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#420 by mkirk on 20 Jun, 2007 17:01
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Ikelos - 19/6/2007 8:16 PM
Yes but you can account for a 25 knot headwind just the same as a 35. Where do you draw the line and should it a definitive line? especially when the backup landing site is a lake bed that is over 10 miles long? It seems stupid to me that they would call off a landing at EDW for 26 knot winds.
Well I am not really sure how to respond to this, however, I DO know what the heck I am talking about here.
I was trying to keep my initial response short and to the point, if you need a better explanation then give me and some of the others in the forum some time and we can formulate more detailed responses.QuoteIt seems stupid to me that they would call off a landing at EDW for 26 knot winds.
Well generally that is exactly what would happen if the winds are out of limits – there would be a wave-off. What would be stupid is to ignore a well reasoned flight rule.
While the flight rules are not written in stone, working outside of the operational framework that they provide is not a decision that is made lightly.
The flight rules were developed to “outline preplanned decisions designed to minimize the amount of real-time rationalization required when non-nominal situations occur” during a mission. A lot of study and analysis went into the landing weather criteria, so when real world conditions are outside of what is considered to be the well understood limits of the orbiter the correct response is to step back.QuoteWhere do you draw the line and should it a definitive line?
Well for the headwind the line is less than or equal to 25 knots.QuoteYes but you can account for a 25 knot headwind just the same as a 35.
How? Not without changing the landing geometry (i.e. outer 20/18 degree and inner 1.5 degree glideslopes).
I will try and find some material that explains the rationale and assumptions used in flying the TAEM (terminal area energy management) approach in the shuttle.
Mark Kirkman
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#421 by Ikelos on 20 Jun, 2007 17:08
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Thanks for the response.
I fully understand the need for limits and waving off if they are borken to reduce the decision making time, but I am interested in seeing what makes that limit exactly 25 knots and not 26 knots or 27 knots... -
#422 by mkirk on 20 Jun, 2007 17:15
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Ikelos - 20/6/2007 12:08 PM
Thanks for the response.
I fully understand the need for limits and waving off if they are borken to reduce the decision making time, but I am interested in seeing what makes that limit exactly 25 knots and not 26 knots or 27 knots...
For the headwind it is all about managing energy.
I will see if I can dig out my notes on this and come up with a good overview. It may not be until after landing day due to my schedule.
Mark Kirkman -
#423 by JWag on 20 Jun, 2007 19:20
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I've read these three Q&A threads fairly carefully, and own two editions of Dennis Jenkins' Space Shuttle book.
However, I haven't seen anywhere that describes how the aft compartment access doors between the OMS pods and the wing upper surface got their name. From a thread elsewhere I learned (correctly?) that the left door is the "50-1" door, and the right side door is called "50-2". How'd they get their names?
I don't clearly remember anyone saying them aloud, and I pronounce "50-1" as "fifty-to-one" in my head. The word "dash" seems to have gone out of favor in aerospace circles.
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#424 by Jim on 20 Jun, 2007 20:44
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frame numbers I believe
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#425 by Namechange User on 20 Jun, 2007 22:06
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MondoMor - 20/6/2007 2:20 PM
I've read these three Q&A threads fairly carefully, and own two editions of Dennis Jenkins' Space Shuttle book.
However, I haven't seen anywhere that describes how the aft compartment access doors between the OMS pods and the wing upper surface got their name. From a thread elsewhere I learned (correctly?) that the left door is the "50-1" door, and the right side door is called "50-2". How'd they get their names?
I don't clearly remember anyone saying them aloud, and I pronounce "50-1" as "fifty-to-one" in my head. The word "dash" seems to have gone out of favor in aerospace circles.
The orbiter is devided into zones so that things can be easily referenced. The aft compartment is zone 50. Hence, the way to get in the aft is via the two doors, 50-1 and 50-2. -
#426 by Namechange User on 20 Jun, 2007 22:10
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The doors are called out as "fifty dash one" and "fifty dash two" as well
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#427 by Ikelos on 20 Jun, 2007 23:51
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Yes but the shuttle is flying relative to the air which will still be the exact same speed and the same L/D as if there was 0 wind, the only difference is the ground speed which can be accounted for by a split second delayed deorbit or a delayed entry into the glide slope to make your aiming point a little bit further down the runway so that as you descend, the wind will push you so that you touch down right on the numbers. And about sudden headwind increases: then maybe there should be a limit on how much the difference between the wind and the peak wind can be (a max gust wind difference limit)?
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#428 by brahmanknight on 20 Jun, 2007 23:54
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I have heard it mentioned that if a hurricane were to threaten Houston ( such as Hurricane Rita a few years ago ), that MCC would have to be evacuated. And if this were to occur, that a shuttle in orbit would have to come back to earth no matter what. Is this true? Is there really not back up plan in that respect?
And what about ISS? Would it have to be abandoned in the same scenario, or would Moscow take over? -
#429 by DaveS on 21 Jun, 2007 00:00
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brahmanknight - 21/6/2007 1:54 AM
Shuttle: Would be an early ticket home no matter what. The Firing Rooms in the Launch Control Center at KSC can handle a shuttle mission from the de-orbit point without any MCC assistance, but they cannot handle a full shuttle mission.
I have heard it mentioned that if a hurricane were to threaten Houston ( such as Hurricane Rita a few years ago ), that MCC would have to be evacuated. And if this were to occur, that a shuttle in orbit would have to come back to earth no matter what. Is this true? Is there really not back up plan in that respect?
And what about ISS? Would it have to be abandoned in the same scenario, or would Moscow take over?
ISS: Yes, Moscow is then in charge and the US solar arrays are feathered.
Go through the STS-115 prelaunch threads for more info when hurricane Ernesto looked like it was heading directly for the Houston-area. -
#430 by Namechange User on 21 Jun, 2007 00:16
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DaveS - 20/6/2007 7:00 PM
Quotebrahmanknight - 21/6/2007 1:54 AM
Shuttle: Would be an early ticket home no matter what. The Firing Rooms in the Launch Control Center at KSC can handle a shuttle mission from the de-orbit point without any MCC assistance, but they cannot handle a full shuttle mission.
I have heard it mentioned that if a hurricane were to threaten Houston ( such as Hurricane Rita a few years ago ), that MCC would have to be evacuated. And if this were to occur, that a shuttle in orbit would have to come back to earth no matter what. Is this true? Is there really not back up plan in that respect?
And what about ISS? Would it have to be abandoned in the same scenario, or would Moscow take over?
ISS: Yes, Moscow is then in charge and the US solar arrays are feathered.
Go through the STS-115 prelaunch threads for more info when hurricane Ernesto looked like it was heading directly for the Houston-area.
Actually the firing rooms at KSC can handle it. It's the exact same data feed. In the event of a hurricane, we would not say come home now. Take this mission, what if the crew was right in the middle of installing the array? We wouldn't say stop and we'll come back and finish later. -
#431 by gispa on 21 Jun, 2007 08:20
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I have a question about reentry procedure: in the normal operations the pilots in the space shuttle performes te reentry automaticly? and which is the point where they take the manual control of the spacecraft? thank you.
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#432 by Rocket Ronnie on 21 Jun, 2007 08:24
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gispa - 21/6/2007 3:20 AM
I have a question about reentry procedure: in the normal operations the pilots in the space shuttle performes te reentry automaticly? and which is the point where they take the manual control of the spacecraft? thank you.
There's only one pilot, but the orbiter does all the flying herself. The pilot does some flying in the final minute or so and they drop the gear etc. but it's mainly the orbiter all the time. -
#433 by rfoshaug on 21 Jun, 2007 09:17
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Why do all shuttle landings from ISS inclination always approach the Cape from the south? I mean, it's probably a desire to avoid flying over land as much as possible (especially after STS-107), but for Edwards it shouldn't make much of a difference if they came in from southwest or northwest? And it would give them twice as many landing opportunities every day.
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#434 by whitewatcher on 21 Jun, 2007 09:32
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rfoshaug - 21/6/2007 11:17 AM
Why do all shuttle landings from ISS inclination always approach the Cape from the south? I mean, it's probably a desire to avoid flying over land as much as possible (especially after STS-107), but for Edwards it shouldn't make much of a difference if they came in from southwest or northwest? And it would give them twice as many landing opportunities every day.
I guess that the TACAN (similar to VOR/DME) guidance system is only installed on one end of the runway.
It's not easy to land with the shuttle delta wings because you have no flaps and your angle of attack is pretty high, so you can't see to much of the runway. So you rely on a radio landing aids. -
#435 by psloss on 21 Jun, 2007 09:49
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rfoshaug - 21/6/2007 5:17 AM
Because they pretty much re-enter on ascending node orbits -- discussed a little bit in the current mission's FD8/9 thread:
Why do all shuttle landings from ISS inclination always approach the Cape from the south? I mean, it's probably a desire to avoid flying over land as much as possible (especially after STS-107), but for Edwards it shouldn't make much of a difference if they came in from southwest or northwest? And it would give them twice as many landing opportunities every day.
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=8406&posts=85&mid=151127&highlight=descending+node&highlightmode=2&action=search#M151127
(Earlier in the program, even some high-inclination missions re-entered on descending nodes.)
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#436 by rfoshaug on 21 Jun, 2007 10:47
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Thanks. Especially that bit about noctilucent clouds and ice crystals was interesting.
whitewatcher,
It is true that they rely on landing aids, but this is installed on both ends of the runway (often they make the final decision on which runway to use during the reentry based on wind directions). Once the orbiter is directly above the runway, it doesn't really matter if you turn about 270° left or about 270° right to align with the runway of choice, no matter if the reentry sees the shuttle approaching from northwest or southwest. -
#437 by psloss on 21 Jun, 2007 11:07
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rfoshaug - 21/6/2007 6:47 AM
As an example, the STS-117 approaches for orbits 202 and 203 are from the south, but the final approaches shown in the ground tracks on NASA's website show touchdown from the north (Runway 15 end of SLF). Attached is orbit 202 / Runway 15 (which can be redesignated to 33, of course)...
Thanks. Especially that bit about noctilucent clouds and ice crystals was interesting.
whitewatcher,
It is true that they rely on landing aids, but this is installed on both ends of the runway (often they make the final decision on which runway to use during the reentry based on wind directions). Once the orbiter is directly above the runway, it doesn't really matter if you turn about 270° left or about 270° right to align with the runway of choice, no matter if the reentry sees the shuttle approaching from northwest or southwest.
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#438 by mkirk on 21 Jun, 2007 12:22
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gispa - 21/6/2007 3:20 AM
I have a question about reentry procedure: in the normal operations the pilots in the space shuttle performes te reentry automaticly? and which is the point where they take the manual control of the spacecraft? thank you.
Typically the commander will take CSS (control stick steering - i.e. manual control) for Roll, Pitch, and Yaw after the orbiter goes subsonic at MACH .9 - this usually occurs at about 4 minutes to go before tocuhdown.
Mark Kirkman -
#439 by rfoshaug on 21 Jun, 2007 13:05
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Also, the pilot usually (always?) flies part of the HAC to get some experience piloting the shuttle. The commander then takes control again for landing.
