Why does the shuttle throttle on ascent?

John wrote:

That pictures seems to show a land launch from Launch Complex 25 at
Cape Canaveral Air Force Station, which might . . . I emphasize might
. . . suggest that the initial non vertical climb is how the vehicle
is designed to perform . . . interesting *S*

Blue skies




That's what I thought also.
This photo of another land launch, shows the same antenna in the
background, although this time the missile is ascending vertically:
http://www.bomb-shelter.net/images/s...ub_missile.jpg
You really want to see one starting at a angle, check this photo:
http://www.spacegatewaysupport.com/i...trident4sm.jpg
This one, on the other hand, seems to be going more vertical as it
climbs: http://www.sciprods.com/images/trident_ll_02m.jpg
I think I know what's going on here; If you are attacking a target
that's well under the missile's maximum range, you don't have to worry
about getting the optimal trajectory for low air drag, but can fire it
on a depressed trajectory so that it stays fairly low in altitude and
can get nearer its target before detection by enemy radar, making any
attempt to intercept it more difficult.
That's probably what the inclined launches are testing; they're trading
altitude and range for speed, and operating more like a field gun than a
howitzer.

Pat