Great! No one here understands the efficiency mismatch between the cooling ability of cryogenic fuel and its available capacity to cool superheated hypervelocity atmospheric gas (part) oxidiser (via an inert medium) across two thermal interfaces in a wingborne lifting body supporting the additional weight ( ie drag) of the industrial scale machinery necessary to achieve this process against, the efficiency of a booster loaded with pre prepared cryogenic fuel and oxidiser that requires only 150 sec to reach sub-orbital (nearly zero drag) space, in the competition to launch orbital payloads.
There may be applications for cryogenic fuel / atmospheric oxidiser engines and high-speed / very high altitude wingborne flight but, the efficient upward path to orbit is via the route of minimum time/drag as, I think, was illustrated by the Saturn V.
OAP