Percival P.74

Infobox Aircraft
name=P.74


caption= Hunting Percival P.74 being readied for flight testing c. 1956
type=Helicopter
manufacturer=Percival Aircraft Company
designer=
first flight=
introduced=
status=Cancelled 1956
primary user=
produced=
number built=1
unit cost=
developed from =
variants with their own articles=The Percival P.74 (later Hunting Percival P.74) was a British experimental helicopter designed in the 1950s that was based on the use of tip-jet powered rotors. Although innovative, the tip-rotor concept literally failed to get off the ground in the P.74, doomed by its inadequate power source. Rather than being modified, the P.74 was ignominiously towed off the airfield and scrapped. [ Winchester 2005, p. 230.]

Design and development

In 1951, a Helicopter Division was formed by Percival Aircraft Company and design work commenced on a medium-sized helicopter designated P.74. This experimental helicopter had a teardrop-shaped fuselage with a two-seat cockpit in the nose and a large cabin running the full length of the fuselage. Beneath the cabin floor were two Napier Oryx gas generators which fed compressed air to the tips of the three rotor blades through triple ejector ducts. The rotor blades used ailerons on the trailing edges with pitch control achieved by a screw jack. The unusual engine location necessitated exhaust pipes coming through the cabin wall between the rows of seats, creating an unenviable amount of din and heat for the intended passengers.

The P.74 prototype (designated the Hunting Percival P.74 after the company name change was instituted in 1954) was completed in the spring of 1956, and given the military serial number "XK889". The final product looked decidedly ungainly with the large bulbous fuselage tapering to a tiny "tailcone" that featured an equally tiny tail rotor (deemed sufficient for control since there was no torque from the tip-rotors). The undercarriage consisted of four wheels on splayed-out stubs with the front two wheels being castering.

Testing and evaluation

Ground testing in a static rig commenced in 1956 but the Oryx engines failed to develop full power and maximum gas flow. Even with modifications to the power units, the first flight was aborted when the P.74 failed to fly. This may have been providential as there were no escape provisions for the two pilots. Winchester 2005, p. 231.] The only entrance door was located at the rear on the port side. The primary test pilot was famously quoted as saying the hapless P.74 had "the cockpit, flying controls and engine controls... designed without any input from a pilot." Winchester 2005, p. 231.]

It was planned to fit a more powerful Rolls-Royce RB108 turbine and a further development of a ten-passenger (P.105) Winchester 2005, p. 231.] variant was on the "drawing boards" when the rationalisation of the helicopter industry later that year resulted in the P.74 project being cancelled and the prototype scrapped.

pecifications (P.74)

aircraft specifications

plane or copter?=copter
jet or prop?=prop

ref=
crew= 2
capacity= 8 passengers in two rows
length main=
length alt=
span main= 53 ft
span alt= 15.76 m
height main=
height alt=
area main=
area alt=
empty weight main=
empty weight alt=
loaded weight main=7,750 lb
loaded weight alt= 3,515 kg
max takeoff weight main= lb
max takeoff weight alt= kg

engine (prop)=Napier Oryx No. 1
type of prop= gas generator
number of props= 2
power main= 754 shp
power alt= 563 kW

max speed main= 110 mph (intended)
max speed alt= 177 km/h
range main=
range alt=
ceiling main=
ceiling alt=
climb rate main=
climb rate alt=
loading main=
loading alt=
power/mass main=
power/mass alt=

armament=

ee also

aircontent
related=
similar aircraft=
* Fairey Jet Gyrodyne (jet tipped rotor driven at takeoff and landing only)
* Hiller YH-32 Hornet

see also=
* Fairey Rotodyne

References

Notes

Bibliography

* Winchester, Jim. "The World's Worst Aircraft: From Pioneering Failures to Multimillion Dollar Disasters". London: Amber Books Ltd., 2005. ISBN 1-904687-34-2.

External links

* [http://avia.russian.ee/helicopters_eng/percival_p-74.php Hunting Percival P.74 1956]