Modern Aircraft Geometry: A Description of the Mathematical Method used at SAAB, Sweden, for Aircraft Dimensioning and Shape Determination

THE determination of the shape and position of the various constructional elements in an aircraft must be based on principles different from those used in the case of an ordinary machine such as, for example, a lathe. In the latter case, the position of the parts in relation to each other can be given by measurements to existing plane base surfaces and centre lines. In aircraft work, on the other hand, where such base surfaces and centre lines are lacking, an attempt was made from the beginning to work with certain imaginary base planes named according to their position in the aircraft, such as datum plane, plane of symmetry, wing datum plane, and so on. This was unsatisfactory, however, and now the conception of co‐ordinates forms the basis for dimensioning.