In 1941 the United States Army Air Force decided to use secondary sources to boost aircraft production and the St. Louis Aircraft Corporation was contracted to design and build a prototype of both an eight-seat and fifteen-seat troop carrying glider.[1] In total with the St. Louis examples, eight prototypes were ordered from different aircraft manufacturers.
The model SL-5 eight seat glider was given the military designation CG-5[2] and the prototype designated XCG-5. Howard C. Blosom test flew the XCG-5 from Lambert Field in 1942.[3] It proved to have serious aerodynamic flaws and structural problems causing Dutch Roll at speed.[1] The heavier fifteen-seat glider (designated the XCG-6) was not built.[2]
The USAAF ordered the Waco CG-3 for the eight/nine seat requirement, although only 100 were built. The fifteen-seat requirement was met by the Waco CG-4 of which more than 13,000 were built.
