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| John Doe... |
 Posted: Sun Nov 01, 2009 4:06 pm |
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Derek Lyons wrote:
[quote]Correct. The idea is to fly away from the tower in order to reduce
the chance of wind induced collision, not to increase clearance
between the vehicle and the tower.
[/quote]
Why would the Shuttle not need such a manoeuver right at lightoff, but
Ares would need such a pronounced manoeuver ?
Since you can't move directly away from the tower (since thrust would
then be directed at the tower), is there really much of a point in
trying to deal with the wind for what, 2-3 seconds ?
Or is this necessary because the top end of the rocket, being wider,
offers greater wind pressure and thus acts as a lever pushing the top
end more than the lower end, and they must counter this immediatly ? |
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| Derek Lyons... |
| Posted: Sun Nov 01, 2009 10:49 pm |
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John Doe <jdoe at (no spam) doe.org> wrote:
[quote]Derek Lyons wrote:
Correct. The idea is to fly away from the tower in order to reduce
the chance of wind induced collision, not to increase clearance
between the vehicle and the tower.
Why would the Shuttle not need such a manoeuver right at lightoff, but
Ares would need such a pronounced manoeuver ?
[/quote]
The Shuttle is a) heavier, and b) has a lower finess ratio. It's not
as vulnerable.
D.
--
Touch-twice life. Eat. Drink. Laugh.
http://derekl1963.livejournal.com/
-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL |
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| Jorge R. Frank... |
| Posted: Mon Nov 02, 2009 12:14 am |
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Derek Lyons wrote:
[quote]John Doe <jdoe at (no spam) doe.org> wrote:
Derek Lyons wrote:
Correct. The idea is to fly away from the tower in order to reduce
the chance of wind induced collision, not to increase clearance
between the vehicle and the tower.
Why would the Shuttle not need such a manoeuver right at lightoff, but
Ares would need such a pronounced manoeuver ?
The Shuttle is a) heavier, and b) has a lower finess ratio. It's not
as vulnerable.
[/quote]
The shuttle also has lower limits on wind velocity at liftoff due to the
need to protect for abort landings. The low wind limits also contribute
to make a tower avoidance maneuver unnecessary for the shuttle. Ares I
is intended to have much looser wind limits, including winds toward the
pad, so it needs one, just like the Saturn V did.
If Ares I were restricted to the same wind limits as the shuttle, it
probably wouldn't need nearly as much of a tower avoidance maneuver (it
will still need at least a small one, since (as you say) it is much taller). |
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| Me... |
| Posted: Mon Nov 02, 2009 7:32 am |
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On Oct 31, 12:16 pm, David Spain <nos... at (no spam) 127.0.0.1> wrote:
[quote]Yes I was thinking that as well in another thread.
In another thread it was mentioned the possibility of 'sporadic afterburning'
as the booster burns out. Assuming this is a real phenomena of solids, would
it make more sense to initiate separation and ullage burn slightly before
SRB burnout when solid rocket performance is still stable?
Dave
[/quote]
No, because ullage rockets aren't hat high of thrust and the SRB would
run into the separating stage |
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| John Doe... |
| Posted: Wed Nov 04, 2009 1:20 am |
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For the initial seconds until the rocket has cleared the tower, could
they use thrusters in the upper levels of the rocket to compensate for
the wind instead of "leaning" the whole rocket into the wind ? |
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| Derek Lyons... |
| Posted: Wed Nov 04, 2009 11:34 am |
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John Doe <jdoe at (no spam) doe.org> wrote:
[quote]For the initial seconds until the rocket has cleared the tower, could
they use thrusters in the upper levels of the rocket to compensate for
the wind instead of "leaning" the whole rocket into the wind ?
[/quote]
No.
D.
--
Touch-twice life. Eat. Drink. Laugh.
http://derekl1963.livejournal.com/
-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL |
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| Me... |
| Posted: Fri Nov 06, 2009 8:47 am |
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Guest
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On Nov 4, 1:20 am, John Doe <j... at (no spam) doe.org> wrote:
[quote]For the initial seconds until the rocket has cleared the tower, could
they use thrusters in the upper levels of the rocket to compensate for
the wind instead of "leaning" the whole rocket into the wind ?
[/quote]
No, it is inefficient, more complicated and not needed. Also the
thrusters would make the vehicle react the same way. The vehicle is
going to rotate around its c.g. whether it is pushed from the top or
bottom |
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