Axle Fairings.
Fig. 98.—Axle fairing.
It is now the practice to streamline the compression tubes between the vees of the undercarriage with a fairing of aluminium or three-ply. This is so arranged that in flight the axle lies in a slot formed in the fairing, which appreciably reduces head resistance. A typical arrangement is indicated by [Fig. 98]. The axle is usually formed of steel or duralumin tube, and in the majority of undercarriage arrangements is divided and hinged in the centre, a wire or wires from this point to the fuselage accounting for any strain. Duralumin tube is especially suited for this item, as a much stiffer axle is possible for a given weight, although, unfortunately, this is slightly discounted by the fact that duralumin does not form a good bearing surface for the wheel hubs, and it therefore becomes necessary to fit either sleeves or stub-axles of steel.