For lack of a better term. Sometime between landing and mating with the jet that carries it back to Florida, a boxy structure is strapped to the back of the space shuttle, covering the engine nozzles.
What’s the purpose of this cover? The two that pop into my mind - protecting the nozzles/engines or reducing drag during the flight - strike me as slightly absurd. I can’t imagine that the hitched ride would put any significant stress on something that can withstand launching itself into space, and I’m pretty sure that if you strap one plane to the back of another, you’re going to have some crazy drag to begin with.
It’s actually more for this purpose than net reduction of drag. Even with this, the Shuttle Carrier Aircraft (SCA) only has a range of about 1,000 miles with the Orbiter on top, meaning it has to stop three times for a cross-country delivery. I believe there were plans to fit the aircraft for aerial refueling at one point but the cost of providing fueling services and the risk of a mid-air collision made it prohibitive.
Huh, I’d always just assumed it was a straight shot back, but that makes a lot of sense. Out of curiosity (since it seems you know something about it) does NASA have special training specifically for that? I mean, it must be incredibly different and much harder to fly that than a regular 747.
Yes, pilots for the SCA are specially trained to fly that aircraft, and the aircraft itself is extensively modified for this purpose. The original plan was to use a purpose designed ‘flying barge’ into which the Orbiter would fit, but the SCA turned out to be much cheaper and could be used for atmospheric flight tests. The C-5 Galaxy was also considered, but because it would have been an Air Force asset NASA would not have retained ownership and would have been at the mercy of the former for flight operations, whereas the 747 is a commercial airframe that has remained in production.
The information I have indicates that it was done primarily to protect the stabilizer (a significant problem) but no doubt it significantly reduces drag as well; those two effects are hand-in-hand, as the turbulence that would cause stabilizer problems would also substantially increase parasitic drag.
