Why does the Shuttle turn on launch?
Date: Around 1993
I would like to know why the Shuttle, as soon as the launch
starts, turns around its vertical axis and assumes an oblique position and
I am not really sure, but here is one possibility. Missile
systems like this have to be guided into orbit. They must be lined up
properly in azimuth (angle) and then they need to be tilted over to eventually
become tangent to the earth and "inserted" into an orbit. The guidance
systems are sophisticated, but not so much that they can be driven. It is
very likely, for example, that the machine can only tilt in one direction,
like you and I. We can bend straight over from the waist. If we want to tilt
in another direction, we have to rotate on our vertical axis and then tilt.
This is what I think is going on with the shuttle. Why not orient the launch
tower so that they do not have to rotate? I assume it is because there is
more than one orbit that shuttles go into depending on the mission, so they
cannot line up the launch tower with more than one. It is easier to rotate
the missile than it is to rotate the launch tower. But this is just a guess
based on the way military missile systems work, or at least the way they used
to work. There may not be anyone on this network/system that is currently
working on the shuttle, but you could write to any NASA organization and I am
sure you will get the right answer, and perhaps a lot more information as
Up-date Spring 2010
According to NASA, the reasons are multiple. Primarily, they are...
1. It creates better line of sight ("look angles") for maintaining radio contact.
2. It creates better structural loading and allows heavier payloads.
3. It creates a simpler escape path in the case of an abort maneuver.
4. It allows the pilots a view of the horizon (helpful, but not mandatory).
5. The change in pitch during the roll points the craft in the right direction, since the shuttle needs to move mostly horizontally, not vertically (i.e., it only needs to go about 200 miles in about 8 minutes vertically, but during that same time must reach over 17,000 mph horizontally.
The stated reason that the shuttle does not launch *already* rotated is that they are using left-over launch pads from Apollo era which enforce a certain orientation.
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Update: June 2012