Radiation Laboratory - Operations

Operations

The Radiation Laboratory officially opened in November 1940, using 4,000 square feet (370 m2) of space in MIT's Building 4, and under $500,000 initial funding from the NDRC. In addition to the Director, Lee DuBridge, I. I. Rabi was the deputy director for scientific matters and F. Wheeler Loomis (no relation to Alfred Loomis) the deputy director for administration. E. G. ("Taffy") Bowen was assigned as a representative of Great Britain.

Even before opening, the founders identified the first three projects for the Rad Lab. In the order of priority, these were (1) a 10-cm detection system (called Airborne Intercept or AI) for fighter aircraft, (2) a 10-cm gun-aiming system (called Gun Laying or GL) for anti-aircraft batteries, and (3) a long-range airborne radio navigation system.

To initiate the first two of these projects, the magnetron from Great Britain was used to build a 10-cm "breadboard" set; this was tested successfully from the rooftop of Building 4 in early January 1941. All members of the initial staff were involved in this endeavor.

Under Project 1 led by Edwin M. McMillan, an "engineered" set with an antenna using a 30-inch parabolic reflector followed. This, the first microwave radar built in America, was tested successfully in an aircraft on March 27, 1941. It was then taken to Great Britain by Taffy Bowen and tested in comparison with a 10-cm set being developed there.

For the final system, the Rad Lab staff combined features from their own and the British set. It eventually became the SCR-720, used extensively by both the U.S. Army Air Corps and the British Royal Air Force.

For Project 2, a 4-foot (later 6-foot) parabolic reflector on a pivoting mount was selected. Also, this set would use an electro-mechanical computer (called a Predictor-correlator) to keep the antenna aimed at an acquired target. Ivan A. Getting served as the project leader. Being much more complicated than the AI and required to be very rugged for field use, an engineered GL was not completed until December 1941. This eventually was fielded as the ubiquitous SCR-584, first gaining attention by directing the anti-aircraft fire that downed the about 85 percent of German V-1 flying bombs ("buzz bombs") attacking London.

Project 3, a long-range navigation system, was of particular interest to Great Britain. They had an existing hyperbolic-navigation system, called GEE, but it was inadequate, in both range and accuracy, to support aircraft during bombing runs on distant targets in Europe. When briefed by the Tizard Mission about GEE, Alfred Loomis personally conceptualized a new type of system that would overcome the deficiencies of GEE, and the development of his LORAN (an acronym for Long Range Navigation) was adopted as an initial project. The LORAN Division was established for the project and headed by Donald G. Fink. Operating in the Low Frequency (LF) portion of the radio spectrum, LORAN was the only non-microwave project of the Rad Lab. Incorporating major elements of GEE, LORAN was highly successful and beneficial to the war effort. By the end of hostilities, about 30 percent of the Earth's surface was covered by LORAN stations and used by 75,000 aircraft and surface vessels.

Following the Japanese Attack on Pearl Harbor and the entry of the U. S. into World War II, work at the Rad Lab greatly expanded. At the height of its activities, the Rad Lab employed nearly 4,000 people working in several countries. The Rad Lab had constructed, and was the initial occupant of, MIT's famous Building 20. Costing just over $1 million, this was one of the longest-surviving World War II temporary structures.

Activities eventually encompassed physical electronics, electromagnetic properties of matter, microwave physics, and microwave communication principles, and the Rad Lab made fundamental advances in all of these fields. Half of the radars deployed by the U. S. military during World War II were designed at the Rad Lab, including over 100 different microwave systems costing $1.5 billion. All of these sets improved considerably on pre-microwave, VHF systems from the Naval Research Laboratory and the Army's Signal Corps Laboratories, as well as British radars such as Robert Watson-Watt's Chain Home and Taffy Bowen's early airborne RDF sets.

Although the Rad Lab was initiated as a joint Anglo-American operation and many of its products were adopted by the British military, researchers in Great Britain continued with the development of microwave radar and, particularly with cooperation from Canada, produced many types of new systems. For the exchange of information, the Rad Lab established a branch operation in England and a number of British scientists and engineers worked on assignments at the Rad Lab.

The resonant-cavity magnetron continued to evolve at the Rad Lab. A team led by I. I. Rabi first extended the operation of the magnetron from 10-cm (called S-band), to 6-cm (C-band), then to 3-cm (X-band), and eventually to 1-cm (K-band). To keep pace, all of the other radar sub-systems also were evolving continuously. The Transmitter Division, under Albert G. Hill, eventually involved a staff of 800 persons in these efforts.

A radically different type of antenna for X-band systems was invented by Luis W. Alvarez and used in three new systems: an airborne mapping radar called Eagle, a blind-landing Ground Control Approach (GCA) system, and a ground-based Microwave Early-Warning (MEW) system. The latter two were highly successful and carried over into post-war applications. Eagle eventually was converted to a very effective mapping radar called H2X or Mickey and used by the U. S. Air Corps and Navy as well as the British RAF.

The most ambitious Rad Lab effort with long-term significance was Project Cadillac. Led by Jerome B. Wiesner, the project involved a high-power radar carried in a pod under a TBM Avenger aircraft and a Combat Information Center aboard an aircraft carrier. The objective was an airborne early warning and control system, providing the U. S. Navy with a surveillance capability to detect low-flying enemy aircraft at a range in excess of 100 miles (161 km). The project was initiated at a low level in mid-1942, but with the later advent of Japanese Kamikaze threats in the Pacific Theater of Operations, the work was greatly accelerated, eventually involving 20 percent of the Rad Lab staff. A prototype was flown in August 1944, and the system became operational early the next year. Although too late to affect the final war effort, the project laid the foundation for significant developments in the following years.

As the Rad Lab started, a laboratory was set up to develop electronic countermeasures (ECM), technologies to block enemy radars and communications. With Frederick E. Terman as director, this soon moved to the Harvard University campus (just a mile from MIT) and became the Radio Research Laboratory (RRL). Organizationally separate from the Rad Lab, but also under the OSRD, the two operations had much in common throughout their existences.