YF-12A in Flight Undergoing ‘Coldwall’ Heat Transfer ExperimentThe YF-12C was the second production SR-71A (61-7951), modified with YF-12A inlets and engines, and given a bogus tail number (06937).Read More Facebook Pinterest X LinkedIn Email https://www.nasa.gov/image-detail/yf-12a-flight-undergoing-coldwall-heat-transfer-experiment/Copy URL to clipboard> DownloadShareSize1041x718px