One of the most interesting aspects of the aeronautical endeavours of Henson and Stringfellow was their awareness of the impact of the aeroplane as part of an overall transport system. It is all too easy in the field of aeronautical engineering to become mesmerised by the engineering intricacies of what one is doing and so fail to see the vehicle as part of this overall system concept.

In many respects we have, I think, been able to avoid this inward thinking in the helicopter since its vertical flight capability has become intimately bound up with considerations of its operational duties.