Charles Stark Draper

• Born: October 2, 1901
• Birthplace: Windsor, Missouri
• Died: July 25, 1987
• Place of death: Cambridge, Massachusetts

American aeronautical engineer

Draper is often referred to as the “father of inertial navigation.” His work with gyroscopes led to the development of the guidance computer for NASA’s Apollo program and improved gun sights for antiaircraft weapons.

Primary fields: Aeronautics and aerospace technology; military technology and weaponry

Primary inventions: Inertial navigation systems; Mark 14 gun sight

Early Life

Charles Stark Draper was born to Arthur and Martha Draper in Windsor, Missouri. His father was a dentist and his mother was a schoolteacher. In 1917, Draper enrolled in the University of Missouri, where he planned to study medicine. In 1919, he transferred to Stanford University in California, graduating in 1922 with a bachelor’s degree in psychology. He then attended Herald’s Radio College in order to work as a ship radio operator. After finishing his training, Draper took a road trip cross-country with a friend who was attending Harvard. On their way to Boston, they drove through Cambridge. Draper was taken with the town, especially the Massachusetts Institute of Technology (MIT). That day, he enrolled in MIT’s electrochemical program.

In 1926, Draper received his bachelor’s degree in electrochemical engineering. He stayed at MIT, studying mathematics, physics, chemistry, and aeronautics. Draper was given a nondepartmental master of science degree in 1928. He became an aeronautic engineering research assistant at MIT the following year. He continued taking a wide range of courses while working on his Ph.D. and became renowned for having the most credits of any MIT graduate student without a doctorate. MIT eventually pressured Draper to complete his degree. He finally finished his doctorate in 1938. He married Ivy Willard later that year.

Life’s Work

Draper became a professor at MIT in 1939. The college also put him in charge of its Instrumentation Laboratory, which now bears his name. His first project after taking over the MIT lab was to improve navigation by developing a new gyroscopic rate-of-turn indicator. The Sperry Gyroscope Company funded Draper’s research. Simply put, a gyroscope is a spinning wheel device that aids stability. Small gyroscopes, which resemble complex toy tops, are sold at educational and toy stores. Gyroscopes measure angular velocity—the amount of angular displacement (the difference in angle of the radius of the wheel over a time interval) divided by the total elapsed time. Angular velocity is measured in radians per second. Gyroscopes measure angular velocity in an inertial reference frame, a set of coordinates in space that is not accelerating. By knowing the initial orientation within the reference frame, and calculating in the angular velocity, it is possible to always know the system’s current orientation.

Draper was successful in creating more sensitive gyroscopic instruments, but they did not have practical applications until the beginning of World War II. Draper used his improved rate-of-turn indicator to develop the Mark 14 gun sight, which made antiaircraft fire from ships possible. The USS South Dakota was the first to use the device. In 1942, the ship successfully shot down thirty-two Japanese aircraft during the Battle of Santa Cruz. The Mark 14 gun sight was able to semiautomatically correct for wind, range, and ballistics using the ship’s deck as the inertial reference frame. The gun sight became popular with Allied forces; more than eighty-five thousand of the devices were installed on American and British vessels. Draper also worked on a gun sight for airplanes. Later models gave American pilots an advantage during the Korean War.

During the years following the end of World War II, Draper began working on an inertial navigation system (INS), which is used to determine the current position of a ship or plane based on the initial location and acceleration. Draper and his colleagues at MIT worked with the Air Force Armament Lab on the guidance system. Draper’s INS would be unaffected by enemy countermeasures or bad weather. He based his guidance system on the principles behind the Mark 14 gun sight, which used a gyroscope with only one direction of freedom; the gyroscope floated inside a viscous liquid. For the INS, Draper created a floating gyroscope accelerometer with three directions of freedom that measured position, velocity, and acceleration. His new accelerometer connected to an airplane’s instruments measuring direction and altitude, forming an inertial guidance system.

There was much debate within the scientific community about whether an INS would actually work. The most vocal critic was American physicist George Gamow. To prove his system worked, Draper set up a test flight in 1953. However, since it was a military program, it was not made public until 1957. Draper, seven other MIT engineers, and an Air Force crew flew from Bedford, Massachusetts, to Los Angeles. During the twelve-hour flight, no one touched the plane’s controls until they were ten miles from Los Angeles, to prepare for landing. The plane had successfully adjusted its altitude and speed on its own as it flew across country.

Draper also worked on designing a system for U.S. Navy ships and submarines. Draper’s Ships Inertial Navigation System (SINS) was not affected by the fact that over the course of months a ship’s gyroscopes tend to need recalibrating. Navy leaders funded Draper’s research, hoping to use it in nuclear submarines. They also asked him to develop a navigation system for ballistic missiles that would work in coordination with SINS. The systems were first installed in ships, planes, and submarines in 1956 and in ballistic missiles four years later.

In 1961, Draper and the other engineers at the instrumentation laboratory began working on guidance and control systems for the Apollo program of the National Aeronautics and Space Administration (NASA). Robert Seamans, deputy administrator of NASA, had taken the Weapons System Engineering course that Draper set up to educate civilian and military personnel about his INS. Seamans gave Draper the Apollo contract. It was Draper’s invention that successfully guided astronauts Neil Armstrong, Buzz Aldrin, and Michael Collins to the Moon in 1969 and brought them back safely.

During the late 1960’s, antiwar protests occurred often at MIT, mainly because of the lab’s strong military ties. MIT faculty and administration debated the effects the military funding was having on the college. In 1973, the lab was moved off MIT’s campus and renamed the Charles Stark Draper Laboratory.

Charles Draper died on July 25, 1987, in Cambridge. He and his wife had four children: James, Martha, Michael, and John. Draper was eighty-five.

Impact

Draper had a large impact on military and civilian life. The gun sight that he invented in the 1940’s gave U.S. Navy ships an advantage against enemy aircraft. Draper’s design also created a new field of research: aided tracking fire control. The Draper laboratory is among many groups working to improve the military’s “Dismounted Soldier” project, developing ways to fire missiles, drop bombs, and deliver supplies without putting pilots and flight crews at risk. The military’s Joint Precision Airdrop System (JPADS), which uses guided parachutes in resupply missions, was first used in combat in Afghanistan in 2006. The laboratory is also working on low-cost guidance systems for ballistic missiles. With these systems, the Navy would be able to fire long-range missiles in support of ground troops. The project has already increased the range and accuracy of two types of missiles used by the Navy.

Draper’s inertial guidance system was being installed on commercial airplanes by 1970. Draper also played a key role in the Apollo missions to the Moon. Newer versions of his system have been built for the space shuttle and International Space Station (ISS). When the ISS had problems with its onboard Russian computers in 2007, guidance control was maintained by Draper’s INS until the computers could be repaired. Future NASA missions, both manned and unmanned, will no doubt be equipped with versions of Draper’s inertial navigation system.

Bibliography

Hall, Eldon. Journey to the Moon: The History of the Apollo Guidance Computer. Reston, Va.: American Institute of Aeronautics and Astronautics, 1996. A history of the creation of the guidance computer used during the Apollo missions. The author shows how the Apollo program helped advance the semiconductor industry and the electronics revolution. Suitable for anyone interested in the history of computers or space exploration.

Johnson, Steven. The Secret of Apollo: Systems Management in American and European Space Programs. Baltimore: The Johns Hopkins University Press, 2006. A valuable resource for anyone interested in the space program, its business and management operations, or Cold War history.

Mackenzie, Donald. Inventing Accuracy: A Historical Sociology of Nuclear Missile Guidance. Cambridge, Mass.: MIT Press, 1990. Based on archival documents and interviews with those working in the field. The author discusses the relevant technology and explains it in a nonmathematical way. Focuses on social and historical contexts.