MIT Department of Electrical Engineering & Computer Science

MIT's Building 20: The Magical Incubator Story, Anecdote, or Reminiscence

DACL and the First Air-to-Air Missile Work

Robert Mann
rwmann@mit.edu

The Volume 9, Number 2, Fall 1997 "RLE undercurrents" features "A Last, Loving Look at an MIT Landmark -- Building 20" reinforced a flood of memories. I joined a research group there - the Dynamic Analysis and Control Laboratory which occupied Wing D - in July 1951 after conducting my combined SB-SM thesis with DACL Director, Professor John A. Hrones, who also was head of the Machine Design Division in the Mechanical Engineering Department.

The Lab's focus was on the as-yet-unrealized air-to-air missiles. We designed, fabricated and applied the world's largest and most sophisticated analog computer with a four-axis flight table on which were mounted the missile autopilot designs we were researching. The computer simulated the missile aerodynamics and control effects, which the flight table generating the accelerations the missile would therefore experience which, in turn, the autopilot would sense and input into the simulation.

The electrohydraulic valves to control the flight table were a major research effort in the Lab and our results, particularly in stabilizing such high-power, fast-response devices, made important contributions to the automatic control field.

I headed up the Design Division of the Lab, working on a variety of projects, but my focus (which became my Sc.D. thesis) was on internal power supplies for such missiles. My group conducted research on a range of alternate approaches but settled on solid-propellant powered, turboalternator systems. Professor David C. White supervised the electrical machinery studies. We delivered prototype hardware internal power unit to the Sperry Corporation for incorporation into their Sparrow I missile. Our most successful "product" was the design for Raytheon's Sparrow III missile, which like our other approaches, was tested in an iron box on the roof of Building 20 before delivery to Tom Phillips, then Project Director for Raytheon for Sparrow III. He was later CEO and Chairman of the Company. For several decades thereafter our Electrical Power Unit, U.S. Patent Number 3,230,381, powered all Sparrow III missiles and was adapted by Raytheon to the ground-to-air Hawk missile.

Professor Hrones resides in Florida and summers in Jaffrey, NH and was until recently on the MIT Alumni/ae Association Board. Professor S.Y. Lee, who was a principal in the hydraulic valve research, resides in Lexington, MA and I maintain an office in 3-137D, extension 3-2220.