This rocket-like plane could have been the SR-71 Blackbird replacement
The following image, published by Code One on its Facebook page, shows configuration SA-2S, an SR-71 Blackbird replacement concept that was studied by Convair in the early ’60s.
According to Code One, the rocket-like aircraft was designed to be 87.5 feet long and 16.7 feet tall. The wingspan was 35.0 feet and the wings swept for high-speed flight: wingspan was 60.3 feet with the wings extended for low-speed flight.
The aircraft had a takeoff weight of 92,000 pounds, a cruise speed of Mach 5 and 95,000 feet of ceiling; fuel weight was 37,600 pounds.
Several turbojets and booster rockets, some under development, were studied as alternative powerplants to improve performance.
Unfortunately, along with several other supersonic and hypersonic designs, SA-2S remained on the drawing board since the success of the Lockheed A-12 and SR-71 programs made alternatives unnecessary.