V/STOL Aerodynamics

After 20 years of research, the western world has one operational V STOL aircraft and that is a military aircraft. An examination of the technical reasons for this failure to convert research results to hardware indicates that the penalties for VSTOL capability are still too large for most applications. This cost may be reduced by improved efficiency of the propulsive lift components and use of the newly emerging augmentor technology. Payload-weight ratios of VSTOL aircraft are 10 to 20 thus the productivity of the aircraft is very sensitive to small deficiencies or improvements in the various component efficiencies. The state of the art of some of these critical technological areas is reviewed. In particular, STOL augmentors, ground effects, and prediction methods are reviewed briefly. For VTOL, induced aerodynamics, vectoring devices, and modeling problems are reviewed. Research in these areas may significantly reduce the cost of VSTOL performance.