The different features and characteristics of seven varieties of VTOL aircraft are defined and discussed. Basically, the future for all VTOL vehicles hinges on the recognition of the need to select the proper type for a specific role.
Particular areas discussed are lift efficiency, cruise efficiency, maximum speed and range, and hovering capability. The author notes that both speed and vertical or near-vertical capability are desirable features which bear a price. Compounding the two, he predicts very high cost for a highspeed VTOL. Thus the development of the low-speed helicopter necessarily emerged first.
Although the evolution of VTOL vehicles has been slow and difficult, progress continues toward the original goal of a safer more effective vehicle for transportation through the air.