In comparison with the previous papers, this one is somewhat speculative in tone. In discussing commercial VTOL there is little hard fact to form a sound basis for extrapolation as there is with conventional aviation.

But we do know that relatively fast VTOL aircraft can now be engineered around the jet, the fan and the propeller. It also seems that VTOL may offer some peculiar advantages and bring about a significant increase in the capacity of the air transport system as a whole.

So it should be useful now to discuss in pretty broad terms the impact of the higher performance type of VTOL on the system: it will certainly be invaluable to the aircraft constructor to try to find out the influence of the whole air transport environment upon the design of the vehicle itself.