It is traditional in looking to the future to analyse past experience. In this paper the processes of development of 25 UK combat (or fighter-bomber) types covering a period of 45 years have been analysed and compared with available data on 20 US types.

In this analysis:

1. (i) Date of the project has been taken as date of Instruction to Proceed rather than the more usual first flight or entry into service dates, as it is felt that this more accurately represents technological projections involved.

2. (ii) Of necessity aircraft empty weight has been used as a basic parameter. While AMPR weight is more conventional in modern estimating, it is impossible to obtain such data for older types, but in a broad review such as this empty weight would seem to be an acceptable parameter.

3. (iii) Costs have been corrected to 1978 monetary values using curves deduced from cost of living and aerospace product data for both UK and USA.