The Hypervelocity Impact Society is honoured to present its Distinguished Scientist Award to Dennis L. Orphal, or Denny as most of his friends call him.
Anyone working in the field of hypervelocity impact cannot but be aware of the work of Denny. He has published extensively on this topic for nearly 30 years, and has shown a keen desire to understand the varied phenomena that result from impact events in terms of the governing physics and materials science. In this pursuit he has made full use of both experiment and numerical simulations. He is one of the key proponents of the integrated approach and demonstrated his abilities in both disciplines. He has a flair for accurately applying experimental techniques, for example reverse ballistics, to obtain precise data for use in developing and validating analytic and numerical models to improve our understanding of the field. In this regard his hypervelocity impact work on ceramics is 'classic'.
A major part of this aspect of his research career, since 1978 in fact, has been concerned with Ballistic Missile Defence, something that is highly topical today. He has been extensively involved with the design and execution of many hypervelocity experiments. His very-high-obliquity experiments remain unique some 25 years later. He has undertaken basic research to investigate 'direct hit' missile defence concepts, which led to his conceiving and developing the kinetic energy kill enhancement devices used in two major Ballistic Missile Defense Office (BMDO) experimental programmes. He was a major contributor to the lethality analysis and testing for the THAAD (Theater High Altitude Area Defense) missile defence programmes and continues to support current programmes.
He has used his understanding of the field to make a significant contribution to the armour anti-armour research effort proposing a number of advanced penetrator concepts, notably segmented rods and extensible rod-tubes. His use of numerical modelling in conjunction with experimental data to understand the governing physics of the impact and penetration phenomenology in terms of simple ideas and material properties has been seminal. Together with James Walker he received a patent in 2002 for lightweight body armour; followed by another patent in 2004 (with Charlie Anderson and Gordon Johnson) on an innovative 'momentum trap' ballistic armor system.
Dennis graduated from Ohio Wesleyan University with a BA in physics in 1964, which was followed by three years at Los Alamos National Laboratory and then eight years at Computer Sciences Corporation, where he was able to complete his graduate studies at the University of Nevada in 1972. During this time he worked on the design of nuclear weapons and their effects including cratering, the seismic effects of underground tests and blast loading. In the following 30 years, at Physics International and then California Research & Technology (later purchased by Titan Corporation), Denny undertook his research in missile defence and hypervelocity impact. In 1996, Denny ''retired'' from