Hacker News Reader

Comment by tempestn | Hacker News Reader

Can anyone point me to more information on this line from the article, regarding the space shuttle: "But the final design, modified to accommodate Air Force requirements, ended up being only a partially reusable launch system."?

What exactly were these "Air Force requirements"?

View on HN

There were several, but the two that stand out[1]:

1) The payload bay grew in size from 12 ft wide to 15 ft wide, in order to accommodate future unspecified military needs.

2) There were new cross-range requirements specified for reentry.[2] Basically, the military wanted to be able to launch satellites into polar orbits (useful for surveillance) and retain the capability to land after one orbit of the Earth. However, this meant that the Shuttle also needed to be able to -reach- the landing sites, which are normally not in the direct orbit path, but are divert 1000 miles away laterally (the cross part of cross-range).

[1] http://en.wikipedia.org/wiki/Space_Shuttle_design_process#Ai...

[2] http://yarchive.net/space/shuttle/shuttle_crossrange.html

In short: it needed to be capable of doing a once around polar orbit launch, which meant that when it came around back on the next orbit it would be several hundred miles away from the landing strip in Vandenberg. So it needed a huge cross range flight capability, which meant very large wings. Large wings meant more weight and a stronger airframe (also more weight), as well as a more complex and difficult thermal protection system. It raised the cost and complexity of the vehicle a great deal, though it wasn't the only reason why the Shuttle didn't meet its design goals.

And it never even flew that mission profile.

Reply on news.ycombinator.com