Dr. Charles Stark Draper, 85, an engineer and physicist who was known as the father of inertial navigation and whose guidance system led the Apollo astronauts to the moon and back, died July 25 at a hospital in Cambridge, Mass., after a stroke.

Dr. Draper was a longtime professor of aeronautics and astronautics at the Massachusetts Institute of Technology. Work he did there with gyroscopic systems broke new ground in technology in areas ranging from gunsights on World War II battleships to inertial guidance systems for intercontinental ballistic missiles.

His skills helped bring this country into the era of pinpoint-accurate navigation. The inertial guidance systems he developed are used in virtually all submarines, airplanes and missiles today.

At the heart of his navigation systems are gyroscopes, spinning tops that require force to be pushed off their axis. By measuring the force on a group of gyroscopes while a vehicle is moving, engineers are able to measure which way the vehicle is moving and how far it has gone.

The MIT Instrumentation Laboratory, which he helped found in 1939, developed the Mark 14 gyroscopic gunsight for Navy shipboard antiaircraft weaponry during World War II. The Mark 14 enabled ships to concentrate accurate fire on enemy planes while navigating rough seas or maneuvering to avoid enemy shells.

The MIT laboratory later developed guidance systems for the Polaris, Poseidon and Trident I and Trident II missile submarines, as well as components for the Atlas and Titan rockets.

In 1961, Dr. Draper's laboratory was chosen to develop the Apollo guidance and navigation system. Though some questioned whether such a system could be built, it was perfected before NASA required it.

Dr. Draper was a 1965 recipient of the National Medal of Science. He was an honorary fellow of the American Institute of Aeronautics and Astronautics and was a member of the National Inventors Hall of Fame and the International Space Hall of Fame.

Dr. Draper was born in Windsor, Mo. He earned a bachelor's degree in psychology at Stanford University and then went to MIT, where he earned a bachelor's degree in electrochemical engineering and a doctorate in physics.

He joined the MIT faculty and founded the Instrument Laboratory in 1939. Over the years, he gained a reputation as a tinkerer and popular teacher who inspired students with a brilliant intellect, contagious enthusiasm and combative temper.

The temper was in evidence when he stepped down as director of the MIT laboratory in the early 1970s. Because of its work for the Defense Department, it had become a focal point for student protesters who opposed this country's policies in Vietnam in particular and the defense establishment in general.

Dr. Draper defended his and the laboratory's work and said that defense work was not only a right but an obligation of science. In 1973, the laboratory became independent of MIT and was renamed the Charles Stark Draper Laboratory.

Dr. Draper's survivors include his wife, three sons, one daughter and six grandchildren.

CHARLES K. POST,

53, a teacher and administrator in Prince George's County schools for 30 years, died of cancer July 26 at his home in Upper Marlboro.

Mr. Post was born in Shickshinny, Pa., and graduated from Lycoming College in Williamsport, Pa. He earned a master's degree in education administration at George Washington University.

In 1957, Mr. Post moved to the Washington area and went to work for the Prince George's schools. He began as a history and social studies teacher at Greenbelt Junior High. In the 1960s, he was a basketball and baseball coach at Bladensburg High and then a driver education teacher at Duval High in Glendale.

In 1968, he was named assistant principal at William Wirt Junior High in New Carrollton. From 1971 to 1978, he was principal of Lord Baltimore Middle School in Fort Washington, and from 1978 to 1981, he was principal of Greenbelt Junior High. From 1981 to 1986, he was assistant principal of Crossland High in Camp Springs.

At the time of his death, Mr. Post was on special assignment to Suitland High in connection with its conversion to a magnet school for the visual and performing arts.

Mr. Post was a member of the Prince George's County School Administrators Association and the Prince George's, Maryland and National Education associations. He also was a Mason.

His marriage to Margo Post ended in divorce.

Survivors include his wife, Judy Post of Upper Marlboro; three children by his first marriage, Charles, Tracy and Carla Post, all of Crofton; two stepchildren, Brett and Kelly Curtis, both of Upper Marlboro; his mother, Cereta Scott, and one brother, Irving Post, both of Shickshinny; one stepbrother, E. Gary Scott of Ebensburg, Pa., and one stepsister, Nancy McClure of Benton, Pa.

MARGARET ASHLEIGH PADGETT,

82, a lifelong area resident who was a member of McKendree United Methodist Church in Washington, died of cancer July 25 at her home in Washington.

Mrs. Padgett was a native of Alexandria and a graduate of Alexandria High School. She had been a keypunch operator with the Southern Railway in the mid-1920s.

Her husband, William Carl Padgett, died in 1969. Her survivors include two daughters, Jean Harpster and Joan McMannama, both of Hyattsville; four grandchildren and three great-grandchildren.

SOPHIE DANISH,

69, a resident of the Washington area since 1948 who had been active in cultural, professional and volunteer organizations, died of cancer July 23 at her home in Silver Spring.

She had been a trustee of the Maryland College of Art and Design in Silver Spring since 1985, and a docent at the Smithsonian Institution's National Museum of American Art since 1969. She served on the Montgomery County Board of the National Council of Jewish Women and the board of the women's auxiliary of the Montgomery County Medical Society.

Mrs. Danish was a 1966 chairperson of the Cancer Crusade of the Montgomery County chapter of the American Cancer Society. She had done volunteer and public relations work for the Community Psychiatric Clinic in Bethesda and the American Cancer Society.

She was born in Massachusetts.

Survivors include her husband, Dr. Abraham W. Danish of Silver Spring; three daughters, Barbara Danish of Brooklyn, N.Y., Judy Danish of Rockville, and Katherine Danish of Bethesda, and three sisters, Ethel Levinson of Philadelphia and Dorothy Gordon and Bella Oblas, both of Los Angeles.

LUVETA W. GRESHAM,

90, a teacher and administrator with the D.C. public school system for nearly 35 years before retiring in 1962 as assistant principal of Garnet-Patterson Junior High School, died of cancer July 24 at her home in Washington.

Mrs. Gresham was born in Lumberton, N.C., and moved here at an early age. She was a 1921 graduate of Howard University and earned a master's degree in history there in 1927.

She began her career with the D.C. schools in 1927 at Randall Junior High. She taught there until going to Garnet-Patterson as a history and geography teacher in 1948. She was named assistant principal of the school in 1952.

Mrs. Gresham was a member of St. Mary's Episcopal Church in Washington, the National Council of Social Studies, the Friends of the Kennedy Center, the D.C. League of Women Voters, the D.C. Retired Teachers Association and the Association for the Study of Negro Life In History. She also had been a member of the Brightwood Community and Northwest Boundary civic associations.

Her marriage to Lorenzo Gresham ended in divorce.

She leaves no immediate survivors.

LEONARD F. WILLIAMS,

65, a retired electrical engineer who had worked on space satellites and nuclear power, died of cancer July 25 at George Washington University Hospital.

Mr. Williams, a resident of Oxon Hill, was born in Maynard, Mass., and was raised in the Washington area. He graduated from Montgomery Blair High School and received a degree in electrical engineering from the University of Maryland.

He served in the Army after World War II.

He was a Navy Department electrical engineer at the Bureau of Ships, the David Taylor Model Basin at Carderock and, in the late 1950s, at the Naval Research Laboratory, where he worked on early space satellites.

In 1959, Mr. Williams joined the engineering staff at Goddard Space Flight Center and later transferred to the National Aeronautics and Space Administration in Washington. In 1964, he joined the nuclear power field office at Fort Belvoir. He retired in 1973 after 30 years of government service.

Survivors include his wife, Grace S. Williams of Oxon Hill; two daughters, Kathleen Williams of Greenbelt and Laurey Koehler of Silver Spring; one son, Andrew Williams of Laurel; one sister, Anna Michon of Cheshire, Conn., and two grandchildren.