Some Stability Problems of Vertically Rising Aircraft

In recent years the reductions of weight, frontal area, and. bulk per horsepower of aircraft power plants have made it possible, and. probably economically feasible, to build. high-speed. aircraft which can take off and land. without forward speed. The Langley Laboratory of the NACA has been investigating the low speed and hovering stability and controllabi1ity of possibly suitable configurations for several years, in order to make available when needed adequate research information for the guidance of engineers and designers.