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Lee Davenport and Radar

October 10, 2011

There's no question that technology won World War II for the Allies. As a consequence, modern wars are increasingly more technological. The US fights today with stealth aircraft, cruise missiles, unmanned aerial vehicles (UAVs), and numerous smaller innovations. Then there's the ultimate in armchair warfare, cyberwarfare.

The prime example of technological warfare in World War II is the Manhattan Project and its resultant invention, the atomic bomb, but there are others. As revealed in information declassified many years after the war, the British Bletchley Park cryptanalysis effort was an essential aid to the war effort. It was estimated that such cryptanalysis of the Enigma and Lorenz ciphers would have hastened the war's end by several years, were it not for the atomic bomb effort, a game-changer in any event.

Another important technology in World War II was radar. The most important invention of that period relating to radar was an improved cavity magnetron, created in 1940 by John Randall and Harry Boot. The magnetron was invented much earlier, but it was a low power device before Randall and Boot's improvements.

Randall and Boot were able to increase magnetron power a hundred-fold, thus making centimeter wavelength radar practical (3 GHz in frequency is 10 centimeters in wavelength). Such short wavelengths enabled detection of smaller objects, but their main advantage is that radar antennae could be reduced in size. This allowed radar installations on aircraft and smaller ships, and it also enabled mobile ground-based radar.

Wuerzburg radar installationAn example of non-centimetric radar.

The Würzburg Riese radar, operated by the Luftwaffe, at Douvres-la-Délivrande, Calvados, France. The antenna is almost 25 feet in diameter, necessitated by the 560 MHz operating frequency.

(Via Wikimedia Commons).

US radar research during World War II was centered around the MIT Radiation Laboratory. In this case, "radiation" referred to electromagnetic radiation. The radiation laboratory was able to build upon the technical advance of the magnetron. The first test of a centimetric radar system was performed from the rooftop of an MIT building, and the target, across the Charles River, was the spire of the Christian Science temple.

Success in that test was relayed to England via an unusual message in a shortwave broadcast, "We have seen Mary Baker Eddy with one eye," the one eye being the radar dish antenna.[1] Mary Baker Eddy was the founder of the Christian Science movement. This was followed by a successful test of an airborne radar set with a 30-inch parabolic antenna on March 27, 1941. One result of that test was the first airborne radar detection of a submarine.[2]

One major accomplishment of the Radiation Laboratory was the SCR-584 radar (Signal Corp Radio #584), a land-mobile radar that was designed to automatically direct anti-aircraft guns. It was the SCR-584 that enabled the shooting-down of about 85 percent of V-1 "buzz bombs" attacking London. Lee L. Davenport, who was a research fellow at the Radiation Laboratory in charge of SCR-584 development from 1941 through the end of World War II, died on September 30, 2011, at age 95.[3-5]

Lee Losee Davenport was born on December 31, 1915, in Schenectady, New York. His father, Harry, was a high school mathematics teacher. Davenport showed an early interest in electrical devices, building electric motors out of papers clips and copper wire,[4] something that I did also as a child.

Davenport received his bachelor's degree from Union College (Schenectady) in 1937, and a master's degree from the University of Pittsburgh in 1940.[3] He was a twenty-five-year-old graduate student working towards his Ph.D. at the University of Pittsburgh when he was invited to join the Radiation Laboratory.[5]

While at the Radiation Laboratory, Davenport was placed in charge of the SCR-584 program by physicist and laboratory deputy, Ivan Getting. The SCR-584 was a radar system designed to automatically track enemy aircraft and control anti-aircraft guns to shoot them down.[4]

In this capacity, he worked with General Electric, Westinghouse and Bell Laboratories to produce more than 3,000 SCR-584 radar sets for the war effort.[4] The general specifications of the SCR-584 appear in the table, below.

SCR-584 Technical Characteristics
Wavelength10 cm
Peak Power Output250 kW
Pulse Width0.8 microsecond
Pulse Repetition Frequency1707 per second
Antenna Diameter6 feet
Beam width to half power4 degrees
Range (Search)39.7 statute miles
Range (Auto-Track)18.2 statute miles
Gross Weight (K-78 trailer)10 short tons
Source: U.S. War Department Technical Manuals TM11-1324 and TM11-1524 (published April, 1946, by the US Government Printing Office), via Wikipedia.

The SCR-584 was technically superb, but it required experienced operators. Davenport discovered this to be a problem when he traveled to England to find that some gun crews did not know how to operate the radar. At one site, American soldiers were reading the radar manuals while buzz bombs flew overhead.[4]

Davenport, interviewed by Robert Buderi for his 1996 book, "The Invention That Changed the World: How a Small Group of Radar Pioneers Won the Second World War and Launched a Technological Revolution," recalled that "Seven or eight buzz bombs came within range while I was there... and the crew never got a single shot off at any one of them."[4]

Davenport was again in England two months before D-Day to waterproof the thirty-nine SCR-584 trailers destined to be put ashore at Normandy Beach to direct anti-aircraft fire. Davenport was one of the few people who knew the date of the planned D-Day invasion.[5]

Shortly after D-Day, Davenport found himself five miles behind the front lines, testing SCR-584 capability.[5] He carried papers that identified him as a captain in the Signal Corps in the event that he were captured.[4] SCR-584 radar sets were used also in the Pacific for the retaking of the Philippines.[4]

After the war, Davenport completed his Ph.D. in physics at the University of Pittsburgh. His dissertation was on the design of a radar-controlled missile, which was effectively the first guided missile.[3] He went on to Harvard University from 1946-1950 to lead construction of the second-largest (92-inch) cyclotron and to teach physics at Radcliffe College.[3,5]

After Harvard, Davenport became chief engineer for the B-47 bombsight at Perkin-Elmer Corporation (Stamford, CT). This bombsight incorporated an analog computer.[5] He became executive director of Perkin-Elmer, and then vice-president, director and chief engineer of Sylvania Corporation. He was named president of GTE Labs in 1962.[5]

Davenport survived a plane crash on July 2, 1963, and he gave congressional testimony about improving seat-belt safety in airplanes.[5] He was a member of the American Physical Society, and he was elected to membership in the National Academy of Engineering in 1973, cited for "original contributions to the development of radar, infrared analytical instrumentation, and leadership in development of communications technology."[7]

References:

  1. Philip J. Hilts, "Last Rites for a 'Plywood Palace' That Was a Rock of Science," The New York Times, March 31, 1998
  2. Greg Goebel, "Microwave Radar & The MIT Rad Lab," May 1, 2011.
  3. Anne W. Semmes, "Lee Davenport, researcher at the Radiation Laboratory during World War II, dies at 95," MIT Press Release, October 4, 2011.
  4. Richard Goldstein, "Lee Davenport Dies at 95; Developed Battlefront Radar," The New York Times, September 30, 2011.
  5. Frank MacEachern and Anne Semmes, "Lee Davenport, developer of anti-aircraft radar, dies at 95," Greenwich Time, October 4, 2011.
  6. Robert Buderi, "The Invention that Changed the World: How a Small Group of Radar Pioneers Won the Second World War and Launched a Technological Revolution," Touchstone, March 23, 1998, 576 pages (via Amazon).
  7. Dr. Lee L. Davenport, National Academy of Engineering Web Site.
  8. MIT Radiation Laboratory History Web Site.