Helicopter rotor and method of repairing same

Abstract

An aerofoil, particularly a helicopter main rotor blade has a leading edge protector comprising a strip of resilient polymer, preferably polyurethane, adhered to the leading edge of the blade.

Description

FIELD OF THE INVENTION[0001] The present invention relates to aerofoils, and more particularly to the protection of aerofoil leading edges from erosion damage. The invention has particular application to rotary wings, for example helicopter rotor blades.BACKGROUND[0002] The invention was developed in the environment of helicopter rotor blade repair, and will be described primarily in connection with that application. It will be understood by those knowledgeable in the art that the invention may have wider application to aerofoils for other purposes.[0003] The leading edges of helicopter rotor blades are subject to environmental wear, particularly when the helicopter is operated in harsh conditions, for example with significant quantities of ambient sand or salt. It has been found in particular that there is a recurring problem of skin erosion located inboard of the metal leading edge abrasion strips in main rotor blades. Current practice is to remove the blades from the helicopter a...

AI Technical Summary

Benefits of technology

[0008] The polymeric leading edge has been found to provide good resistance to erosion. It has been found to be particularly effective in the flex section of helicopter main rotor blades as the flexibility of the material limits any tendency to delaminate as occurs with rigid metal leading edge repairs in this section of the blade. On the other hand, it is to be noted that when used in the outboard flight section of a helicopter rotor, the high centrifugal forces on the polymer may cause creep of the material, leading to the polymer disengaging off the end of the blade. In consequence, the polymer leading edge is, in this environment, preferably limited to the flex section of the blade, with the flight section being equipped with a conventional metal leading edge.

[0009] Minor impact damage to a polymeric leading edge can readily be repaired in the field rather than dismounting the blade and shipping it away for repair, as would be the case with damage to a conventional leading edge.

[0010] According to another aspect of the present invention there is provided a method of protecting the leading edge of an aerofoil from erosion, comprising securing to the leading edge a layer of resilient polymeric material.

[0011] The installation of the polymeric leading edge is much more easily performed than the installation of a metal leading edge. It conforms more closely to the blade configuration since the metal edge is conventionally shaped using a brake, forming a sequence of substantially flat segments only approximating the smooth, uniform curvature of the original blade.

Problems solved by technology

On the other hand, it is to be noted that when used in the outboard flight section of a helicopter rotor, the high centrifugal forces on the polymer may cause creep of the material, leading to the polymer disengaging off the end of the blade.

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