Really love this paragraph on the Shuttle Training Aircraft wikipedia page.
To match the descent rate and drag profile of the real Shuttle at 37,000 feet (11,300 m), the main landing gear of the C-11A was lowered (the nose gear stayed retracted due to wind load constraints) and engine thrust was reversed. Its flaps could deflect upwards to decrease lift as well as downwards to increase lift.
Really drives home how you need to drag any normal airplane kicking and screaming into a regime where it’s as bad at staying in the air as the shuttle was :)