Geodetic Airframe - Aeroplanes

Aeroplanes

Barnes Wallis, inspired by his earlier experience with light alloy structures and the use of geodesically-arranged wiring to distribute the lifting loads of the gasbags in the design of the R100 airship, evolved the geodetic construction method (although it is commonly stated, there was no geodetic structure in R100). Wallis used the term "geodetic" to apply to the airframe and distinguish it from "geodesic" which is the proper term for a line on a curved surface, arising from geodesy.

The system was later used by Wallis's employer, Vickers-Armstrongs in a series of bomber aircraft, the Wellesley, Wellington, Warwick and Windsor. In these aircraft, the fuselage was built up from a number of duralumin alloy channel-beams that were formed into a large framework. Wooden battens were screwed onto the metal, to which the doped linen skin of the aircraft was fixed.

The metal lattice-work gave a light structure with tremendous strength; any one of the stringers could support some of the load from the opposite side of the aircraft. Blowing out the structure from one side would still leave the load-bearing structure as a whole intact. As a result, Wellingtons with huge areas of framework missing continued to return home when other types would not have survived; the dramatic effect enhanced by the doped fabric skin burning off, leaving the naked frames exposed (see photo). The benefits of the geodesic construction were partly offset by the difficulty of modifying the physical structure of the aircraft to allow for a change in length, profile, wingspan etc.