Wallace D. Hayes

Who was Wallace D. Hayes?

Wallace D. Hayes was a professor of mechanical and aerospace engineering at Princeton University and one of the world's leading theoretical aerodynamicists, whose numerous and fundamental contributions to the theories of supersonic and hypersonic flow and wave motion strongly influenced the design of aircraft at supersonic speeds and missiles at hypersonic speeds. This greatly enhanced the development of supersonic flight and supersonic aircraft design.

In a series of publications beginning in 1947 with his Ph.D. thesis under Theodore von Kármán at the California Institute of Technology, he developed a theory of supersonic flow called the area rule which strongly influenced the design of high-speed aircraft. His work also provided the first understanding of the behavior of delta wing aircraft flying just above the speed of sound.

He followed his work in supersonic flow with groundbreaking studies in the late 1940s and early 1950s in hypersonic flow, which is considered to begin at about five times the speed of sound, or Mach 5. He developed the Hayes similitude principle, which enabled designers to take the results of one series of tests or calculations and apply them to the design of an entire family of similar configurations where neither tests nor detailed calculations are available. Many of his developments appeared in his book Hypersonic Flow Theory, co-written with Ronald Probstein and first published in 1959.