Much of the data published on the subject of cost prediction for aircraft has dealt with empirical methods of estimating the total engineering hours of design and development. Less seems to have been written by or for the practising estimator, concerned not only with the total estimate at the initial stages of the project but also with its continuous refinement to full go-ahead, on to certification and later still to variants. In this paper the authors describe some of the methods they use, the historical background against which the methods have evolved and discuss some of the problems which are met.

Over seven decades have passed since Wilbur and Orville Wright successfully flew their 1903 Flyer and thus ushered in a new era in human history. The impact on our own civilisation of the brothers' accomplishment has been as profound as it has been lasting.

As the new era of heavier-than-air flight matured and man gained increasing confidence in the air, his restless mind looked outward and pondered the possibility of flight into space. In due course, the intellectual and adventuresome descendants of the Wrights made tentative probings in latter day spacecraft counterparts of the 1903 Flyer and were soon spending days, weeks and even months in the strange extra-terrestrial environment.

Shorts’ experience in the world of so-called small airliners began with the design, development and manufacture of Sky van (Fig. 1), a 12 500 lb STOL transport aimed particularly at the expanding market provided by the developing nations. To date some 120 have been sold. The disposition of these aircraft around the world is shown at Fig. 2. Two competitive aircraft of roughly the same size and developed at the same time are the Canadian de Havilland Twin Otter and the American Beech 99, the former having captured by far the largest slice of the market.

With this background the Company has naturally retained a keen interest in the business prospects afforded by the third level airline market. Indeed, the prospect of maximising the non-recurring investment already made in Skyvan provided a spur both to continued project design and to market studies in that segment of the airline industry bounded by the Islander at one end and the DC-3 at the other—say 10 to 30 seats capacity.