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Hybrid composite flexbeam for a helicopter bearingless main rotor assembly

  • US 5,431,538 A
  • Filed: 07/01/1993
  • Issued: 07/11/1995
  • Est. Priority Date: 07/01/1993
  • Status: Expired due to Term
First Claim
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1. A hybrid composite flexbeam for a bearingless main rotor assembly, comprising:

  • a pitch region formed by a plurality of unidirectional fiberglass plies, a plurality of unidirectional fiberglass and graphite plies in interleaved combination, and a plurality of unidirectional graphite plies, said plurality of unidirectional graphite plies defining a cruciform configuration in cross section for said pitch region, and wherein said plurality of unidirectional fiberglass plies, said plurality of unidirectional fiberglass and graphite plies, and said plurality of unidirectional graphite plies extend from root to tip of said hybrid composite flexbeam;

    an inboard transition region comprised of unidirectional fiberglass plies in abutting relation with edges of said plurality of unidirectional graphite plies defining said cruciform configuration, said abutting unidirectional fiberglass plies extending inboardly to said root of said hybrid flexbeam;

    a second inboard tapered region formed by a plurality of unidirectional fiberglass and graphite plies of varying lengths internally interleaved in combination with said plurality of unidirectional fiberglass plies, said plurality of unidirectional fiberglass and graphite plies, said plurality of unidirectional graphite plies, and said plurality of abutting unidirectional fiberglass plies extending inboardly from said inboard transition region, said plurality of internally interleaved unidirectional fiberglass and graphite plies of varying lengths extending inboardly to said root of said hybrid composite flexbeam;

    a first inboard tapered region formed by a plurality of fiberglass and graphite cross plies of varying lengths internally interleaved in combination with said plurality of unidirectional fiberglass plies, said plurality of unidirectional fiberglass and graphite plies, said plurality of unidirectional graphite plies, said plurality of internally interleaved unidirectional fiberglass and graphite plies of varying lengths, and said plurality of abutting unidirectional fiberglass plies extending inboardly from said second inboard tapered region, said plurality of internally interleaved fiberglass and graphite cross plies of varying lengths extending inboardly to said root of said hybrid composite flexbeam;

    a hub attachment region formed by said plurality of unidirectional fiberglass plies, said plurality of unidirectional fiberglass and graphite plies, said plurality of unidirectional graphite plies, said plurality of internally interleaved unidirectional fiberglass and graphite plies of varying lengths, said plurality of internally interleaved fiberglass and graphite cross plies of varying lengths, and said plurality of abutting unidirectional fiberglass plies extending inboardly from said first inboard tapered region;

    an outboard transition region comprised of unidirectional fiberglass plies in abutting relation with edges of said plurality of unidirectional graphite plies defining said cruciform configuration, said abutting unidirectional fiberglass plies extending outboardly to said tip of said hybrid flexbeam;

    an outboard tapered region formed by a plurality of fiberglass and graphite cross plies and a plurality of unidirectional fiberglass plies of varying lengths interleaved in combination with said plurality of unidirectional fiberglass plies, said plurality of unidirectional fiberglass and graphite plies, said plurality of unidirectional graphite plies, and said plurality of abutting unidirectional fiberglass plies extending outboardly from said outboard transition region, said plurality of internally interleaved fiberglass and graphite cross plies and said plurality of internally interleaved unidirectional fiberglass plies of varying lengths extending outboardly to said tip of said hybrid composite flexbeam; and

    a torque tube, main rotor blade attachment region formed by said plurality of unidirectional fiberglass plies, said plurality of unidirectional fiberglass and graphite plies, said plurality of unidirectional graphite plies, said plurality of internally interleaved fiberglass and graphite cross plies and said plurality of internally interleaved unidirectional fiberglass plies of varying lengths, and said plurality of abutting unidirectional fiberglass plies extending outboardly from said outboard tapered region.

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