 3
Capacity: 19 fully equipped troops or
12 stretchers with two seated wounded and a medical attendant[15] or
6,000 lb (2,700 kg) cargo (internal or slung)
Length: 54 ft 4 in (16.56 m)
Height: 17 ft 0 in (5.18 m)
Empty weight: 11,350 lb (5,148 kg)
Max takeoff weight: 19,000 lb (8,618 kg)
Powerplant: 2 × Napier Gazelle turboshaft, 1,465 shp (1,092 kW) each
Main rotor diameter: 2× 48 ft 11 in (14.91 m)
Cruise speed: 138 mph (222 km/h, 120 kn) (maximum)
Range: 460 mi (740 km, 400 nmi) (standard tankage)
Service ceiling: 12,000 ft (3,700 m)
Rate of climb: 850 ft/min (4.3 m/s)
Vertical climb rate: 440 ft/min (2.2 m/s)
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