Month in the Patent Office

An air brake 2 mounted on the lateral wall of an aircraft fuselage comprises a ledge 3 projecting from the working surface of the brake, and which lies parallel to the air flow when the brake is retracted, and produces a couple opposing the pitching couple which would be produced in the absence of the ledge, when the brake is extended, FIG. 1 shows the air brake 2 extended, where it would cause a diving couple. The airstream acts on the ledge 3 to produce a force R giving rise to an equal and opposite couple. The ledge is attached to the air brake through an angle iron to facilitate replacement of the ledge by another of dif‐ferent characteristics. The angular relationship of the air brake and ledge may be altered cither automatically in accordance with Mach number, or by the pilot.