Very cool find!
Project SilverBug was actually a follow on to Project Winterhaven, which began in 1952. Project Winterhaven was originally started between the USAF
and Thomas Townsend Brown for the purpose of developing an antigravity driven saucer craft capable of transatmospheric flight in excess of Mach 3.
Although I am not positive, considering the specification of SilverBug to use turbine engines, and the resulting AVRO car, I would suggest that
SilverBug was designed as a diversion project, to take attention away from the main R&D project at Project Winterhaven.
