The objective of design is the production of manufacturing drawings which are right. This objective will rarely be achieved without first making mistakes which require experiment to rectify so that design is the work of a team which includes designers who draw, development engineers and experimental manufacturing operatives.

Design must have an output which can be valued and the value of the output must exceed its costs. In the aircraft industry, the cost of design is a considerable part of the cost of the product and must be recovered directly from the customer. Because underestimating the cost of design is endemic and because some work done to obtain orders will not be successful, not all cost of design can be recovered from the customer and so some costs must be written off.