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#840 by sbt on 28 Nov, 2009 17:44
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I haven't seen the video, but I heard that the poor tech screamed all the way down.
As I understand, this system is designed to get the crew out of harm's way of an imminent explosion, hence made for speed not necessarily safety. It would never be considered for use during a normal abort.
Agree. Think of it this way - (discounting the damage to the aircraft) would you use an Ejector Seat for normal exit from an aircraft? Or a free-fall lifeboat rather than the ships tender?
Many escape systems are inherently dangerous - it's just that they are less dangerous than what you are escaping FROM.
Rick -
#841 by Lee Jay on 28 Nov, 2009 18:02
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I haven't seen the video, but I heard that the poor tech screamed all the way down.
As I understand, this system is designed to get the crew out of harm's way of an imminent explosion, hence made for speed not necessarily safety. It would never be considered for use during a normal abort.
I think the "poor tech" was none other than Charlie Bolden:
http://en.wikipedia.org/wiki/Charles_F._Bolden,_Jr.
"Bolden was the first person to ride the Launch Complex 39 slidewire baskets which enable rapid escape from a space shuttle on the launch pad. The need for a human test was determined following a launch abort on STS-41-D where controllers were afraid to order the crew to use the untested escape system." -
#842 by Danderman on 29 Nov, 2009 14:32
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http://spaceflight.nasa.gov/gallery/images/station/crew-21/hires/iss021e032920.jpg
What are the two objects that remain the STS-129 payload bay in this flyaround image? Are these remnants of the two ELCs that were transported to ISS by STS-129? -
#843 by The-Hammer on 29 Nov, 2009 15:08
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Yes.
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#844 by orbiter62995 on 29 Nov, 2009 18:04
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Which females in the astronaut corps can spacewalk that are active at this time? What males cannot?
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#845 by Jim on 30 Nov, 2009 16:24
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Which females in the astronaut corps can spacewalk that are active at this time? What males cannot?
all can and all males -
#846 by ponybottle on 04 Dec, 2009 20:45
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Hi All !
Well this is my first post to the site and if it doesn't make much sense then blame the half bottle of merlot coursing through my veins which I unwisely (?) consumed before comming to the keyboard.
Now this is probably the dumbest question ever posted to this site ( well I am Oirish and we don't get many astronoughts in this neck of the woods )
Orrrrrrrrr - this is the cleverest post ever written in which they may be moving the Cape to Dublin in the near future to take advantage of the expertise in this here Emerald Isle
My query is - if the shuttle main engines burn 1000 gallons per second and if it takes 7 seconds to clear the tower why do they not just build a bit of a hill first ( I mean I know Floridians don't know what a hill is but it is basically a pimple on the landscape ) I mean you build a hill thing about as high as the gantry and THEN stick the shuttle on top. Hey Presto ! ( or is it Begorah? - can't remember - we are all just getting toooo cosmopolitian in this global village these days ) you save 7000 gallons of fuel which translates ( very roughly ) to 30 tons of payload !
Now either I am totally wrong ( blame the Merlot ! ) or by building some wee hills you get an awful lot more into orbit with stone age technology.
Go on - tell me I'm wrong ( you'll probably be right ! )
Cheers y'all
Chris -
#847 by Antares on 04 Dec, 2009 22:06
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Because it has to go from 0 to 100 mph no matter what. The kinetic energy of LEO is an order of magnitude greater than the potential energy.
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#848 by rdale on 05 Dec, 2009 00:30
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How would you get the shuttle up there?
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#849 by ponybottle on 05 Dec, 2009 01:20
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Because it has to go from 0 to 100 mph no matter what. The kinetic energy of LEO is an order of magnitude greater than the potential energy.
I think a longer explantion is required for this no doubt learned reply to be meaningful to this writer.
I think the point being made is that the vehicle is already moving at 100mph by the time it reaches the top of the tower and so if you shut down the engines at that point the momentum would carry it a good deal further so my simplistic assumption that the first 30 ton of fuel only gets it to the top of the tower and no further is obviously wrong.
Still begs the question how much fuel does the shuttle have to burn to just get it to the top of the gantry ? i.e the amount of extra payload it could carry if the pad itself were at this height ?
Cheers
Chris -
#850 by Lee Jay on 05 Dec, 2009 01:28
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Still begs the question how much fuel does the shuttle have to burn to just get it to the top of the gantry ? i.e the amount of extra payload it could carry if the pad itself were at this height ?
Let's say, by magic, I placed the orbiter and the stack, at the height of its final orbit (not just a measly few hundred feet above the ground). You know how much fuel that would save? Around 10%.
The point is, most of the energy needed to get to orbit is *speed* not *height*.
EDIT: According to the CEPE spreadsheet, the payload advantage of 100 meters of launch pad altitude is 4 kg.
EDIT 2: If that's not enough brain twisting for you, let's say you use a giant slingshot to save those 30 tons of fuel by flinging the whole stack to 100mph. You know how much extra cargo that would get you? About 1.5 tons, assuming I didn't horribly mess up that calculation. -
#851 by Orbiter on 06 Dec, 2009 13:05
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What was the first mission to use an OMS burn during the ride uphill?
Similarly, what was the first mission to roll to a heads-up position during launch?
Orbiter
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#852 by psloss on 06 Dec, 2009 13:13
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What was the first mission to use an OMS burn during the ride uphill?
Already asked in this thread...question post is here:
Similarly, what was the first mission to roll to a heads-up position during launch?
http://forum.nasaspaceflight.com/index.php?topic=17437.msg419994#msg419994
Answers follow.
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#853 by Mike_1179 on 09 Dec, 2009 14:27
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My query is - if the shuttle main engines burn 1000 gallons per second and if it takes 7 seconds to clear the tower why do they not just build a bit of a hill first
Wayne Hale had a pretty decent write-up of the energy needed (both potential and kinetic) needed for various things. It's all about velocity.
http://blogs.nasa.gov/cm/blog/waynehalesblog/posts/post_1251819060090.html
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#854 by tminus9 on 10 Dec, 2009 15:52
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I'm trying to get a better understanding of how attitude is specified for the orbiter. I've read through many of the docs available on L2 and resources on the web, but still have a few questions.
I believe that for LVLH attitude, Euler angles are specified in a pitch-yaw-roll (2-3-1) sequence, but I don't know whether the convention is to give the angle to rotate the body frame to the LVLH frame or vice-versa. Is there a standard convention for this?
Obviously, it makes a difference in the sign of the angles, but does it also make a difference in the sequence? In other words, if the PYR angles are (40, -10, 60) to rotate the LVLH frame to the body frame, is it correct that the Euler angles to rotate from the body frame to the LVLH frame are (1) also pitch-yaw-roll sequence and (2) the same values with opposite signs, that is (-40, 10, -60)?
Do the same answers apply to the inertial (M50) attitude, which I think is also pitch-yaw-roll sequence, and the LVIY attitude used during ascent?
During STS-129, I monitored the Java applet-based NASA orbital tracker (http://spaceflight.nasa.gov/realdata/tracking/index.html) and noticed that the attitude is frequently displayed there. Does anyone know relative to which frame this attitude is given? I noted some examples over the course of the mission, and I can dig those up. The applet also shows ISS attitude, which I would guess is relative to LVLH.
Again, please correct me if I'm wrong on any of this. I've seen contradictory information at times. Thanks for the information. -
#855 by DaveS on 10 Dec, 2009 18:53
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Anyone know how many degrees around the SRB Y axis that the FWD BSMs are clocked?
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#856 by Jorge on 11 Dec, 2009 00:55
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I'm trying to get a better understanding of how attitude is specified for the orbiter. I've read through many of the docs available on L2 and resources on the web, but still have a few questions.
I believe that for LVLH attitude, Euler angles are specified in a pitch-yaw-roll (2-3-1) sequence, but I don't know whether the convention is to give the angle to rotate the body frame to the LVLH frame or vice-versa. Is there a standard convention for this?
Obviously, it makes a difference in the sign of the angles, but does it also make a difference in the sequence? In other words, if the PYR angles are (40, -10, 60) to rotate the LVLH frame to the body frame, is it correct that the Euler angles to rotate from the body frame to the LVLH frame are (1) also pitch-yaw-roll sequence and (2) the same values with opposite signs, that is (-40, 10, -60)?
Do the same answers apply to the inertial (M50) attitude, which I think is also pitch-yaw-roll sequence, and the LVIY attitude used during ascent?
The Euler sequence is for reference-to-body rotation, whatever the reference (M50, LVLH, LVIY, etc). Start with the body frame aligned with LVLH, then apply the rotations to the body in pitch-yaw-roll sequence to arrive at the proper attitude.
To go the opposite direction, you need not only to reverse the sign of the angles, but also to reverse the sequence (roll-yaw-pitch). It is possible, of course, to compute a pitch-yaw-roll sequence for the reverse rotation, but the angles won't just be sign-reversed, they'd be different angles. -
#857 by Lee Jay on 19 Dec, 2009 02:51
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When the orbiter is powered down and on an extended stay in the un-air-conditioned VAB, do they feed some of the systems purge air/gasses?
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#858 by Jim on 19 Dec, 2009 11:55
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There are conditioned air purges through the T-0, just like the pad.
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#859 by psloss on 27 Dec, 2009 18:21
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Space shuttle Challenger STS 7 was suppose to be the first landing at KSC, but i have heard that it was delay from low clouds at the area and landed at Edwards instead. why didn't they land Challenger at KSC the next day.
The flight control team declared one of the APUs (#3) suspect due to an underspeed during its initial run for the flight control system checkout the day before landing. Would also note that this was early in the program and I wouldn't assume the flight rules were the same as today.
