delta hinge

delta hinge (plural delta hinges)

1. (aeronautics) On rotorcraft, a hinge with its axis parallel to the rotor plane of rotation, which permits the rotor blades to flap.
   • 1954, Eugene K. Liberatore, Rotary Wing Aircraft Handbooks and History: Convertible aircraft, page 39:

     This could be varied to produce a delta hinge effect for equalizing lateral moments.

   • 1969, Federal Aviation Administration, General aviation inspection aids, page 22:

     Overtorque of the delta hinge bolt is reported to cause binding in the pitch change mechanism and failure of the tail rotor pitch change bearing.

   • 2003, Harold Skaarup, Ohio Warbird Survivors 2003: A Handbook on where to find them, →ISBN:

     The Kiowa has a two-bladed semi-rigid seesaw all metal main rotor and a two-bladed rigid delta hinge all metal tail rotor.

   • 2007, Phil Croucher, Professional Helicopter Pilot Studies, →ISBN:

     You can get the same effect by offsetting the pitch change horn at the root of the blade (notice that the tip of the horn is in line with the extended delta hinge line in the picture).

• alightened, tinglehead