Re: Columbia question (includes some general ascent profile questions)
- From: "John" <pelchat@xxxxxxxxxxx>
- Date: 22 Jun 2006 10:45:06 -0700
David Ball wrote:
On 22 Jun 2006 03:50:36 GMT, dg411@xxxxxxxxxxxxxxxxxxx (Andre Lieven)
wrote:
David Ball (davidbemail-1q04@xxxxxxxxxxxxxxxx) writes:
As I recall, the doomed Columbia flight was one that did NOT go to the
station. Now, I'm not an aerospace engineer, but this brings a
question to mind. Has there been any research into whether the ascent
profile/angle would have been different enough, if Colombia was going
to the station, for the foam to have missed the RCC panel if it came
off at that point (as determined by mission elapsed time or altitude
or speed or whatever is appropriate) in the flight?
In other words, was all this time spent fixing a problem that wouldn't
cause the loss of a shuttle if it happened on an ISS mission because
the different angle of wind flow at that point in the mission would
cause it to miss the RCC panels?
Hopefully this isn't a totally silly question.
Well... it is. The air doesn't care if you're flying north, west,
or north-west. It continues to flow past your craft the same way.
Having been a private pilot in my younger days (when I could still
pass the physical), I know what you mean, but we're talking about
different things. Air definitely cares about your crafts movement
relative to the air. Otherwise I wouldn't have had to practice things
like accelerated stalls and spin recovery.
Actually, what I was talking about was what you would call angle of
attack for an aircraft wing. Of course, the shuttle stack is not an
aircraft wing, but it does maneuver through the air at different
angles as necessary for the flight profile. Did the flight profile for
a different destination change the angle of air flow across the stack,
when the piece of foam came off, enough to make the foam hit the RCC
rather than scrape some tiles on the bottom or miss the shuttle
entirely.
That far into the ascent, does the stack always have a constant angle
relative to the air regardless of where it's headed?
Also, does the flight profile for a particular destination determine
how long it spends in lower, denser air during ascent, and does that
mean that some events, like exceeding mach one, take place in denser
air? I'm guessing that the answer to this might be yes unless all of
the maneuvering for orbital parameters takes place later in the
flight.
[snip]
Andre
-- David
David,
With all respect to Andre, I think you are right, certainly to some
extent. The STS stack does fly at different angles of attack during
ascent, especially near Max Q to reduce forces on the airframe
(spaceframe? *G*).
You can find a discussion regarding the issues surrounding the "low Q"
ascent being planned (low being a very relative term) at
http://www.nasaspaceflight.com/content/?id=4444.
While the low Q ascent was originally developed to deal with other
structural constraints that have since been dealt with, it has been
re-introduced specifically to reduce the loads on the ET, especially .
The article cites specific Q values that the stack would experience
flying the different profiles. The only thing I don't have going
back to your original post is what were the Q values seen during the
ascent of STS-107.
I am at the end of lunch at the moment, but I will try to find that
answer tonight.
Blue skies to all
John
.
- References:
- Columbia question
- From: David Ball
- Re: Columbia question
- From: Andre Lieven
- Re: Columbia question (includes some general ascent profile questions)
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