Sin-I Cheng, Princeton professor emeritus of mechanical and aerospace engineering, died Dec. 6, 2011. He was 89.

Born in China, Cheng graduated from Jiao Tong University in Shanghai in 1946 and in 1949 received a master’s degree from Michigan. In 1952, he earned a Ph.D. in aeronautical engineering from Princeton. After 41 years of teaching at Princeton, he retired in 1992. Cheng had become an expert in the stability of liquid propellant rocket engines when rockets frequently blew up in testing.

After Russia’s launch of Sputnik in 1957, Cheng’s theoretical understanding, given in a 1956 monograph, was important in enabling the United Ststes to send rockets successfully into space. Subsequently, Cheng made significant advances to fluid dynamics. As an industry consultant, he helped develop early designs for intercontinental ballistic missiles.

Cheng wrote more than 100 articles and book chapters in his field. Sau-Hai Lam *58, Princeton’s Wilsey Professor emeritus, recalls Cheng as “one who imparted not only the subject matter itself, but the beauty of the subject when he taught.”

Cheng is survived by Jean, his wife of 65 years; three children (including Andrew ’71); seven grandchildren (including Caroline ’06, Katherine ’09, and Matthew ’09); and two great-grandchildren. A son, Thomas ’74, died in 2008.

Graduate memorials are prepared by the APGA.

Graduate Class of 1952