There appears to have been a concerted USAF effort in the late 1940s to garner support by releasing drawings of aircraft projects that, while seemingly modern or exotic to the general public, were already obsolete or made irrelevant by the rush of technical development that was ongoing--and needed constant fiscal replenishment to continue in a time of budget cuts. The five images below were published in the September 13, 1948 issue of Aviation Week, and the style of the artwork seems to be very consistent with some of the images above.
The article is titled, "USAF 'Unveils' Speed Designs," with the sub-title of "From These Designs Came Today's Planes." If my surmize is correct, then they're likely to have been studies done by AMC's internal design staff as a means of 'QCing' vendor submissions, or perhaps to inspire vendors to pursue ideas that AMC found interesting. Image 1 was labeled "Refinement for F-80;" Image 2 was said to be "an early design...culminated in the [XF-87]" -- note the nose turret; Image 3 was a "Ramjet Fighter." Image 4 was "another redesign of the basic Lockheed F-80" but including JATO; image 5 was described as "an early product of joint Air Force-NACA high speed bomber project representing 1945 aerodynamic and tactical thinking--since vastly improved."