The compound helicopter — why have we not succeeded before?

Abstract

Abstract Compounding offers a way of advancing the performance of the standard helicopter significantly for a moderate increase in complexity through the addition of wings and/or auxiliary propulsion. The compound helicopter configuration has the potential advantages of increased speed, range, agility, productivity and reduced vibration levels over conventional helicopters. Despite several significant efforts, however, no compound helicopter has ever been put into production. This paper looks at three aircraft that came close to being accepted by operators and examines the reasons why they were not ultimately put into production. The cancellation of these projects appeared to be of a political nature rather than technical. Also addressed are the issues that still face prospective designers of compound helicopters and the lessons that can be extracted and applied to modern day efforts to build and sell an aircraft of this configuration.