THE DEEP STALL OF SAILPLANES - PART I

Abstract

Recently a couple of high performance sailplanes crashed in Australia. The cause of these crashes is suspected to be the deep stall - the malaise of every high "T" tail jet aircraft and a nightmare for every jet pilot, especially when flying an aircraft with an aft C.G. position. In the 1960's the deep stall was the cause of fatal crashes in the U.K. when the B.A.C. one eleven and the Trident prototypes crashed, killing large test crews. However, following various aerodynamic and electromechanical 'fixes' such as stick shakers and automatic stick pushers, the problem was supposedly 'put to bed' and conveniently forgotten. It was finally buttoned up by an excellent article by Peter Langford in 1965, the then assistant director general of D.C.A. Personally, I may not be able to explain the deep stall phenonenon as well as Mr. Langford, for the lack of time and space allotted to me with this article. Any reader wanting a deeper insight into this complex problern shoutd refer to Mr. Langfordr's article in 'Aircraft'.