The C-140 JetStar was reconfigured as the General Purpose Airborne Simulator (GPAS) to simulate the flight characteristics of other aircraft. The JetStar was used for research for supersonic transports, general aviation aircraft, and as a training support aircraft for the Space Shuttle Approach and Landing tests at Dryden Flight Research Center (under different names) at Edwards, CA, in 1977. One of the engineers on the GPAS program was Ken Szalai, who later became Dryden's director from 1990 to August 1998.

The NASA C-140 JetStar research aircraft (top) is followed by a NASA Learjet equipped with acoustic sensors during one of several tests of advanced propellors mounted on the vertical pylon atop the JetStar's fuselage. Several advanced prop designs were tested on the JetStar in 1982 by NASA's Dryden Flight Research Facility (DFRF), Edwards, California, to study the effects of noise created by propellors on aircraft structures and cabin interiors. To assess possible noise problems with the subscale turbofan, DFRF technicians mounted microphones on both the JetStar and the Learjet chase plane. DFRF then made measurements at close range and at longer distances. The data enabled structural changes and flightpath modifications.