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#260
by
Chris Bergin
on 13 Jan, 2006 12:38
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Jonesy STS - 13/1/2006 1:22 PM
There never seems to be a lot of people near the countdown clock. Why is this?
It's a VIP/Press Area. The bulk of people watching are outside KSC property.
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#261
by
possum
on 13 Jan, 2006 13:27
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Also, they don't let people at the Press Site wander around wherever they want to go. I believe that the area in front of the countdown clock is off-limits. After all, there are potentially hundreds of millions of people watching on TV and you wouldn't want a crowd of people in front of the countdown clock. The countdown clock is situated down front where it can be seen with the Pad in the background, and that is exactly where everyone would want to stand to get the best view of launch.
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#262
by
mkirk
on 13 Jan, 2006 16:24
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Very Good Summary!
My only point in my original message (not worded very well) about the fire commands was that in the command itself as I recall the hold down seperation is before ignition within the same command stream. When I first went thru my training the instructor made a big point of saying that "we send the command to seperate the hold down posts before we send the command to ignite the SRB"...at the time I was surprised and confused especially because section 1 of the shuttle flight manual (which is never the final word on the specifics of shuttle operations) at the time indicated that the hold down release command was a function of thrust-to-weight after SRB ignition. To resolve the confusion I as the student was tasked to find the correct answer. Which is what you have summarized from the STS NEWS REF and because of the way the arm/fire commands are ordered within the command string itself, hold down fire is before ignition.
In regard to cutoffs or on-pad aborts: no cutoff capability exists once the T-0 command is issued regardless of what happend to the SSMEs, SRBs, T-0 umbilicals, or hold down bolts in the interim.
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#263
by
possum
on 13 Jan, 2006 17:27
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The link to the STS-68 video does not work for me. The dialog box says cannot connect to server. Has anyone else had any problems with this link?
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#264
by
possum
on 13 Jan, 2006 17:56
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Just to change the subject a little. For those who may wonder why the Shuttle turned out to be so much more expensive than planned, one of the reasons is the operational complexity driven by requirements creep and an enourmous amount of servicing required to turn the Orbiter around from one flight to the next. Nothing demonstrates this better than the early concept for processing of the Orbiter versus the actual system, depicted in the following two images:
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#265
by
Mark Max Q
on 13 Jan, 2006 19:39
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Did they honestly believe they'd have an OPF looking remotely like the first image? Of course, we know what an OPF looks like now, but I can't but help to think that an artist got the wrong memo somewhere!
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#266
by
Mark Max Q
on 13 Jan, 2006 19:41
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rmathews3 - 13/1/2006 12:27 PM
The link to the STS-68 video does not work for me. The dialog box says cannot connect to server. Has anyone else had any problems with this link?
It's not working for me either. They don't appear to have a very good server for the videos, or it's all one server. This site has a seperate high speed FTP server for the video downloads, which is why it's fast and can handle demand. The other site might be back up later, so it's worth trying again.
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#267
by
braddock
on 13 Jan, 2006 23:29
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Mark Max Q - 13/1/2006 3:39 PM
Did they honestly believe they'd have an OPF looking remotely like the first image? Of course, we know what an OPF looks like now, but I can't but help to think that an artist got the wrong memo somewhere!
I found an interesting 1995 report at
http://science.ksc.nasa.gov/shuttle/nexgen/rlvhq10.htm that used the same two OPF pictures:
The economic plan used to develop the operations scenario for the shuttle was a five orbiter fleet with a projected flight rate of forty flights per year from the John F. Kennedy Space Center (KSC) and an additional twenty flights per year from Vandenberg Air Force Base (VAFB). Early analyses confirmed that forty flights from KSC could only be achieved if vehicle ground turnaround could be completed within 160 hours, hence the 160 hour turnaround allocation. The 160 hour allocation processing timeline included initial operations and safing, orbiter test operations, post flight trouble-shooting, Space Shuttle Main Engine/Main Propulsion System (SSME/MPS) operations, cargo operations, Thermal Protection System (TPS) maintenance & repair, maintenance & servicing, element integration, fluid servicing and countdown. Allocations were also developed for facility maintenance and turnaround. These timelines were accepted and used as program requirements/goals and assessments of the allocated timelines were performed.
The STS was AMBITIOUS! 60 flights per year...roll the shuttle into the hanger on Monday, kick the tires, lift it onto a new stack by Friday...what a world that would have been...
The report section concluded:
However, because 1) non-recurring cost, 2) Design, Development, Test, and Evaluation (DDT&E) schedule, and 3) weight penalties were a higher priority than long-term operational benefits, most recommendations for a more supportive design were not adopted. Therefore, supporting the design was not compatible with allocated timelines or reaching the mission cost goal of $15 million/flight.
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#268
by
anik
on 14 Jan, 2006 11:44
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anik - 3/1/2006 12:40 AM
Does anybody has exact times of Shuttle launches (within milliseconds)?…
I collect the time of "SRB ignition command from GPC", which is considered as official time of Shuttle liftoff... For example, the official time of Challenger (51-L) launch was "16:38:00.010 UTC – SRM Ignition Command (T=0) – 0.000 – GPC"…
P.S.: Good source, but there are not all times... 
http://spaceflight.nasa.gov/shuttle/reference/green/lanlanto.pdf
I do not want to be importunate or annoying...
But could anybody help me with exact times of Shuttle launches?... Does anybody has the old reports or documents, which contain these exact times?...
PP.S.: Another good source, but there are not all times also...
http://members.aol.com/WSNTWOYOU/mainmr.htm
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#269
by
FransonUK
on 14 Jan, 2006 12:49
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Have you tried a search. I'm sure Chris wrote them down from the Challenger Accident investigation, where they used milliseconds.
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#270
by
James Lowe1
on 14 Jan, 2006 13:38
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It might have to wait while his back, remember he's with British Army most of the weekend daytime.
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#271
by
Chris Bergin
on 15 Jan, 2006 19:00
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Let me find the DVD and I'll list them. They do work to the millisecond on the report.
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#272
by
mkirk
on 17 Jan, 2006 02:24
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I submited this as a reply to the STS-3 video thread but thought the Shuttle Q&A folks might be interested in this. In my hurry to type the original I made a couple of typos and since I couldn't get EDIT to work I just fixed it with a new post.
FYI – in Response to the STS-3 video thread, just a few words about landing shuttles.
In Jack Lousma’s defense, there is not a single shuttle commander, pilot, or training instructor who doesn’t realize just how easy it would be to over rotate the orbiter’s nose like the STS-3 landing…“But for the grace of God go I” has probably entered every commanders mind…Shuttle landings are very public, even with minimal news coverage, and I am sure every commander has an internal dialogue running that goes something like “don’t let me #@!? this up”. It is not uncommon after a simulation that didn’t quite go as the student had hoped to here either the student or instructor say…”you know that wasn’t pretty, but if this were real it would certainly give them something to talk about on CNN”:). Every aspect of the commander’s performance is analyzed by engineers, pilots, and even the public. Data after landing shows how often you moved the stick, how much force you used…you can tell if you were on speed, on altitude on the HAC, did you land too hard, too long or short, did you land to far to the left or right, did you touchdown with the left or right gear first. I observed a landing not to long ago where as the orbiter rolled to a stop the news commentator made a big point out of the fact that the nose wheel was not on the centerline of the runway…for a self respecting pilot that’s are large number of eyeball’s second guessing your work.
As for how shuttles are landed today…The parameters have been modified over time and as experience was gained; but this is the current technique.
On final as the orbiter descends thru 2000 feet the Pre-Flare begins and the commander sitting in the left seat and flying the orbiter manually, calls “Arm the gear”. At that point the pilot sitting in the right seat will push a button on the forward instrument panel just in front of his control stick. Meanwhile the commander, who has been flying a steep outer glide slope of 18 or 20 degrees (depending on orbiter weight), and an airspeed of about 300 knots, will begin a 1.3g pitch up by pulling back on the stick. This is done to position the orbiter on the much shallower 1.5 degree inner glide slope. During the approach the pilot is calling out altitude and the mission specialist number 2 (MS2 the flight engineer on all missions) will call out speed brake settings. As the orbiter descends thru 300 feet (+/- 100 feet) the commander will call “Gear Down” and the pilot will push the deploy push button on the forward instrument panel. The gear will come down immediately…this actually occurs less than 20 seconds before touch down (down and locked by about 10 seconds). The commander will then begin the final flare of the orbiter by pulling ever so gently on the stick. The goal is to cross the runway threshold at about a height of 20-30 feet. During this time the pilot is calling both altitude and airspeed in a steady cadence like this “50 feet at 250…40 at 240… 30 at 230…” The commander is nominally aiming to touchdown at a point 2500 feet down the runway at a sink rate of less than 3 feet per second and airspeed of 195 or 205 knots (speed is dependent on orbiter weight). The touchdown zone is marked by long white stripes on the runway…so if you land early or late the outside world has the ability to instantly critique you. At touchdown the MS2 will verify that the speed brake is moving to the full open position as the commander holds the nose up to take advantage of aerodynamic breaking. As the orbiter slows below 195 knots the commander will call “chute”, and the pilot will push the “ARM” and “Fire” buttons on the glare shield next to the heads up display. This deploys the drag chute with a noticeable jolt in the cockpit as it unreafs (you can see this jolt on the in-cockpit videos). The chute helps relieve brake workload, aids directional control, and relieves gear loads. At 185 knots the commander begins to de-rotate (i.e. lower the nose to the ground) at a rate of about 1-2 degrees per second. This in nominally done by pressing forward on the “Beep” trim switch located on the control stick, not by using the stick itself. The trim provides a more precise 1.5 degree per second pitch down rate and helps prevent the commander from slamming the nose down to hard (such as STS-3). The MS2 at this time will cycle the SRB SEP switch and push the SRB SEP push button on the center console…YES HE REALLY DOES THIS…this action sets a software discrete in the guidance system that tells the computers to use different control logic now that the orbiter is on the ground. This is known as setting the “WONG” or weight-on-nose-gear indication. The pilot continues to call out speed as well as distance to the end of the runway in thousand foot increments as the commander applies the brakes by pushing on the top portion of the rudder pedals and tries to maintain the nose on the center line (so CNN won’t complain). At 60 knots the commander calls “Chute” and the pilot pushes another button to jettison the drag chute. This is done while the orbiter is still moving to make sure the chute does not land on the engine bells as the orbiter rolls to a stop. The final call from the commander is made to Houston…”Houston, Discovery…wheels stop”. At that time seemingly as if it were written in the checklist the CapCom in Houston will congratulate the crew with a “welcome home”, “job well done”, “you have single handedly saved the world yet again:)…”
I hope you don’t mind the excessive detail folks!
Mark
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#273
by
Sergi Manstov
on 17 Jan, 2006 10:40
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Mkirk, that is a very interesting read. Is a lot of the hardness in landing because they are so heavy? Buran could land unmanned, but was lighter with no main engines because Energia boosters were very good
Was the heavyness of the US orbiter a big problem for landing?
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#274
by
possum
on 17 Jan, 2006 14:53
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Launch Fan - 12/1/2006 12:44 PM
A question, if I may, which will sound stupid, so I appologize in advance.
I have read that a team stays at the pad during launch, in case of a pad abort where the astronauts have to escape. Is this right? I know the Red Team do the final checkout of the systems, but I didn't think anyone would be able to stay near the pad, in the RSS I read, during the launch?
Nobody is on the pad during launch, it would be lethal. The noise alone would be enough to turn your brain to mush. The Fire/Rescue folks are staged at an area closer than anyone else is allowed, but I'm not sure where that is these days. I have seen pictures of them staged about 1/2 mile up the Crawlerway (pre-Challenger), but I doubt if they are that close these days. Maybe someone else knows exactly where they are staged, but it is most definitely not at the pad itself, not even the adjacent pad (8,000 feet away).
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#275
by
Launch Fan
on 17 Jan, 2006 16:03
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Thanks, that makes sence, but I wasn't sure.
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#276
by
psloss
on 19 Jan, 2006 00:33
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OK, I have a question for Mark (mkirk) regarding contingency aborts; I've been curious about the ECAL abort for a long time, but I realize that the questions are essentially hypotheticals.
To start with, I'm curious if there are any "pre-TAL" two or three engine out scenarios where the orbiter could still make an intact landing or would those always result in a bailout and loss of vehicle? For example, could the orbiter make Myrtle Beach on a high-inclination launch in that kind of situation? An RTLS-style ET separation sounds nasty enough, but is it difficult to put ET in the water and still get back to an airfield?
(Sorry, that's way more than one question; like I said, I'm curious about this.)
Philip Sloss
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#277
by
mkirk
on 19 Jan, 2006 00:33
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Hi Sergi-
No, I wouldn't say that the orbiters weight in itself makes shuttle landings any more dificult. I only mentioned wieght in my previous discription because the glide slope (18 or 20 degrees) and the touchdown speed (195 or 205 knots) is based on orbiter weight. heavey orbiters use 18 degrees and 205 knots while lightweight orbiters will use 20 degrees and 195 knots. This just optimizes the energy of the orbiter so that the touchdown point can be achieved at a speed that will not exceed the structural limits of the landing gear. Weight is of course a function payload and an orbiter that weighs more than 220,000 pounds at landing time is considered heavy.
Weight is not really the problem for entry and landing, energy management is. What did add to the complexity of landing shuttles was the early design requirement for a relatively large crossrange capability. I believe this was a Department of Defense requirement. This is why the orbiter ended up with the delta wing shape which inturn defined the entry and landing flight envelope. During early entry the orbiter flys with an angle of attack (alpha) of 40 degrees to disipate energy by increasing drag, however,the orbiter has only a 3 degree alpha envelope. If this 3 degree envelope is exceeded you will either burn the orbiter up, over stress the orbiter (too many G's), or depart controlled flight...all of these are bad!!! Since the pilot/flight control system can not use pitch to manage drag, descent rate, and airspeed the only alternative is to change the bank angle of the orbiter which changes lift and in turn manages the amount of drag. If you have seen animation of early entry these roll maneuvers look more like yaw maneuver than a roll because the nose is pitched up so high.
As for the last phase of the shuttle landing (from 50,000 feet lets say), the techniques for this style of energy management were actually developed during the late 50's and early 60's out at Edwards. Aircraft such as the F-100, F-104, X-15, and the lifting bodies were used to develope high energy high speed landing procedures. They all used a low lift to drag approach that looks a lot like a dive bomb run in a modern fighter jet because of the steep high speed approach.
Mark
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#278
by
Avron
on 19 Jan, 2006 05:07
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I saw something on a launch video a few days ago that I did not expect to see, and that is an umbilical attached to the tank behind the left SRB, it appeared to drop away after T-0. Now I know that the umbilical lines go in the aft of the orbiter, via the two service masts around the aft end of the orbiter...
Question, what is this tank umbilical for?
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#279
by
DaveS
on 19 Jan, 2006 07:34
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Avron - 19/1/2006 7:07 AM
I saw something on a launch video a few days ago that I did not expect to see, and that is an umbilical attached to the tank behind the left SRB, it appeared to drop away after T-0. Now I know that the umbilical lines go in the aft of the orbiter, via the two service masts around the aft end of the orbiter...
Question, what is this tank umbilical for?
That is the so called Ground Umbilical Carrier Assembly or GUCA for short. It vents the LH2 from the LH2 tank in the ET. It's similar to th Gaseous Oxygen Vent Arm which is covering the top of the ET. You don't want any free H2 since it is a big explosion risk.
I remember when NASA scrubbed an STS-110 launch attempt to huge leak of LH2 was seeing emerging from a pipe on the Mobile Launch Platform.
