Westland Helicopters Limited

Gkn Westland Helicopters Limited

Westland Helicopter Limited

Westland Plc

Frederick J Perry

Alan Brocklehurst

Robert John Harrison

Mark A Crannage

Robert E Hansford

Nicholas C Isaacs

An aerofoil comprises a leading edge and a trailing edge which define a mean chord length, and the aerofoil having an inner or root end adapted for attachment to an aircraft, and an outer end which includes a tip which is adapted in use to divide the airflow into two generally equal vortices one being an inner vortex and the other being an outer vortex the inner vortex being arranged to trail from an outer edge of a forward region of the tip and pass over a rear region of the tip.

Aerofoil

A propeller (10a) comprising a plurality of propeller blades (9a) each having a root end (11a) attached to the central propeller disc or hub (12a), an intermediate portion (13a) extending from the root end (11a) and having a generally aerofoil cross section extending chordwise between a leading edge (14a) and a trailing edge (15a), and the blade (9a) having a tip (19) at an end of the intermediate portion (13a) remote from the root end (11a), the tip (19) having a leading edge portion (20) extending forwardly from a junction (21) with the leading edge (14a) of the intermediate portion (13a) thus to provide a discontinuity or notch (25) in the leading edge (14a) of the blade (9a) at the junction (21).

Propeller

A rotary blade includes a fixed boundary layer control device extending spanwise on a lower surface adjacent the trailing edge to improve the lift/thrust characteristics of the blade especially at positive incidence angles. It was discovered that expected detrimental effects at zero/negative incidence did not materialize and the reasons are identified. Such blades are particularly useful for helicopter sustaining and anti-torque rotors.

Rotary blades

In a helicopter rotor blade having a root end for attachment to a rotor head, a central portion of constant chord dimension and a tip portion having a chord dimension greater than that of the central portion, an outboard region of the central portion has a negative basic pitching moment coefficient, an inboard region of the central portion has a basic pitching moment coefficient more positive than that of the outboard region and the tip portion has a positive basic pitching moment coefficient.

Helicopter rotor blade with improved performance characteristics

Flow separation behind the notch region of a swept tip of a helicopter rotor blade is reduced by a plurality of boundary layer control vanes located adjacent a forwardly swept leading edge portion forming the notch region.

Helicopter rotor blades

A helicoper rotor blade includes at its outer end a tip vane having a mean chord length greater than fifty percent of a chord length of a blade central portion and a span length greater than fifty percent of the blade chord which in operation generates two approximately equal strength tip vortices to reduce an acoustic impulse and a resulting noise known as blade slap.

A flexible beam type helicopter rotor includes restraining means outboard of a snubber means and connected between the flexible beam and a torque tube to increase the stiffness of the rotor in the lead/lag plane as applied pitch is increased.

Helicopter rotors

The swept extreme tip edge of a helicopter rotor blade incorporates blade droop to reduce aerodynamic pitching moments caused by spanwise flow encountered in the fore and aft sectors of a rotor rotational disc during forward flight of a helicopter on which the blade is fitted.

An outboard region of a helicopter rotor blade of aerofoil cross section has a thickness to chord ratio not greater than twelve percent and an inboard region has a thickness to chord ratio greater than twelve percent. Preferably, the thickness to chord ratio of the inboard region is greater than eighteen percent and may increase towards the root end to about twenty four percent. The inboard region may extend outwardly to a position not exceeding sixty percent of an operating radius of the rotor blade.

Growing community of inventors

Yeovil, United Kingdom

Frederick J Perry