Post by: Terry Rocket on 10/15/2005 11:05 am
Shuttle Q&A Part 1 (http://forum.nasaspaceflight.com/index.php?topic=625)
Shuttle Q&A Part 2 (http://forum.nasaspaceflight.com/index.php?topic=2030)
Shuttle Q&A Part 3 (http://forum.nasaspaceflight.com/index.php?topic=6156)
Shuttle Q&A Part 4 (http://forum.nasaspaceflight.com/index.php?topic=10600.0)
Shuttle Q&A Part 5 (http://forum.nasaspaceflight.com/index.php?topic=17437.0)
Post by: FransonUK on 10/15/2005 11:12 am
Post by: Terry Rocket on 10/15/2005 12:15 pm
Ok, this is basic, so please try to answer with basic answers otherwise I'll get stuck! ;)
Q) Launches are very powerful and I've seen clips of the Astronauts been shaken around etc. Yet they have a pilot on board, so how does he/she fly the Shuttle whilst been shaken about, such as the roll which looks like it has to be just right?
Post by: Chris Bergin on 10/15/2005 01:13 pm
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Terry Rocket - 15/10/2005 1:15 PM
Thanks!
Ok, this is basic, so please try to answer with basic answers otherwise I'll get stuck! ;)
Q) Launches are very powerful and I've seen clips of the Astronauts been shaken around etc. Yet they have a pilot on board, so how does he/she fly the Shuttle whilst been shaken about, such as the roll which looks like it has to be just right?
Welcome to the site, Terry.
A) The pilot doesn't fly the Orbiter (the part of the Shuttle that added to the Solid Rocket Boosters and External Tank makes up the Shuttle) like a normal plane. The Orbiters are driven by flight computers and the astronauts pretty much just sit back and make any required corrections on assent, but it really is all down to the Orbiter. The main two astronauts on the Orbiter's flight deck are the Commander and the Pilot in the front two seats. They are used more on landing (after coming back through re-entry - which again the Orbiter flys herself through).
Post by: Terry Rocket on 10/15/2005 01:26 pm
Another one:
Q) Why are there sparks just before the main engines fire up? Is that what ignites the fuel? Just seems a bit dangerous!
Post by: WARPed on 10/15/2005 01:42 pm
Post by: Flightstar on 10/15/2005 01:53 pm
Quote
Terry Rocket - 15/10/2005 8:26 AM
Q) Why are there sparks just before the main engines fire up? Is that what ignites the fuel? Just seems a bit dangerous!
Warped pretty much answered that exactly.
Here is a picture of the event that happens just shortly after T-10 seconds.
Post by: Terry Rocket on 10/15/2005 01:57 pm
Post by: Flightstar on 10/15/2005 06:41 pm
Post by: Tahii on 10/15/2005 10:39 pm
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Terry Rocket - 16/10/2005 12:15 AMWelcome to the site. I am kind of in the same boat. Its good to see people who don't know something wanting to find an answer.
Ok, this is basic, so please try to answer with basic answers otherwise I'll get stuck! ;)
Post by: discovery_fan on 10/16/2005 04:48 pm
Afaik the orbiter is after Main Engine Cut Off not yet in an orbit, and has not the right speed to go into orbit (thats why the ET descends into the indian ocean, I think). To get to the orbit the Orbital Maneuvering Engines are fired, twice I think usually, first to get into an elliptic orbit and then into the final planned orbit (each time adding some couple of hundred kilometers/hour of speed).
Right?
When the Orbiter needs to go to a higher then usual orbit (maybe to deploy a spaceprobe or to catch the Hubble ST), does it simply fire the OMEs longer (additionally to having a lighter payload)? Or do the SSMEs burn longer as well and the orbiter with ET goes higher up?
Or another way to ask the question:
Is MECO (and ET seperation) allways at the same altitude or does it vary? If it does vary is there a possibility that the MECO is so late that the ET goes into a low orbit itself and circles the earth a couple of times or can that never happen?
Post by: Rocket Guy on 10/16/2005 05:36 pm
The Orbiter fires its OMS to circularize the orbit.
Post by: Orbiter Obvious on 10/16/2005 08:24 pm
Post by: Chris Bergin on 10/16/2005 08:32 pm
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Orbiter Obvious - 16/10/2005 9:24 PM
Would it be ok to ask for some of the likes of MECO to be explained in the words those letters stand for?
Sometimes you'll see it mentioned, such as MECO, just got to look out for it and associate. However, here's a few reeled off (one's you might see a lot of around these parts) as reference.
STS = Space Transportation System
ET = External Tank
OV = Orbiter Vehicle (such as OV-103 is Discovery, 04 is Atlantis, O5 is Endeavour)
SRB = Solid Rocket Booster
OMS = Orbital Maneuvering System
RCS = Reaction Control System
MPL = Mobile Launch Platform (Rides on the Crawler Transporter, Shuttle Stack goes on top of the MLP).
VAB = Vehicle Assembly Building
MECO = Main Engine Cut Off
SSME = Space Shuttle Main Engine
MAF = Michoud Assembly Facility
MSFC = Marshall Space Flight Center
KSC = Kennedy Space Center
RLV = Reusable Launch Vehicle
LOX = Liquid Oxygen
LH2 = Liquid Hyrogen
ECO = Engine Cut Out (sensor)
If anymore pop into my head, or the question is asked, I'll edit and add here.
Post by: MKremer on 10/16/2005 08:40 pm
and its counterpart:
ELV = Expendable Launch Vehicle
Post by: Orbiter Obvious on 10/16/2005 08:42 pm
This site is great, but if I was to go to say three sites a day to get as much Shuttle news as possible, which other two would I go to?
Post by: Chris Bergin on 10/16/2005 08:48 pm
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Orbiter Obvious - 16/10/2005 9:42 PM
Very cool thanks.
This site is great, but if I was to go to say three sites a day to get as much Shuttle news as possible, which other two would I go to?
For me, spaceref.com and spaceflightnow.com
We're getting to the stage where the forum (in my humble opinion) is going to be the best space flight forum around (expondentially getting busier and doesn't insist on the bulk of its posts being non-related to the site).
The news section of the site does its job but won't be where I want it till we've got 20 writers in the pool. We're aiming for that as we have a few good writers already active, but you'll see just next week how we're going to do this. There's a Langley story being finalised as we speak where the writer is actually involved in the program. This is the kind of reporting we are looking to have here....but it'll take time and won't be "in replacement of" the aforementioned sites. We want people to go to all space related sites. Our aim is that we're one of those sites you go to.
Post by: MKremer on 10/16/2005 08:58 pm
Agreed.
Spaceref.com stays pretty up-to-date on the latest NASA and space-related press releases and updates (in the right hand column).
And, during special events (launches, dockings, spacewalks, landings), Spaceflightnow.com's event Mission Status Centers are about the next best thing to watching a live feed.
Post by: Flightstar on 10/17/2005 12:23 am
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Ben - 16/10/2005 12:36 PM
It's not the speed, it's the fact that after the SSMEs cut off, the orbit is too elliptical. The ET reenters quickly because this elliptical orbit plunges it back into the atmosphere on the other side of earth. The Shuttle would take the same route if it did not fire its OMS engines. In fact, that is what it would do if it were to do an "abort once around" emergency landing.
The Orbiter fires its OMS to circularize the orbit.
Very well put.
Post by: Do Shuttles Dream on 10/17/2005 03:22 am
Quote
Chris Bergin - 16/10/2005 3:32 PMQuoteOrbiter Obvious - 16/10/2005 9:24 PM
Would it be ok to ask for some of the likes of MECO to be explained in the words those letters stand for?
Sometimes you'll see it mentioned, such as MECO, just got to look out for it and associate. However, here's a few reeled off (one's you might see a lot of around these parts) as reference.
STS = Space Transportation System
ET = External Tank
OV = Orbiter Vehicle (such as OV-103 is Discovery, 04 is Atlantis, O5 is Endeavour)
SRB = Solid Rocket Booster
OMS = Orbital Maneuvering System
RCS = Reaction Control System
MPL = Mobile Launch Platform (Rides on the Crawler Transporter, Shuttle Stack goes on top of the MLP).
VAB = Vehicle Assembly Building
MECO = Main Engine Cut Off
SSME = Space Shuttle Main Engine
MAF = Michoud Assembly Facility
MSFC = Marshall Space Flight Center
KSC = Kennedy Space Center
RLV = Reusable Launch Vehicle
LOX = Liquid Oxygen
LH2 = Liquid Hyrogen
ECO = Engine Cut Out (sensor)
If anymore pop into my head, or the question is asked, I'll edit and add here.
Thanks. Most message boards laugh you off the forum for not knowing all that.
Post by: realtime on 10/17/2005 03:49 am
What would it take for a shuttle derived launch vehicle (SDLV) ET?
Post by: Flightstar on 10/17/2005 03:56 am
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realtime - 16/10/2005 10:49 PM
Some people have kicked around ideas of repurposing external tanks (ETs) for orbital hotels. Just to play some games here, what would it take to circularize a shuttle ET's orbit?
What would it take for a shuttle derived launch vehicle (SDLV) ET?
I believe that works on the notion of a similar possibility as Skylab, a stage of a Saturn V, which I wouldn't wish to entertain with an ET of a SDLV, given the internals of ETs. You'd have to change the struction and materials, as I don't believe it would survive all that long, not to mention the amount of unviable work needed one you got it up there, plus the viability of getting it in orbit etc. too many headaches.
Post by: realtime on 10/17/2005 04:38 am
Quote
Flightstar - 16/10/2005 11:56 PMFrom a layman's POV it's just so tempting. All that empty space, that high up. Doggone thing is almost in orbit... ;)Quoterealtime - 16/10/2005 10:49 PM
Some people have kicked around ideas of repurposing external tanks (ETs) for orbital hotels. Just to play some games here, what would it take to circularize a shuttle ET's orbit?
What would it take for a shuttle derived launch vehicle (SDLV) ET?
I believe that works on the notion of a similar possibility as Skylab, a stage of a Saturn V, which I wouldn't wish to entertain with an ET of a SDLV, given the internals of ETs. You'd have to change the struction and materials, as I don't believe it would survive all that long, not to mention the amount of unviable work needed one you got it up there, plus the viability of getting it in orbit etc. too many headaches.
And it seems like such a waste to throw that monster away. Think of all the things we could do with such a beast.
http://www.permanent.com/p-extank.htm
Or maybe they could be turned into fuel depots?
http://www.aiaa.org/tc/sos/communicator/jan_mar_2004/supply_depots.html
OK. I realize that I'm heavy into Blue Sky territory here, but these things are on the hairy edge of feasibility. They're worth re-examining as the technology changes. Sooner or later, it may make sense to do it.
So, what would it take to circularize an ET orbit? Could it be done with SDLV main engines?
Post by: simcosmos on 10/17/2005 10:49 am
It would be *very easy* to place the ET into a circular orbit, even with today's STS configuration: there is some fuel percentage left on the ET and all what would be needed would be to just let the SSME engines burn longer and also to adopt a slightly different ascent profile.
The main problems come after that and, among other things, are:
- stabilization of ET (current STS) or new ET (heavy lifter) after shuttle separation / orbital insertion, etc (this means that the ET would need to have some RCS / momentum wheels... if we want to avoid having something BIG floating and spining around with no control!)
- cleaning of ET's interior (assuming that the fuel tanks would be used for living, the remaining fuel would have to be drained… Not as simple as I will write but this could be done with a special hardware that would "suck" almost all remaining fuel - to some kind of smaller tanks - before engines shutdown)
- access to ET's interior: there would have to be some sort of external hatch and connections (tube) allowing astronauts to move between the empty tanks... As a side reference, and if memory does not fail me, it is currently possible to access the intertank area.
- exterior modifications (in order to allow stuff to be attached to the ET, handy if we want to link several ET, add extra modules, add solar panels, etc)
- and the list continues...
Interesting links about the issue (where info can be found about the problems, solutions and also with nice pictures):
http://space-frontier.org/Projects/ET/
http://www.space-frontier.org/Projects/ET/external_tank_application_images.htm
http://www.spaceislandgroup.com/
http://www.spaceislandgroup.com/geode-stations.html
http://www.spaceislandgroup.com/geode-history.html
These links and links inside links should give an interesting reading for hours and hours ;)
António
Who wants to see a "Live" Shuttle Launch?
If some of you wishes, I could organize a little 10 minutes session showing in detail all the steps of a shuttle launch!
All what would be necessary would be:
a) to combine a day / hour (GMT)
b) to visit my Live Pics page:
http://simcosmos.planetaclix.pt/06_multimedia/00_live/go/SIMCOSMOS_LIVEPics.htm
c) optional: to install ventrilo client: http://www.ventrilo.com
Description:
Every 10 seconds I would transmit to my live pics page an image of Orbiter Space simulator. Live video would be better but, given bandwidth limitations, "almost live pics" are the best option for a great number of viewers (I usually only make live video for 1 or 2 persons… However, the image size / quality is much better by using "live" pictures instead ;))
I would then launch the space shuttle (or the SRB launcher or anything you would like to see) and move the external camera around, same for the internal cockpit camera: this would allow people to see what happens in real life with a very high detail given that there is total freedom regarding view angles / zoom.
At the same time, I would transmit sound (by hosting a ventrilo server) and would explain the main phases of the ascent... Once at orbit, I could open the cargo doors, show an EVA… load another scenario with the shuttle ready to dock to a finished ISS, etc.
The ventrilo server, when online, can be accessed via my site's Multimedia > Audio Chat feature. Direct link here:
http://simcosmos.planetaclix.pt/06_multimedia/00_ventrilo/ventrilo_in.htm
Voice communications could then be used to explain what is going on and for people to make any comment / questions.
Just a suggestion ;)
António
Post by: Avron on 10/17/2005 02:33 pm
Post by: Chris Bergin on 10/17/2005 02:38 pm
This might help with a look inside an ET:
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=412&start=1
Post by: Chris Bergin on 10/17/2005 03:28 pm
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Avron - 17/10/2005 3:33 PM
Someone... please explain to me why the PAL and Ice ramps have to be made of Foam?
To keep the weight down, I'm presume...plus it's easier to add foam to foam, rather than anything else. I'm saying that given there was a mention of a mesh chicken wire being added into or over the PAL Ramp as one solution to foam liberation...I don't ever remember any other options bar taking the ramp off.
Post by: simcosmos on 10/17/2005 05:36 pm
Quote
Chris Bergin - 17/10/2005 3:38 PM
Simcosmos:
This might help with a look inside an ET:
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=412&start=1
Hello Chris,
Thanks; I have many sites on the favourites showing how an ET looks likes by the inside/outside, hehehe (photos, videos, tech drawings, concepts…). About videos: by a chance, do have you something showing in detail the maintenance access door(s) located in the intertank area? That would be cool! Hummm, maybe I will (re)try to hunt on the Net for something like that... perhaps NASA has something on the archives...
Related notes and more about how those doors could be used for an ET Station
Also, in the next link(s)...
http://members.tripod.com/~AeroMaster/paper1.htm#Abstract
http://members.tripod.com/~AeroMaster/paper1.htm#C
... it is mentioned, quote:
"(…)After the tanks are purged, an astronaut would open the access hatch on the bottom of the hydrogen tank (opening the access hatch and astronauts passing through it in spacesuits has already been demonstrated in NASA's neutral buoyancy facilities)(…)" >>>>> I would love to see a video of this too!
Back to intertank's access door(s):
http://www.nasa.gov/pdf/2244main_STS112_ET115_FRR.pdf
http://www-pao.ksc.nasa.gov/kscpao/images/large/05pp1774.jpg
http://www.interspacenews.com/sections/photo%20galleries/STS-114%20Photo%20Gallery/DSC_0004rollout.jpg
( http://www.interspacenews.com/sections/photo%20galleries/STS-114%20Photo%20Page.htm )
(see that black square?)
Quote:
"(…)Then just as Discovery was getting ready to roll a hairline crack was found in the foam near the E.T. access door. The E.T. access door provides access to the intertank area during processing and can be seen here as a small black square located in the center of the intertank area.(…)"
And this would be a potencial use (if all others problems were solved, of course):
http://www.orbit6.com/et/price/4_IntertankMods.gif
( http://www.orbit6.com/et/et_price.htm )
Ho, btw, and here it goes one more of those interesting links about ET stuff ;)
http://www.orbit6.com/et/
http://www.orbit6.com/et/gallery.htm
http://www.orbit6.com/et/papers.htm
etc...
António
Post by: Chris Bergin on 10/17/2005 06:28 pm
Quote
simcosmos - 17/10/2005 6:36 PMQuoteChris Bergin - 17/10/2005 3:38 PM
Simcosmos:
This might help with a look inside an ET:
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=412&start=1
Hello Chris,
Thanks; I have many sites on the favourites showing how an ET looks likes by the inside/outside, hehehe (photos, videos, tech drawings, concepts…). About videos: by a chance, do have you something showing in detail the maintenance access door(s) located in the intertank area? That would be cool! Hummm, maybe I will (re)try to hunt on the Net for something like that... perhaps NASA has something on the archives...
Hi Antonio -
Yeah, if you look, and I'll try MAF and MSFC, then we'll see what we can come up with! :)
I know a MAF guy that actually works in that area of the tank as a specialist TPS tech, so I'll see if he can help (he lived in Sidell - which Katrina wrecked, so I know he's currently in Houston - not sure if he'll have access, but I'll try).
Post by: SRBseparama on 10/17/2005 10:32 pm
Post by: James Lowe1 on 10/17/2005 10:35 pm
http://science.howstuffworks.com/space-shuttle10.htm
Post by: simcosmos on 10/17/2005 11:01 pm
Quote
SRBseparama - 17/10/2005 11:32 PM
I can't seem to find it anywhere! Any animations of how a Deorbit burn works?
SRBseparama: shuttle should have 38 holes as RCS (I just loaded the model in the simulator ;) )
(ooops you changed the question, lol)
About the de-orbit and again using the Orbiter space sim: there is a plugin addon (autopilot) that does the procedure just like in real life. By other hand I prefer to do it in manual mode (that would be insane in real life... ho, and I was doing a "hot" reentry... equal to say... going down a little faster and, due to that specific mission nature, with very few S-turns to manage heat build-up and energy... vuuuuch). Anyway, by visiting the next link you and everyone else interested will be able to see a flight report about a fictious space shuttle mission... "From Earth to Earth in two hours"... That report is outdated in some aspects (shuttle addon and simulator versions are not the current ones, for example) and such mission never happened but it is full of nice jpgs showing the space shuttle in action. It has also a few animated gifs (clumsy HAC, on final approach and then for the landing) and... a very short video showing part of the reentry from an external camera and from the cockpit... with the shuttle surrounded by the reentry flames.
In the end it has also some more related links, including a pdf from NASA about how the shuttle lands.
Here goes the link:
STS Simulation - From Earth to Earth in Two Hours - Mission Report
António
PS: Chris: I'm starting to search for videos about the ET access doors but no luck until now
Post by: simcosmos on 10/18/2005 09:03 am
"(…)By other hand I prefer to do it (simulation of shuttle reentry) in manual mode (that would be insane in real life)(…)"
The clarification:
I know that parts of the shuttle reentry were already "hand flown". In fact, what I usually do is very similar to what happened in the first few shuttle missions: the nose of the shuttle and general attitude automatically maintained by the computers with the astronaut having the possibility to "manually override" and change bank, yaw and picth. This became fully automatic. Another "manual part" was the entrance / exit of Terminal Area >> Energy Management part of the flight (around 100Km to runway, 25km altitude, still going fast). However, since many missions that all these procedures are fully automatic (read completely hands off) with the pilot and commander just taking the controls in the very final part, for the approach and landing (more or less 40Km to runway, subsonic)…
"Manual control" can be taken in any other part… if something very bad happens… as it seems that was the case with STS-107 (commander taking "manual control" to compensate for big correction made by RCS due to the wing damage(?) >>> must check this)
Just to conclude: when I wrote "manual control of the shuttle during reentry would be insane" I was more referring to the non-nominal reentry procedure I simulated and not as such as the complete impossibility to really take "manual control" (but always with the aid of the computer, note... there is not such thing as direct manual control)… although… if that ever happens nowadays… it should usually mean something very bad… Hope I had not confused… Had few time to write this :)
cya,
António
Post by: FransonUK on 10/19/2005 08:17 pm
Post by: Flightstar on 10/19/2005 08:27 pm
Post by: Flightstar on 10/19/2005 08:29 pm
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FransonUK - 19/10/2005 3:17 PM
From reading and seeing the 'spare Burans' in the video section, when the US lost Challenger, couldn't a deal be brokered that would see the US buying into the Buran program?
We wouldn't of even entertained the possibility of dealing with the then Soviet Union as our governments, not our people, were in a state of Cold War.
Post by: rsp1202 on 10/19/2005 08:38 pm
Yes, Lockheed bought Russian RD-180 engines for Atlas V, but I believe only on the proviso that they could take up the license to manufacture them here.
Post by: Flightstar on 10/19/2005 09:15 pm
Post by: Shuttle Scapegoat on 10/22/2005 04:11 am
Post by: Flightstar on 10/22/2005 04:14 am
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Shuttle Scapegoat - 21/10/2005 11:11 PM
How much horsepower is a STS numbered at?
That's one of the fun questions which goes around from time to time. My favorite conversion which we like to use is 44,000,000 horsepower.
Post by: Rocket Guy on 10/22/2005 04:30 am
Post by: Flightstar on 10/22/2005 04:32 am
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Ben - 21/10/2005 11:30 PM
Horsepower is based on velocity, and since the Shuttle accelerates it's relative. I've seen numbers from 30 million to 100 million! That's why we use pounds/newtons of thrust.
That's why it's a fun question! ;)
Post by: SimonShuttle on 10/22/2005 11:03 am
Post by: Chris Bergin on 10/22/2005 11:07 am
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SimonShuttle - 22/10/2005 12:03 PM
Anyone got a copy of the last few minutes before launch on what happens before lift off?
I think there's more, but this is easier to read.
# Start automatic ground launch sequencer (T-9:00 minutes)
# Retract orbiter crew access arm (T-7:30)
# Start mission recorders (T-5:30)
# Start Auxiliary Power Units (T-5:00)
# Arm SRB and ET range safety safe and arm devices (T-5:00)
# Start liquid oxygen drainback (T-4:55)
# Start orbiter aerosurface profile test (T-3:55)
# Start main engine gimbal profile test (T-3:30)
# Pressurize liquid oxygen tank (T-2:55)
# Begin retraction of the gaseous oxygen vent arm (T-2:55)
# Fuel cells to internal reactants (T-2:35)
# Pressurize liquid hydrogen tank (T-1:57)
# Deactivate SRB joint heaters (T-1:00)
# Orbiter transfers from ground to internal power (T-0:50 seconds)
# Ground Launch Sequencer go for auto sequence start (T-0:31 seconds)
# SRB gimbal profile (T-0:21 seconds)
# Ignition of three Space Shuttle main engines (T-6.6 seconds)
# SRB ignition and liftoff (T-0)
Post by: GirlygirlShuttlefan on 10/23/2005 08:14 pm
Post by: Flightstar on 10/23/2005 08:29 pm
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GirlygirlShuttlefan - 23/10/2005 3:14 PM
What would happen if one SRB started and the other didn't? Can it still make it up on one, like when a plane loses an engine?
No, it would be bad, very bad. The Shuttle stack would cartwheel off the pad, into the ocean if the left SRB ignited, possbily taking part of the pad with it. If the right SRB lit and the left failed, then it would likely cartwheel into the LLC and VAB area, killing everyone in the vicinity. The Range Safety Officer would not really have enough time to self desruct the Shuttle in time to try and stop either event.
Basically, it would be extreemly bad if that ever happened. Even in the 'best' senario, the crew would die.
Post by: rsp1202 on 10/23/2005 08:35 pm
Post by: Avron on 10/24/2005 02:06 am
think the only option would be to stage on the ground in a nanosecond or two... and hope like hell ... with the SME's running she would fall forward onto the tank full of LH2 (just like the 'Twang' mid point at T-minus 3.3 secs), if and only if the the Ignited SRB went off on its own (maybe it would just rip off, if not staged)... Either way it would be bad.. very bad
Luckly is the same trusted design from 1232 AD..
Anyone know if there where redundant igniters in the SRB?.. I would be very surprised if that was not the case
Post by: realtime on 10/24/2005 02:15 am
What a horrible thread this has become. :o
Post by: Flightstar on 10/24/2005 02:36 am
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Avron - 23/10/2005 9:06 PM
I think it would just rip itself apart, somethink like what happend on the Challenger 51L, if you look at the the details returned from telemetry..
think the only option would be to stage on the ground in a nanosecond or two... and hope like hell ... with the SME's running she would fall forward onto the tank full of LH2 (just like the 'Twang' mid point at T-minus 3.3 secs), if and only if the the Ignited SRB went off on its own (maybe it would just rip off, if not staged)... Either way it would be bad.. very bad
Luckly is the same trusted design from 1232 AD..
Anyone know if there where redundant igniters in the SRB?.. I would be very surprised if that was not the case
There are four igniters in each SRB.
Post by: Flightstar on 10/24/2005 02:39 am
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realtime - 23/10/2005 9:15 PM
Aren't the hold-downs strong enough to hold her down with the SRBs going? If you didn't get positive ignition on both sides, could you cut SSMEs and wait it out?
What a horrible thread this has become. :o
Would make no difference. We release the hold down bolts before we send the signal (1/100ths of a second before) to the SRBs to fire. It's a hugely unlikely event, but I think John Young once claimed you could get off the pad and try and 'get light' on a very slow and dangerous assent before a RTLS abort and called it a "sporty ride". But that's John Young for you.
Afraid it is a non survivable event with the Shuttle having to be destroyed by the RSO (and the crew killed) or the same difference with the tearing apart of the stack.
Post by: Rocket Guy on 10/24/2005 05:13 am
The chances of an SRB not lighting are actually one of the least-likely things that can go wrong in rocketry. It's neverhappened so far as I know, and engineers like to talk about the fact that they are, quote, "SOOOOO confident" that both the SRBs will ignite that there is no worry in blowing the bolts first (they mentioned that during the silly press briefing at 114).
Post by: FransonUK on 10/24/2005 05:05 pm
Post by: Chris SF on 10/24/2005 07:11 pm
Quote
Flightstar - 23/10/2005 9:39 PM
I think John Young once claimed you could get off the pad and try and 'get light' on a very slow and dangerous assent before a RTLS abort and called it a "sporty ride". But that's John Young for you.
I think that guy could ride a donkey to LEO. What a guy. He is NASA to me.
Post by: realtime on 10/24/2005 10:18 pm
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Chris SF - 24/10/2005 3:11 PMWell said!QuoteFlightstar - 23/10/2005 9:39 PM
I think John Young once claimed you could get off the pad and try and 'get light' on a very slow and dangerous assent before a RTLS abort and called it a "sporty ride". But that's John Young for you.
I think that guy could ride a donkey to LEO. What a guy. He is NASA to me.
Post by: Orbiter Obvious on 10/25/2005 01:04 am
Post by: Avron on 10/25/2005 02:43 am
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Orbiter Obvious - 24/10/2005 9:04 PM
Ok, talking about SSMEs now. What happens if one fails, or more. Anyone got any senarios? Has one ever failed?
Define Fail, like have to be shut down, but not fall apart, in a launch, as there has been at least one test of a real failure.. On a lauch it all depends on where there is a shutdown of a SSME... but you get abort.. like Return to launch site, transatlantic site abort (TAL) and Abort to Orbit, then there are options for one engine or two engine failures (shutdowns)..
Yes it has happened.. STS-51 F "At T+645 seconds the number one engine shut down prematurely due to a sensor problem"
Post by: Shuttle Man on 10/25/2005 03:03 am
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Avron - 24/10/2005 9:43 PMQuoteOrbiter Obvious - 24/10/2005 9:04 PM
Ok, talking about SSMEs now. What happens if one fails, or more. Anyone got any senarios? Has one ever failed?
Define Fail, like have to be shut down, but not fall apart, in a launch, as there has been at least one test of a real failure.. On a lauch it all depends on where there is a shutdown of a SSME... but you get abort.. like Return to launch site, transatlantic site abort (TAL) and Abort to Orbit, then there are options for one engine or two engine failures (shutdowns)..
Yes it has happened.. STS-51 F "At T+645 seconds the number one engine shut down prematurely due to a sensor problem"
Yes, STS-51F was an ATO without a problem. Although a second SSME was being closely watched, so it was still quiet nerve wracking.
Post by: Terry Rocket on 10/26/2005 10:04 am
Post by: Chris Bergin on 10/26/2005 10:10 am
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Terry Rocket - 26/10/2005 11:04 AM
What went wrong with STS-93? I keep hearing about that one being a problem launch?
Yep.
All explained in words and video here:
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=442&posts=10
Post by: Flightstar on 10/26/2005 12:45 pm
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Chris Bergin - 26/10/2005 5:10 AMQuoteTerry Rocket - 26/10/2005 11:04 AM
What went wrong with STS-93? I keep hearing about that one being a problem launch?
Yep.
All explained in words and video here:
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=442&posts=10
That is a good link. Collins' first command.
Post by: Boris the Space Dog on 10/26/2005 02:18 pm
Post by: Flightstar on 10/26/2005 02:51 pm
The launch pad was built for the Saturn Vs and it would have cost a huge amount of cash to resituate them.
Also it is more stable for the Orbiter to ascend in a heads-down configuration - its more stable that way and it also gives the astronauts a view out their window that gives them some orientation to where the earth's horizon.
Post by: Orbiter Obvious on 10/26/2005 03:00 pm
Post by: Chris Bergin on 10/26/2005 03:01 pm
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Orbiter Obvious - 26/10/2005 4:00 PM
I didn't know that! I thought it was for some techincal aerodynamic reason How does the Shuttle actually roll, cause I see people say it doesn't use its wings on lift off.
The SRBs nozzles pivot/gimble causing the stack to twist into the roll.
Post by: Rocket Guy on 10/26/2005 07:57 pm
Post by: UK Shuttle Clan on 10/27/2005 02:00 pm
Post by: Stardust9906 on 10/27/2005 02:28 pm
Post by: UK Shuttle Clan on 10/27/2005 02:44 pm
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Stardust9906 - 27/10/2005 9:28 AM
You can find the answer to your question at http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/srb.html
Please remember some of us don't have a clue, which is why this thread is here, which is why I was asking. I can't make head or tales of that!
Post by: Flightstar on 10/27/2005 02:47 pm
Post by: newsartist on 10/27/2005 09:14 pm
Post by: FransonUK on 10/27/2005 09:27 pm
Post by: newsartist on 10/28/2005 12:57 am
The propellant is poured into each segment, much like concrete or Jello into a mold. It is then cured and hardened into something that can be handled. The exact process is probably a closely guarded company secret.
For at least the segments with the circular hole for the flame path, a plug is in the center of the casing 'mold' and that is later pulled out leaving the void. I have never read if the star-segments are molded that way or machined later. Perhaps someone else can say?
To guard against inconsistancies in the batches of propellant, two cases are loaded in matched pairs so that the thrust is equal on both sides of the stack.
I did find this interesting picture of the special dedicated railcars used to transport the segments to the Cape. Notice the wheel off the track! There may even be pictures of the segment loading elsewhere in this wbsite.
http://www.ninfinger.org/~sven/models/vault2004/ksc%20sts%20srb%20segment%20railcars/ksc-00pp-0934.jpg
Post by: realtime on 10/28/2005 02:31 am
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newsartist - 27/10/2005 8:57 PMAnd if you want to know more about "humping", you can get the straight dope here:
...
I did find this interesting picture of the special dedicated railcars used to transport the segments to the Cape. Notice the wheel off the track! There may even be pictures of the segment loading elsewhere in this wbsite.
http://www.ninfinger.org/~sven/models/vault2004/ksc%20sts%20srb%20segment%20railcars/ksc-00pp-0934.jpg
http://www.straightdope.com/classics/a2_402b.html
;)
Post by: tommy on 10/31/2005 11:42 am
Post by: Chris Bergin on 10/31/2005 11:53 am
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tommy - 31/10/2005 12:42 PM
Is it true that the Orbiter actually steers on the way up to orbit by moving its engines not its wings or rudder?
Tommy, yes they do use the engines for 'steering'. Go and have a look at some of the longer length launch videos on the video vault section.....you'll hear them mentioning "the main engines are gently 'gimbling' for a precise key hole in space for main engine cut off".
Post by: tommy on 10/31/2005 12:00 pm
Post by: Tahii on 11/01/2005 04:46 am
Post by: Shuttle Scapegoat on 11/01/2005 07:36 pm
Post by: Martin FL on 11/01/2005 09:25 pm
Post by: STS Tony on 11/01/2005 10:32 pm
Post by: Flightstar on 11/01/2005 10:36 pm
What that image is showing you is the process, note the arrows.
Post by: STS Tony on 11/01/2005 10:37 pm
Post by: SRBseparama on 11/02/2005 01:56 am
Post by: DaveS on 11/02/2005 10:27 pm
Post by: Rocket Guy on 11/02/2005 11:07 pm
Post by: norm103 on 11/03/2005 05:05 pm
Post by: FransonUK on 11/03/2005 09:03 pm
Post by: nacnud on 11/04/2005 12:08 am
Quick question, the STS was designed to service spacestations and fix satellites (I think...) why is there not a docking port internallywithin the crew quarters but only externally in the payload bay.
Post by: Flightstar on 11/04/2005 02:31 am
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nacnud - 3/11/2005 7:08 PMQuick question, the STS was designed to service spacestations and fix satellites (I think...) why is there not a docking port internallywithin the crew quarters but only externally in the payload bay.
Ironically, it was never intended primarily to be a ship that would be visting space stations, even though many of the sales pitches had it on the side of a space station.
When it was concieved, it was sold as a reusable and more economical alternative to the standard disposable stage rockets. The idea was to have a ship that could deliever payloads, in various ways, have multiple senarios while delievering, be able to retrieve payloads that had malfunctions and basically have versitility on the side of them.
If I read your post correctly, you refer to a docking port that was purposed for EVA entrance and exit to the payload cargo bay.
Why a docking port was then installed into all orbiters externally was the best solution for MIR and then ISS docking.
Post by: norm103 on 11/04/2005 02:58 am
Post by: SRBseparama on 11/04/2005 03:01 am
Post by: Rocket Guy on 11/04/2005 04:38 am
First numner is for the planned year of launch, second for the launch site (1 is KSC 2 is Vandy) and the letter was the planned mission of that year by number (A1, B2 etc).
Post by: DaveS on 11/10/2005 10:06 pm
Post by: nacnud on 11/11/2005 12:25 pm
Thanks
![]("http://upload.wikimedia.org/wikipedia/commons/thumb/8/88/Astronaut-EVA.jpg/600px-Astronaut-EVA.jpg")
MMU inspection of an orbiter, from MMU user guide (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19790008382_1979008382.pdf)
Post by: David AF on 11/11/2005 12:37 pm
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DaveS - 10/11/2005 5:06 PM
Something I have always wondered is how workers remove the red tape around the ET umbilical wells that is visivle during mating ops in the VAB? Doesn't the tape damage the tiles?
It's not tape, it's a type of paint that just wipes off when they mate to the ET (At least that is what I was told).
Post by: MKremer on 11/11/2005 01:00 pm
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nacnud - 11/11/2005 7:25 AM
Q: Will Manned Maneuvering Units (MMU) ever be used again, and if not why not?
Thanks
I seriously doubt it. The Shuttle MMUs were developed up through the early 80's before Challenger, back when "lots of cheap flights" were still being envisioned for things like routine satellite deployments and recoveries.
After Challenger, and the Air Force pullout, and after realizing how expensive and valuable the Shuttles (and her crews) are, the "cheap space moving van" concept didn't make sense anymore. There wasn't much need for untethered spacewalks from that point on, too, because it was found that the Shuttle arm and tethered EVA workers could do as much or more than a free-floating astronaut.
There's a good history of MMU and development here:
http://history.nasa.gov/SP-4219/Chapter13.html
Yet the MMU has not been used since 1984. There are several reasons for this. First, most extravehicular activities were effective without use of the MMU. Tethers, safety grips, hand bars, and other restraints allowed astronauts to work in the open cargo bay. Furthermore, the maneuverability of the Space Shuttle itself and the utility of the shuttle's robotic manipulator arm had proved capable of rescuing satellites-the primary function for which the MMU had been designed. The orbiter could be piloted with such accuracy that on mission 41-B, for example, commander Vance D. Brand piloted the Challenger into position so that McCandless on the manipulator arm could grab a foot restraint that had broken loose and floated away from the orbiter. On flight 41-C, the MMU failed to achieve mechanical mating to the Solar Max satellite, but the orbiter and manipulator arm recovered the satellite. On the Discovery mission, 51-A, commander Henry W. Hartsfield operated the remote manipulator arm to knock ice off a waste-water port, the ice being a reentry hazard. This sort of contingency was a potential MMU activity, but the manipulator arm solved the problem.
Another reason for lack of use of the MMU was the Challenger accident. In January 1986 the Challenger exploded 73 seconds after launch. The crew of seven, the spacecraft, and the payload were lost. That accident initially prompted a suspension of space flights that lasted into September 1988. The accident and resulting investigations also prompted new safety rules that would require expensive changes to the existing MMU, changes pending both a customer and a mission for the MMU. Still another reason for not using the MMU has been the lack of a new user with adequate funding and appropriate mission. Finally, since the Space Station is still under discussion, the Space Shuttle remains the main space human flight program of the United States. The MMU is not necessary to its operations.
Post by: Bruce H on 11/11/2005 02:49 pm
Post by: nacnud on 11/11/2005 02:58 pm
Post by: Flightstar on 11/11/2005 03:12 pm
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nacnud - 11/11/2005 9:58 AM
That what I was wondering, maybe the HSM could use a couple.
That'll be the same as you saw with the Gap Fillers. I know you will know this, but for the benefit of others, Hubble will be captured and secured in the Cargo Bay and access will be from the end of the Robotic Arm for work higher up the telescope than is viable from a tether in the Cargo Bay area.
Post by: nacnud on 11/11/2005 03:25 pm
Post by: Flightstar on 11/11/2005 04:16 pm
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nacnud - 11/11/2005 10:25 AM
What about removing gap fillers on a HSM? /pokeing dead horse
Expect the problem with gap fillers to be no more following the new bonding solution that is being implemented as we speak in the OPFs :)
Post by: MKremer on 11/11/2005 04:25 pm
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nacnud - 11/11/2005 10:25 AM
What about removing gap fillers on a HSM? /pokeing dead horse
Too risky to maneuver that close to the tiles, especially without a stable platform to use as an 'anchor' for pulling, pushing, or cutting forces.
Post by: FransonUK on 11/12/2005 04:02 pm
Post by: Terry Rocket on 11/16/2005 11:13 am
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FransonUK - 12/11/2005 11:02 AM
What exactly do they do on a HSM?
I'll field this one :)
They grab hold of the telescope with the Shuttle robotic arm and hold it in place in the cargo bay. They they replace the batteries and anything else that needs doing on it. Pretty simple, but they have to be careful.
Post by: nethegauner on 11/16/2005 11:19 am
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Terry Rocket - 16/11/2005 1:13 PMBut before they service the telescope, it is attatched to the FSS cradle in the aft payload bay. The RMS is then used to move ORUs and astronauts around.QuoteFransonUK - 12/11/2005 11:02 AMI'll field this one :)
What exactly do they do on a HSM?
They grab hold of the telescope with the Shuttle robotic arm and hold it in place in the cargo bay. They they replace the batteries and anything else that needs doing on it. Pretty simple, but they have to be careful.
Post by: Mark Max Q on 11/17/2005 01:12 pm
Post by: MKremer on 11/17/2005 03:41 pm
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Mark Max Q - 17/11/2005 8:12 AM
I've always been interested in how the Orbiter stays on the side of the ET during launch. What are the attachments made of to keep the Orbiter from falling off. Seperation seems so simply.
Basically, it's held on by 3 very strong bolts.
If you start reading here: Orbiter/External Tank Separation System you'll get detailed info about the ET attachments and umbilicals, and how separation occurs. It looks a whole lot simpler than it really is. :)
Post by: GirlygirlShuttlefan on 11/17/2005 04:34 pm
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MKremer - 17/11/2005 10:41 AMQuoteMark Max Q - 17/11/2005 8:12 AM
I've always been interested in how the Orbiter stays on the side of the ET during launch. What are the attachments made of to keep the Orbiter from falling off. Seperation seems so simply.
Basically, it's held on by 3 very strong bolts.
If you start reading here: Orbiter/External Tank Separation System you'll get detailed info about the ET attachments and umbilicals, and how separation occurs. It looks a whole lot simpler than it really is. :)
Pretty baffling, but if I get stuck I'll ask what some of those things mean. NASA pages don't tend to space things out very well ;)
Post by: Avron on 11/18/2005 03:04 am
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GirlygirlShuttlefan - 17/11/2005 12:34 PM
Basically, it's held on by 3 very strong bolts.
...
Pretty baffling, but if I get stuck I'll ask what some of those things mean. NASA pages don't tend to space things out very well ;)
short summary:
"The forward structural attachment consists of a shear bolt unit mounted in a spherical bearing. The bolt separates at a break area when two pressure cartridges are initiated. The pressure from one or both cartridges drives one of a pair of pistons to shear the bolt, "etc...
The aft structural attachment consists of two special bolts and pyrotechnically actuated frangible nuts that attach the external tank strut hemisphere to the orbiter's left- and right-side cavities. At separation the frangible nuts are split by a booster cartridge initiated by a detonator cartridge. "
Post by: kraisee on 11/18/2005 03:30 am
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MKremer - 17/11/2005 11:41 AM
Basically, it's held on by 3 very strong bolts.
The bolts look something like this:
![]("http://68.205.251.208/Public/ShuttleBolt.jpg")
If I recall correctly that particular one is a nose attachment bolt for the Orbiter, but don't quote me :)
The red caps on either end are the bolt-head, just next to these, at both ends, go a ring of shaped charges designed to cut through the main core of the bolt. At separation (for SRB's too) the shaped charges are detonated, and the bolt is cut at the head. The bolt-head itself is then flung off and is caught in a box designed to trap it and ensure it does no damage (these "Bolt Catchers" you may recall hearing about during the Columbia Accident Investigation).
Anyhow, each of the separation bolts has a completely independant backup system at the other end of the bolt including detonator, charge and complete wiring harness to ensure the bolt can be severed at that end instead about 1/10th of a second later.
And just to help you collect useless factoids - you might be interested to note that Endeavour on STS-108 had a major problem with the primary charges failing completely for SRB separation. None of the primary SRB separation bolts blew at all - potentially a very dangerous situation. Luckily though, the backup system took over and blew all the bolts successfully and the launch continued safely. The problem was later traced to faulty wiring.
Ross.
PS - Avron may be right about the explosive charges pushing a piston which slices through the bolt instead. I'm not 100% certain which technique is used.
Post by: Chris Bergin on 11/18/2005 09:34 am
Post by: nethegauner on 11/18/2005 09:44 am
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kraisee - 18/11/2005 5:30 AMHey, I know where You took that shot. In the shuttle pavillion at the KSC visitor center, right? I was there too a while ago and had the opportunity to grab this thing and actually lift it. Boy, that was heavy! Amazing, truly amazing ...QuoteMKremer - 17/11/2005 11:41 AM
Basically, it's held on by 3 very strong bolts.
The bolts look something like this: [...]
Post by: Firestarter on 11/18/2005 10:52 pm
If this is such a dangerous thing, why isn't there more concern about the SRB Sep when the separation literally blows a load of foam away with the explosion?
Post by: DaveS on 11/18/2005 11:10 pm
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Firestarter - 19/11/2005 12:52 AMActually, the Booster Seperation Motors(BSMs) only scorch the ET, I don't believe that they're powerfull enough to cause substantial foam loss. Take a look on this photo of ET-121, following its ride into space during STS-114: http://spaceflight.nasa.gov/gallery/images/shuttle/sts-114/hires/s114e5002.jpg
Shuttle Foam Debris:
If this is such a dangerous thing, why isn't there more concern about the SRB Sep when the separation literally blows a load of foam away with the explosion?
You can clearly see the scorching from the BSMs on the intertank and lower part of the LOX tank, but no substantial foam loss.
Post by: MKremer on 11/19/2005 12:46 am
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Firestarter - 18/11/2005 5:52 PM
Shuttle Foam Debris:
If this is such a dangerous thing, why isn't there more concern about the SRB Sep when the separation literally blows a load of foam away with the explosion?
The booster separation motors' exhaust pressure is pretty insignificant compared to the aerodynamic pressures and forces on the foam during max-Q and trans-sonic acceleration during ascent. Any weak foam areas would have already been ripped off by the time the SRBs separated.
The visible scorching on the ET is mainly due to the heat and exhaust residue of the BSMs.
Post by: kraisee on 11/19/2005 06:39 pm
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DaveS - 18/11/2005 7:10 PMQuoteFirestarter - 19/11/2005 12:52 AMActually, the Booster Seperation Motors(BSMs) only scorch the ET, I don't believe that they're powerfull enough to cause substantial foam loss. Take a look on this photo of ET-121, following its ride into space during STS-114: http://spaceflight.nasa.gov/gallery/images/shuttle/sts-114/hires/s114e5002.jpg
Shuttle Foam Debris:
If this is such a dangerous thing, why isn't there more concern about the SRB Sep when the separation literally blows a load of foam away with the explosion?
You can clearly see the scorching from the BSMs on the intertank and lower part of the LOX tank, but no substantial foam loss.
Actually, a number of engineers I have spoken with believe that the SRB separation motors were the "straw that broke the camels back" for the big foam chunk that came off the PAL Ramp on STS-114.
That foam did survive Max-Q and made it all the way into very very thin atmosphere indeed. It is believed that the foam was loosened on the way up, but stayed attached. It is believed that the blast from the SRB sep motors was enough to finally jar the last bit loose completely and that's why it fell away only seconds after the separation event.
Ross.
PS - Yes nethegauner, that's exactly where that pic came from. They do a cool little presentation in there.
Post by: MKremer on 11/19/2005 07:39 pm
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kraisee - 19/11/2005 1:39 PMSo they seem pretty sure it was from the motor exhaust pressure itself, and not something like sharp vibration transients from the separation pyros?
It is believed that the foam was loosened on the way up, but stayed attached. It is believed that the blast from the SRB sep motors was enough to finally jar the last bit loose completely and that's why it fell away only seconds after the separation event.
Post by: Shuttle Scapegoat on 11/20/2005 04:33 pm
Post by: realtime on 11/20/2005 05:32 pm
Quote
Actually, a number of engineers I have spoken with believe that the SRB separation motors were the "straw that broke the camels back" for the big foam chunk that came off the PAL Ramp on STS-114.Sounds like there's precious little "engineering margin" there. No way something that just barely makes it to orbit on a good day should be a structural element like a PAL ramp.
Post by: newsartist on 11/21/2005 01:02 am
It is exactly the same as the stacks on oil and chemical plants. In this case, it burns off excess hydrogen in a controlled manner, to prevent any possibility of a powerful free-air explosion. It has been mentioned elsewhere, that another fuel is added to the flame so it can be seen easily, confirming that it is working.
Post by: Avron on 11/21/2005 03:18 am
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realtime - 20/11/2005 1:32 PMQuoteActually, a number of engineers I have spoken with believe that the SRB separation motors were the "straw that broke the camels back" for the big foam chunk that came off the PAL Ramp on STS-114.Sounds like there's precious little "engineering margin" there. No way something that just barely makes it to orbit on a good day should be a structural element like a PAL ramp.
Totaly agree.. but what do we see, at MAF.. more foam structural elements..:(
Post by: kraisee on 11/22/2005 11:24 pm
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Shuttle Scapegoat - 20/11/2005 12:33 PM
On some of the launch videos you can see a flame tower to the side of the launch pad, like an oil rig. What is that and what does it do?
Well spotted. Not many people notice that.
What you're seeing is the thing called the "Flare Stack". When a Shuttle is being fuelled on the pad, some of the liquid Hydrogen propellant warms up sufficiently to evaporate back into a gas inside the tank. This Hydrogen gas is highly explosive (remember what happened to the Hindenberg) so it needs to be removed and safely disposed of.
The gas is vented from the External Tank, piped a fairly long way from the pad to the "Flare Stack", and is then burned safely in the atmosphere.
Ross.
Post by: Justin Space on 11/23/2005 12:07 pm
Post by: MKremer on 11/23/2005 04:10 pm
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Justin Space - 23/11/2005 7:07 AM
Does the gas come out of the top with that arm that swings over to the pad with two minutes to go?
That's the oxygen vent arm for boil off from the LOX tank.
Post by: Shuttle Scapegoat on 11/24/2005 12:54 am
Post by: MKremer on 11/24/2005 04:20 am
Post by: Orbiter Obvious on 11/27/2005 03:15 am
Post by: Flightstar on 11/27/2005 03:55 am
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Orbiter Obvious - 26/11/2005 10:15 PM
After the fun of the SpaceX attempted launch today, I was wondering how they avoid problems with burn off of the LOX in the ET. Do they simply keep toping it up. I'd expect KSC isn't like to run out of the stuff aswell?
Remember, they didn't suffer a surprise in the boiloff, it was a fault with what will be their version of "stable replenishment."
To give you some info and I'll keep it as readable as possible. We pump in more than half-million gallons of super-cold liquid oxygen (LOX) and liquid hydrogen (LH2) into two tanks inside the ET, seperated by a intertank (not a tank itself, just part of the ET structure two thirds up inbetween the two tanks.
143,000 gallons of liquid oxygen chilled to minus 298 degrees Fahrenheit goes into the LOX tank (the top third) and 385,000 gallons of liquid hydrogen chilled to minus 423 degrees Fahrenheit into the LH2 tank.
The tanking process takes three hours and is pumped from storage spheres at the pad, through feed lines to the mobile launcher platform, into Columbia's aft compartment and finally into the ET.
Now you can't leave it at that, because the cryogenic nature of the oxidizer and propellant means they boil off. It's not a major boil off rate on the Shuttle ET as its highly insulated (the imfamous foam shell) bu you have to keep slowely pumping to keep the ETs topped off right up until the final couple of minutes before launch.
If something stops you from doing that, as with the Falcon I and you are delayed while you try and fix it, all the time you're losing quality in your tank and the more you'll need to top it up when you've fixed the problem. SpaceX simply ran out of LOX.
There's also pressurization with Hellium, which they also need to go and get more of, but to answer your question on "stable replenishment" that is how we do it with the Shuttles.
Post by: kraisee on 11/27/2005 05:12 am
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realtime - 20/11/2005 1:32 PMQuoteActually, a number of engineers I have spoken with believe that the SRB separation motors were the "straw that broke the camels back" for the big foam chunk that came off the PAL Ramp on STS-114.Sounds like there's precious little "engineering margin" there. No way something that just barely makes it to orbit on a good day should be a structural element like a PAL ramp.
I wholeheartedly agree, but the PAL ramp "as designed" should be okay.
The problem was that during application of the foam on that particular tank, there was a problem, and a portion of the ramp foam had to be removed and replaced before flight. It seems that, for some reason, the process of removing foam and replacing it with new foam caused a structural weakness to the bonding, and it is precisely that segment of foam which was loosened during the ascent.
Now, I know a *LOT* of previous tanks had sections of foam replaced routinely, and I'd love to have access to the various records NASA has, to see if there is any correlation between foam replacement locations and known foam loss on previous flights. I suspect there is something there to be found if you look hard enough, but I have no evidence to back that guess up.
Now though, the tank due to be used on STS-121 in May has turned up with 9 new cracks in the foam - which raises all sorts of new questions.
I believe that tank with the new problems is actually the one Atlantis was mounted to inside the VAB when Columbia was lost, and also the same tank Discovery was mounted to originally last year before she had to be de-stacked due to fuel sensor problems. That tank has been around the block already - and some, so perhaps those new cracks in the foam is just the tank showing signs of old-age.
Personally I think its all a waste.
Ross.
Post by: Chris Bergin on 11/27/2005 11:58 pm
Here are the three images we gained from a MAF source who noted the prior-to-shipping work on ET-121's PAL ramp area.
Note the images are untouched and came with the text already on the images. We used them as part of this article: http://www.nasaspaceflight.com/content/?id=3308 - and in the Debris Update thread on the Discovery section of the forum.
Post by: Chris Bergin on 11/28/2005 12:09 am
Post by: STS Tony on 11/28/2005 02:06 am
And a question to add, seen as it's a Q and A thread :) Had it of not been for this area of foam coming off the ramp, would we never have had to send the ETs back, causing the delay? I know there's been other things like the gap fillers, but this is just about then having to send the tanks back to a factory that just before had the problem with Kartina causing serious distruption.
Post by: kraisee on 11/28/2005 04:31 am
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STS Tony - 27/11/2005 10:06 PM
Thanks, I hadn't seen those images, but I also haven't been through the full 18 pages of the debris thread, so that'll explain it. Very interesting if only for the area pointed out being in the same area and size of what came off.
And a question to add, seen as it's a Q and A thread :) Had it of not been for this area of foam coming off the ramp, would we never have had to send the ETs back, causing the delay? I know there's been other things like the gap fillers, but this is just about then having to send the tanks back to a factory that just before had the problem with Kartina causing serious distruption.
The tank we saw on Discovery's first rollout was going back to Michoud anyway because it had the internal problems with the fuel cut-off sensor.
The next tank which was going to fly with Atlantis a month or so later was already at KSC when Discovery was launched. I believe it did go back purely because of that foam loss event on STS-114.
And I seem to recall hearing from somewhere that Michoud actually had a further 12 or 14 ET's in various stages of construction at that time too.
Ross.
Post by: Chris Bergin on 11/29/2005 12:27 am
ET-120 (Original ET for STS-114) had issues with its LH2 diffuser. The was the first and only ET to have the newly designed by MSFC double weave diffuser, which was not a popular choice among USA ET mechs. At the time they claimed the large amount of cycles (over-cycled) on the prepress was the fault of this double weave diffuser.
ET-121 (Atlantis' ET, which then became Discovery's ET on STS-114) had the single weave, but ironically also cycled high, right up to the limit (very close to an abort - one cycle away - with the SSMEs already buring at full thrust).
MAF do have all those ETs as noted, but have lost one right down the line due to Karina damage. Will still fly, but needs repair work.
Post by: MKremer on 11/29/2005 12:52 am
Quote
Chris Bergin - 28/11/2005 7:27 PMWas that the one hit by the falling roof materials? Did they find it was a lot more serious than just some external foam 'dings' and scuffs like they originally reported?
MAF do have all those ETs as noted, but have lost one right down the line due to Karina damage. Will still fly, but needs repair work.
Post by: Chris Bergin on 11/29/2005 01:15 am
Quote
MKremer - 29/11/2005 1:52 AMQuoteChris Bergin - 28/11/2005 7:27 PMWas that the one hit by the falling roof materials? Did they find it was a lot more serious than just some external foam 'dings' and scuffs like they originally reported?
MAF do have all those ETs as noted, but have lost one right down the line due to Karina damage. Will still fly, but needs repair work.
Yes, that's the ET in question. As of the 21st of Nov, they were still doing assessments on it. It was cosmetic damage, but given how much needs to be resprayed etc. added to the issues of re-working ET TPS foam post ET-121, it's the one ET that's classed as damaged with the need for repair.
Post by: MKremer on 11/29/2005 01:26 am
Post by: Bruce H on 11/29/2005 02:43 am
Quote
MKremer - 28/11/2005 8:26 PM
I also read that the damage was opposite the Orbiter side, so I would imagine any foam repairs won't need to be as critically 'perfect' as they would be if the damage were on the same side.
One would assume that, but with the way foam loss is being viewed and reported by the media, Wayne Hale could say there was no loss in areas of concern, but some on the opposite side and the press would blow it up as another problem, no matter how many times you explain it.
I'm talking about the press that doesn't understand, not the main space sites, but its the big daily papers that drive perception.
Short answer. I would simply not risk flying it when they have other non-affected ETs.
Post by: David AF on 11/29/2005 03:27 am
Post by: UK Shuttle Clan on 11/29/2005 07:42 pm
Post by: darkenfast on 12/01/2005 10:05 am
Most coverage naturally follows the vehicle, so I've always been curious about the conditions at the pad immediately following a lift-off. Thanks!
Post by: Spacely on 12/01/2005 04:08 pm
How often do they repaint the Shuttles? In some launch pad pics, they're gleaming white; in others, they're pretty dirty.
Post by: Rocket Guy on 12/01/2005 05:15 pm
But seriously, to learn about it, the Shuttle's are 100% covered in tiles (all the black and gray; the gray is RCC panel) and thermal blankets (most of the white). They have replaced much of what used to be white tiling with white thermal blankets; and in addition, they replace tiles and blankets after missions if they took enough wear and tear such that they need to be.
Up close the Orbiters always look pretty dirty from their many years of use and reentry heating. Only the newly added tiles and blankets may appear to gleam. New tiles have a hard semigloss coating on the outside which can shine in the sun.
Post by: Spacely on 12/01/2005 05:45 pm
Post by: SimonShuttle on 12/01/2005 05:57 pm
Imagine a boy scout in Florida asking if there's any cars that want washing for $2s and they point at a dirty 100 foot long space ship :)
Post by: Chris Bergin on 12/01/2005 06:53 pm
Quote
UK Shuttle Clan - 29/11/2005 8:42 PM
Do all the new ETs coming from MAF to KSC have the new or old diffuser?
MAF guy says they are sticking with the old one (single weave), but he's checking. Will update that later.
Post by: Shuttle Scapegoat on 12/01/2005 07:54 pm
Quote
Ben - 1/12/2005 12:15 PM
They're not painted :-)
But seriously, to learn about it, the Shuttle's are 100% covered in tiles (all the black and gray; the gray is RCC panel) and thermal blankets (most of the white). They have replaced much of what used to be white tiling with white thermal blankets; and in addition, they replace tiles and blankets after missions if they took enough wear and tear such that they need to be.
Up close the Orbiters always look pretty dirty from their many years of use and reentry heating. Only the newly added tiles and blankets may appear to gleam. New tiles have a hard semigloss coating on the outside which can shine in the sun.
Thanks, I always through they had been painted black and white!
Post by: DaveS on 12/01/2005 07:55 pm
Post by: Martin FL on 12/02/2005 05:27 pm
http://forum.nasaspaceflight.com/forums/forum-view.asp?fid=25
Post by: Rocket Nut on 12/19/2005 12:17 am
Quote
Do Shuttles Dream - 16/10/2005 11:22 PMQuoteChris Bergin - 16/10/2005 3:32 PMQuoteOrbiter Obvious - 16/10/2005 9:24 PM
Would it be ok to ask for some of the likes of MECO to be explained in the words those letters stand for?
Sometimes you'll see it mentioned, such as MECO, just got to look out for it and associate. However, here's a few reeled off (one's you might see a lot of around these parts) as reference.
STS = Space Transportation System
ET = External Tank
OV = Orbiter Vehicle (such as OV-103 is Discovery, 04 is Atlantis, O5 is Endeavour)
SRB = Solid Rocket Booster
OMS = Orbital Maneuvering System
RCS = Reaction Control System
MPL = Mobile Launch Platform (Rides on the Crawler Transporter, Shuttle Stack goes on top of the MLP).
VAB = Vehicle Assembly Building
MECO = Main Engine Cut Off
SSME = Space Shuttle Main Engine
MAF = Michoud Assembly Facility
MSFC = Marshall Space Flight Center
KSC = Kennedy Space Center
RLV = Reusable Launch Vehicle
LOX = Liquid Oxygen
LH2 = Liquid Hyrogen
ECO = Engine Cut Out (sensor)
If anymore pop into my head, or the question is asked, I'll edit and add here.
Thanks. Most message boards laugh you off the forum for not knowing all that.
Sorry for the long quote, couldn't cut it down without killing the context...
When I started working on my first NASA contract, the first thing my boss gave me was a book of NASA acronyms. Hundreds of pages of acronyms. It was months before I was able to communicate comfortably with some of the NASA people. Now, I can think in acronyms. If I have to translate it into the individual words, it is more difficult. For example, if someone says SSME, I see in my mind the actual hardware. It would take me longer to break it down into Space Shuttle Main Engine. When I see the hardware, it is the SSME...not the Space Shuttle Main Engine. It's like learning a foreign language...pretty soon, you begin to think in that new language.
I have seen lots of documentation that has sentences where the majority of words were acronyms. Some of the acronyms were composed of several acronyms within the acronym. I can't really come up with any off the top of my head right now. I still have that acronym book around here somewhere...
Cheers,
Larry
Post by: RoadRunner on 12/19/2005 08:15 am
What is the meaning of the term "Press" as in "Press to MECO", "Single engine Press 104", etc ?
I know that MECO = Main Engine CutOff. I know that the calls are the various boundaries between abort or operational modes, but what I am unsure of is the meaning of "Press". Is this an instruction to the orbiter crew to press a button ? Or is it short for "Pressure" ?
I'm asking this because it appears to me that MECO doesn't happen immediately following the "Press to MECO" call... and I've never heard the call "Press to throttle up". It seems to me that "Press" means something specific, other than "Okay crew, push this button..."
Am I just daft ?
The RoadRunner..
Post by: DaveS on 12/19/2005 08:36 am
Post by: Stardust9906 on 12/19/2005 09:48 am
Post by: RoadRunner on 12/19/2005 10:30 am
Quote
Stardust9906 - 19/12/2005 10:48 AM
Press to MECO means that the vehicle can still reach the planned MECO should one engine fail.
Yeah cheers, but it doesn't really help me much.. I've a basic idea as to what each of the boundary calls refers to. It's this word 'Press' which I am querying. I apologise for any ambiguity in my original post as I was trying to make that point clear.
I have since found an explanation which I will paste here and reference.
------------------
104% is the "nominal" engine setting used now (and why it's > 100% is a story for another time...). "Press" is used as in "press on..." which for the non-english as a first language speakers is a phrase meaning "continue".
------------------
Found: http://orbit.m6.net/v2/read.asp?id=25471
This sounds plausible, sort of. Press (on) to MECO, Press (on) to ATO - Yeah, makes sense.
Single engine press (on) to 104 ?? Not really.
Can anyone confirm or deny this explanation and give me a solid reference ?
Thanks.
The RoadRunner..
Post by: DaveS on 12/19/2005 10:40 am
Post by: psloss on 12/19/2005 11:26 am
http://science.ksc.nasa.gov/shuttle/countdown/count.html
It's a bit old and heavily edited, but still somewhat useful for following the last parts of a shuttle count...
Philip Sloss
Post by: psloss on 12/19/2005 11:40 am
Quote
RoadRunner - 19/12/2005 6:30 AMThis site was referred to in the link you posted; it's the best overall ascent reference I've found on the Internet:
Can anyone confirm or deny this explanation and give me a solid reference ?
http://www.theandyzone.com/launchzone/launchzone.htm
(The calls you refer to are similar in nature, but indicate different engine failure modes: "press to ATO" implies a single engine failure while "single engine press..." implies a two-engine failure.)
(Edit: saw your original post...the throttle up call is "go at throttle up" and is made after the engines have throttled up. The "press" calls are somewhat anticipatory in their syntax but used to indicate abort boundaries.)
Philip Sloss
Post by: RedSky on 12/19/2005 11:50 am
Quote
RoadRunner - 19/12/2005 5:30 AMQuoteStardust9906 - 19/12/2005 10:48 AM
Press to MECO means that the vehicle can still reach the planned MECO should one engine fail.
It's this word 'Press' which I am querying. I apologise for any ambiguity in my original post as I was trying to make that point clear.
I have since found an explanation which I will paste here and reference.
------------------
"Press" is used as in "press on..." which for the non-english as a first language speakers is a phrase meaning "continue".
------------------
This sounds plausible, sort of. Press (on) to MECO, Press (on) to ATO - Yeah, makes sense.
Single engine press (on) to 104 ?? Not really.
Can anyone confirm or deny this explanation and give me a solid reference ?
Thanks.
The RoadRunner..
You got it right regarding "press" as being a shortened form of the english term "press on", basically meaning to continue. However, there is a slight added connotation: To say "press on" implies to continue through some form of adversity, e.g. through some situation that wasn' t as expected and is making things more difficult to accomplish the goal.
The exact meaning of all these launch abort "calls" are all well known to the crew, since they are from a script marking time points (well, required energy points in the ascent) and are not improvised or made up each time. A lot of implied words might be missing to keep it short. Sometimes, watching or listening to a launch, the NASA announcer will sort of interpret these calls for the viewing audience.
I haven't found a reference regarding the other abort call you mentioned, but is it really "... press to 104", or simply "Single engine press 104"? I recall the accouncer saying the meaning of this was:
Single engine press (on) (to MECO) (with full rated thrust of) 104 (% ).
Since from the earlier calls... we know that the "to MECO" is still implied, but dropped now to keep the call short. The "104" is basically adding the whole concept of: "the goal (a safe orbital velocity) can still be reached with that single remaining engine AS LONG AS it runs at its full rated thrust of 104 percent".
(as to why full thrust is 104% instead of 100%... that's a whole story in itself).
Post by: Chris Bergin on 12/19/2005 12:22 pm
Quote
psloss - 19/12/2005 12:40 PM
(Edit: saw your original post...the throttle up call is "go at throttle up" and is made after the engines have throttled up. The "press" calls are somewhat anticipatory in their syntax but used to indicate abort boundaries.)
I'm glad this has been mentioned - for years it caught me out.
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=656&start=1 - is on the flight deck of Endeavour and you can hear the crew calls, such as "Feels good", as she throttles, then the confirmation, then the call from Houston "Endeavour, go at Throttle Up".
Post by: psloss on 12/19/2005 12:26 pm
Philip Sloss
Post by: Chris Bergin on 12/19/2005 12:38 pm
STS-51F is the video you kindly allowed us to use. On that, the call is for Challenger to "Press to ATO", in case they need to, in preparation of.
Then you hear they have the centre engine down, which Houston reacts with "Challenger, Houston. Abort ATO".
Best example I can think of.
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=713&start=1
Post by: RoadRunner on 12/19/2005 02:48 pm
To Philip Sloss:
Yep, I've been reading the 'andyzone' document. Although informative, 'press' wasn't really explained (at least not from what I've read so far and I've read up to and including RTLS aborts - I've tried flying a few of them - heck !!!).
My 'press to throttle up' comment was a bit tongue in cheek. I was trying to point out that this word 'press' doesn't seem to be an instruction to literally press a button.
Now, just to be clear on something you've said here:
the throttle up call is "go at throttle up" and is made after the engines have throttled up.
The initial ground-to-air call 'go at throttle up', is made AFTER the engines have throttled back up (out of the throttle bucket).
There is then an air-to-ground acknowledgement - "Roger, go at throttle up".
This is what I understood from your post.
As opposed to the ground-to-air call being made as an instruction to the crew to throttle up. The crew then throttle up and acknowledge air-to-ground, 'Roger, go at throttle up.'
The throttle is controlled by the on-board flight computers, yes ? There would be no need for the INSTRUCTION, from ground-to-air: 'Throttle up'.
I'm sorry if this sounds disjointed, but I just want to make sure that I am clear on that point, and that there is no ambiguity in my mind as to what that call means and when/why it's given - Not that my initial query has anything at all to do with that call, it was purely about the use/meaning of the word 'press'.
Knowing that the SRBs are kicked off when their pressure drops below 50psi and that NASA have been known to use the term 'press' to refer to 'pressurization' ('Cabin re-press valve' and other such terms I've heard here and there), I thought that maybe 'press' in the context of the abort calls meant pressure (I'm no rocket-scientist).
Thus, single engine press to ATO (for example) would mean that there is still enough pressure for one engine to deliver enough delta-V to achieve Abort-To-Orbit.
I'd pretty much worked out that 'press' wasn't an instruction to press a button (although I had not totally ruled out the possibility that it may be) and besides the 'pressure' theory, I could not determine what else this word might mean.
To RedSky:
Aha. The added connotation... Yes, now that really does make sense... I should have realised that much sooner. Pressing on is just that little bit more than 'continuing' and does imply adversity.
You had me hunting about in my previous posts..... and..... you are correct. When I wrote : Single engine press (on) to 104
I should have written: Single engine press (on to) 104.
I wasn't paying proper attention to what I was typing.
The implication of 'to MECO' which has been dropped to abbreviate the call, makes sense.
To Chris:
I've downloaded the video to which you posted the link and I shall get stuck into that between making this post and my next job (it's now dark enough for me to fly (virtual) Discovery home :D) .
----
I'm sorry if I've caused some confusion as to exactly the point of my question, but it seems that the general concensus of opinion is that 'press' in the context of our abort calls means 'to press on' rather than 'press a button' or 'you have enough pressure'.
I've heard those calls time and time again but was never quite sure what 'press' meant.
So, unless anyone else contests this explanation and offers another explanation and/or reference, I'll consider my question answered and thank you all very much for your efforts.
Thanks again, peeps.
The RoadRunner..
Post by: Flightstar on 12/19/2005 03:06 pm
Quote
RoadRunner - 19/12/2005 9:48 AM
Now, just to be clear on something you've said here:
the throttle up call is "go at throttle up" and is made after the engines have throttled up.
The initial ground-to-air call 'go at throttle up', is made AFTER the engines have throttled back up (out of the throttle bucket).
There is then an air-to-ground acknowledgement - "Roger, go at throttle up".
This is what I understood from your post.
As opposed to the ground-to-air call being made as an instruction to the crew to throttle up. The crew then throttle up and acknowledge air-to-ground, 'Roger, go at throttle up.'
The throttle is controlled by the on-board flight computers, yes ? There would be no need for the INSTRUCTION, from ground-to-air: 'Throttle up'.
Yes. The Shuttle is flying herself. The Flight Computers are controllings the SSMEs telling them what they want, with the SSMEs then talking back to the flight computers, who chat and vote amongst themselves on how it's all going. It's all very clever, but I'm not a computer man. But imagine each SSME is a company employee of Shuttle Inc, and the Flight computers are a company board of Shuttle Inc. Each SSME person has to continually report to the Board, who hold the ultimate decision. If an SSME employee has a problem, they report to the board immediatly, who then vote amoungst themselves to make an instant decesion and order that SSME employee to do as they say.
SSME employees can vote too, but I don't want to complicate this.
The Pilot and Commander are literally sitting there reading those conversations through the readouts. Mission Control at JSC are seeing the same conversations via their readouts via the downlink.
So the flight computers order the SSMEs to throttle down, and then throttle up. No one else is involved. What you hear is the astronaunts comfirming what they are reading and feeling. JSC see their readouts and call the Shuttle "Go" at Throttle Up is JSC confirming they are seeing it go to plan, and visa versa for the Crew confirming "Roger, Go at Throttle" (I confirm, we have throttled up).
No buttons are pressed.
Pre-Press is pre-pressurization.
Press to ATO for example is the same as "Prepare....." and that does involve potential pressing of buttons, moving of switches. I will try and find you an image of the abort switche.
Post by: psloss on 12/19/2005 03:24 pm
Quote
RoadRunner - 19/12/2005 10:48 AMThe purpose for some of the calls differs and some calls have been added/deleted over the years.
The initial ground-to-air call 'go at throttle up', is made AFTER the engines have throttled back up (out of the throttle bucket).
There is then an air-to-ground acknowledgement - "Roger, go at throttle up".
This is what I understood from your post.
As opposed to the ground-to-air call being made as an instruction to the crew to throttle up. The crew then throttle up and acknowledge air-to-ground, 'Roger, go at throttle up.'
The throttle is controlled by the on-board flight computers, yes ? There would be no need for the INSTRUCTION, from ground-to-air: 'Throttle up'.
I'm sorry if this sounds disjointed, but I just want to make sure that I am clear on that point, and that there is no ambiguity in my mind as to what that call means and when/why it's given - Not that my initial query has anything at all to do with that call, it was purely about the use/meaning of the word 'press'.
The "go at throttle up" call seems to me to be an informational call as well as a way to do a quick communications check -- similar to the crew-initiated "roll program" call after liftoff. Assuming everything is working, both the crew and the ground are already aware that these things are happening or have happened. At the same time everybody is busy, so I don't think anyone wants to be "chatty" during ascent.
(During the first few test flights, there was an additional call -- "go at 40" [seconds].)
Regarding "Pc < 50", that doesn't separate the boosters, it starts the separation sequence in the orbiter computers; from the Andy Zone reference:
http://www.theandyzone.com/launchzone/stsasct1.htm
Quote
After load relief is complete, the shuttle flies the rest of the first stage guidance table...velocity, pitch, roll, yaw...over and over again until SRB Separation occurs, controlled by the SRB SEPARATION SEQUENCER.
The SRB SEPARATION SEQUENCER runs during all of first stage. This software monitors pressure inside the solid rocket boosters. When the pressures on both SRB's fall below 50 psi, it initiates the SRB SEPARATION SEQUENCE that kicks the solids off the vehicle. In case both chamber pressures don't come down (as they might not if sensors had failed), the software blows the solids loose anyway at 129.8 seconds mission elapsed time since the solids cannot physically burn that long.
(During the first few flights, the crew made a "Pc < 50" call to the ground.)
Philip Sloss
Post by: RedSky on 12/19/2005 04:15 pm
Basically saying that as of SRB sep, the expected velocity is what is should be. I remember on one flight, however, hearing a "First stage performance: Low" call. Apparently the SRB performance wasn't as good as expected. Then hearing something like "expect future calls to be late". Thus, becuse it wasn't quite as fast as is should have been going, the main engines would be firing longer, and the expected timings for the abort calls would not occur on time since they are also a function of velocity as well as altitude and location.
Post by: Flightstar on 12/19/2005 04:51 pm
Post by: RedSky on 12/19/2005 05:34 pm
Quote
Flightstar - 19/12/2005 11:51 AM
Can you remember which launch that was? My mind isn't what it used to be in my old age. The SSMEs can only fire for as long as the ET allows prior to a MECO deterimed by the ECO sensors. APU assist helps. If it was too low a performance then an abort would be called.
Sorry, can't recall. It was probably fairly early... before the Challenger accident. I just recall hearing it and thinking... Oh? Then the (CNN) former astronaut / commentator just mentioned casually that it must have been a slight underperformance in the SRBs., but wasn't anything that the main engines couldn't make up the difference (obviously, or there would have been some form of notice of a possible abort call). It wasn't the "Abort ATO" of 51F.
Post by: psloss on 12/19/2005 05:38 pm
Post by: psloss on 12/19/2005 07:35 pm
In the handful of launches I quickly reviewed (most of which were after 1995), all I heard was "performance nominal," though it was a small sampling.
Philip Sloss
Post by: Stardust9906 on 12/19/2005 08:44 pm
Quote
Flightstar - 19/12/2005 5:51 PM
Can you remember which launch that was? My mind isn't what it used to be in my old age. The SSMEs can only fire for as long as the ET allows prior to a MECO deterimed by the ECO sensors. APU assist helps. If it was too low a performance then an abort would be called.
I happen to have a video of this one. It was STS-41C
Post by: Flightstar on 12/19/2005 09:34 pm
Post by: psloss on 12/19/2005 10:23 pm
Quote
Flightstar - 19/12/2005 5:34 PMWell, I'll take "APU assist" for the mains over hydraulic lockup any day. :)
Thanks I'll look for history. I'd also like to say I've no idea why I wrote APU assist!!!!! Explains why I'm on part-time work as I near retirement!
Actually did a little more digging and found this relatively loquacious exchange on STS-5:
Capcom (Bob Stewart): "Columbia, this is Houston, your first stage was low on performance this morning."
CDR (Vance Brand): "OK, fine."
Philip Sloss
Post by: Shuttle Man on 12/19/2005 10:55 pm
Thanks for bringing back a warm memory.
Post by: psloss on 12/19/2005 11:34 pm
http://www.geocities.com/spaceshot2000/sss-faq.htm
Also, this is a good "inside the MCC" article by Mr. Grabois:
http://www.geocities.com/spaceshot2000/mcc.htm
(Apologies again if I'm duplicating other posts here.)
Philip Sloss
Post by: NASA_Twix_JSC on 12/19/2005 11:54 pm
Post by: psloss on 12/19/2005 11:58 pm
http://space.balettie.com/
Post by: Chris Bergin on 12/20/2005 12:09 am
This is also worth a mention: http://space.balettie.com/LastDay.html
Says it all really.
Post by: psloss on 12/20/2005 12:25 am
Quote
Chris Bergin - 19/12/2005 8:09 PMI don't know; I stopped lurking in s.s.s. for a long time after 1 February 2003. (It was bad enough the loonies in there before we lost Columbia; I thought the newsgroup was almost worthless for a while after that, with few exceptions.)
Did he stop because of Columbia? I ask as I've been meaning to mail him for a long long time, but wouldn't want to intrude if this is the case?
This is also worth a mention: http://space.balettie.com/LastDay.html
Says it all really.
It should be fairly easy to search for his posts, though...
Philip Sloss
Post by: Mark Max Q on 12/20/2005 01:26 am
Post by: James Lowe1 on 12/20/2005 02:30 am
Post by: psloss on 12/20/2005 12:48 pm
http://www.ktb.net/~billmeco/
(I would presume that Ben has run into Mr. Hartenstein at various pad camera setups and elsewhere at the Cape.)
Philip Sloss
Post by: Hotol on 12/20/2005 01:35 pm
Post by: FransonUK on 12/20/2005 02:10 pm
http://www.ktb.net/~billmeco/STS114RolloutW17.jpg
Post by: braddock on 12/20/2005 04:49 pm
I guess the recent SpaceX flights have made me aware of my ignorance of LOX handling, and thinking of that huge ET and the issues it must have has raised some questions.
How is LOX for the Space Shuttle generated and stored before launch? And shouldn't the ET be absolutely smoking with boiloff, or is it piped out through the ground facility arm and vented somewhere?
Am I right in my conclusion that for ground storage LOX can be held in heavy pressurized tanks that eliminate boiloff? It is only because of the light-weight requirements of the tanks in the ET (or other rocket) that the LOX needs to be at a lower pressrue, and boiloff occurs? Or do I misunderstand?
Also, is condensation on the ET ever a problem or launch weight consideration, or does the insulation largely take care of that?
Thanks.
Post by: Shuttle Man on 12/26/2005 11:14 pm
The ET is constantly topped up until just prior to launch, with pressurization. Insulation stops condensation (most of) on the ET.
Post by: Rocket Guy on 12/27/2005 02:47 am
Post by: Flightstar on 12/27/2005 05:40 pm
Post by: Terrible Twosome on 12/29/2005 11:41 pm
Like this:
........SSMEs.........
...........1m...........
3.3m<
It's imbalanced?
Post by: Rocket Guy on 12/30/2005 02:43 am
Post by: braddock on 12/30/2005 03:35 am
Post by: Flightstar on 12/30/2005 03:46 am
Quote
braddock - 29/12/2005 10:35 PM
How do they generate and store all that LOX? Are there LOX tanks out at each of the pads? Or is it piped in from some central facility?
At the pads at the LC-39 Launch complex.
LOX Tank 900,000 gallons at -300F, at North West corner.
LH2 Tank 850,000 gallons at - 420F at North East corner.
Post by: Flightstar on 12/30/2005 03:50 am
Post by: braddock on 12/30/2005 11:27 am
Quote
Flightstar - 29/12/2005 11:46 PM
LOX Tank 900,000 gallons at -300F, at North West corner.
LH2 Tank 850,000 gallons at - 420F at North East corner.
Wow, the scale of these things is just unbelievable. That must be one helluva refer out there.
Post by: Chris Bergin on 12/30/2005 01:20 pm
I remember the 'steam' you see on the lines from the tanks to the pad, when tanking the ET.
Post by: BenB5150 on 12/30/2005 03:35 pm
Ben
Post by: Flightstar on 12/30/2005 04:54 pm
Quote
BenB5150 - 30/12/2005 10:35 AM
I've been doing research for my shuttle models and knew that Columbia had a unique tile arrangement on her wings. Does anyone know why Columbia had this and why it never changed when she went in for any of her OMDP? Also was there a reason why the crew cabin area was never redone with thermal blankets?
Ben
The thermal issues were not fully understood until later, so she flew with the black tile configuration as their was expected to be higher than realized thermal heating on those black sections. Basically, we never got around to changing her to the configuation that you see on the other Orbiter TPS layout and she even kept her empty SILTS pod on the tail section. Changing TPS is a long process and even during an OMM period.
Post by: anik on 12/30/2005 06:41 pm
Post by: Flightstar on 12/30/2005 06:43 pm
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anik - 30/12/2005 1:41 PM
Flightstar is the Elite Veteran!... :) Congratulations!...
Must be my age! :)
Post by: Firestarter on 01/01/2006 07:34 pm
1) Landing Gear failure (so close to actual landing. Could the orbiter just belly slide? Not great for the orbiter, but at least the crew might be ok?)
2) Paracute failure (how much extra rollout would this cause?)
3) The two parts of the tail that spread out (same as above)?
Thanks.
Post by: Rocket Guy on 01/01/2006 08:24 pm
Post by: Firestarter on 01/01/2006 08:26 pm
Post by: BogoMIPS on 01/02/2006 03:15 am
For the most part, Shuttle is an automated system, with a few things done manually by the crew aboard (landing. Could the existing shuttles be modified to allow for unmanned operations? Presumably they could, but would it be worth it?
My first thought was to use the new CLV to orbit the modules, as it will likyle be availabe in the next couple years (before the new SDHLV), but the required payload adapters and mass involved meant that launcher wasn't capable of launching all of the modules.
My next thought is that you use unmanned shuttle launches to get the remaining modules to ISS. Once docked (and that might be the real trick), the ISS crew could board the orbiter, if not everything about the process could be automated.
Then the orbiter could un-dock, and head home.
If one or more of the remaining orbiters could be flown unmanned, it might allow for ISS completion without addressing all of the concerns for crew risk.
Post by: psloss on 01/02/2006 06:43 am
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Firestarter - 1/1/2006 4:26 PMFor reference, they did a "minimal braking" test on STS-44; it's not necessarily a perfect analog for a concrete runway, but that Edwards lakebed landing rollout took up over 11000 feet:
Thanks. That explains the really long runways as a safety margin, rather than the orbiter needing all the length.
http://www-pao.ksc.nasa.gov/kscpao/shuttle/missions/sts-44/mission-sts-44.html
Post by: Jonesy STS on 01/02/2006 01:49 pm
Post by: Chris Bergin on 01/02/2006 05:38 pm
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Jonesy STS - 2/1/2006 2:49 PM
What protection is there on the windows for the flight deck when launching? All that pressure, surprised glass windows are a good idea?
Welcome to the site :)
The windows on the Orbiter are very strong and very thick, made up on several layers.
There was some concern on STS-114 about MMOD (Micrometeoroid and Orbital Debris) hits on a few windows, but hasn't been mentioned again - so doesn't appear to be a concern....but you get the idea, these windows are very strong and thick.
Post by: anik on 01/02/2006 08:40 pm
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
Post by: Chris Bergin on 01/02/2006 09:00 pm
Post by: truebeliever on 01/02/2006 09:36 pm
I have often thought about a possible interim option to help with the current foam problems.... Have the astronauts fly up on Soyuz, fly the shuttle unmanned with cargo. Upon docking inspect for any damage to the tiles. If none, board it and fly it back. If some are damaged, repair if possible. The Soyuz would still be availabe for safe return in a worst case scenario.
I think we are going to have to do some real test flights to get all of the foam issues behind us. This would minimize the risk.
The only question is can the orbiter dock automatically with the ISS?
Post by: Shuttle Man on 01/02/2006 09:41 pm
Docking with the ISS would simply incorpate the level of currently available Progress automation.
So yes.
Chris did a story on automation of the fleet being possible?
Post by: Chris Bergin on 01/02/2006 09:43 pm
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Shuttle Man - 2/1/2006 10:41 PM
Chris did a story on automation of the fleet being possible?
Wasn't me, but one of our initial writer pool journalists, Kathryn:
http://www.nasaspaceflight.com/content/?id=26
Post by: BogoMIPS on 01/03/2006 01:41 am
I hadn't thought of the angle posed in the article of off-loading the crew at ISS and attempting to remote-land a potentially damaged orbiter, but that is another excellent reason that such a system should be implemented.
Computer-piloted vehicles landing themselves occured more than once on several X-plane models, so I have no doubt this could be done. The real questions are:
1. How much $?
2. How long to implement?
The article was written back in April of '05. I wonder if the idea was seriously revisited after STS-114's foam shedding incident.
Post by: Bruce H on 01/03/2006 04:42 am
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BogoMIPS - 2/1/2006 8:41 PM
Thanks for that link Chris... *Very* interesting to know it was at least considered!
I hadn't thought of the angle posed in the article of off-loading the crew at ISS and attempting to remote-land a potentially damaged orbiter, but that is another excellent reason that such a system should be implemented.
Computer-piloted vehicles landing themselves occured more than once on several X-plane models, so I have no doubt this could be done. The real questions are:
1. How much $?
2. How long to implement?
The article was written back in April of '05. I wonder if the idea was seriously revisited after STS-114's foam shedding incident.
1) Not much, about $5 per orbiter, max.
2) Ironically, over the space of the downtime while the PAL ramp issue is being dealt with, but it seems they've stretched their resources to thinly to take this option seriously.
Post by: BogoMIPS on 01/03/2006 02:04 pm
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1) Not much, about $5 per orbiter, max.
Well, I don't think anything on the Shuttles costs only $5. :) The obviously known systems that aren't automated (landing gear, atmospheric instrument probes) seem like pretty simple systems to automate:
Atmospheric Probes: at altitude X, deploy.
Landing gear: Deploy during final approach at appropriate time (not going to look it up in more detail at the moment).
Linking these automations into the computer system(s) on the orbiter, and testing them enough to trust them will likely some time. You don't anything like this deploying during re-entry, for obvious reasons.
Heck, you don't even need to really "automate" the gear deployment... Just enable radio-control of it! Something similar to the range safety destruct systems... Signal coded ARM and DEPLOY messages from a ground station to the orbiter during final approach, and for the atmospheric probes during descent.
If there's a crew aboard, simply don't use that remote equipment!
I agree that implementing this seems, from my aerospace engineering armchair here, to be a no-brainer...
Post by: Bruce H on 01/03/2006 02:11 pm
Post by: dmc6960 on 01/03/2006 05:53 pm
-Jim
Post by: UK Shuttle Clan on 01/03/2006 06:34 pm
So the SSME is quiet envioromentally sound, given the by product is water vapour and some hydrogen?
Post by: UK Shuttle Clan on 01/03/2006 06:39 pm
Post by: rsp1202 on 01/03/2006 07:27 pm
Post by: rsp1202 on 01/03/2006 07:57 pm
http://www.ilslaunch.com/pictures/atlas_v/original/AV001-Launch.jpg
and:
Post by: rsp1202 on 01/03/2006 07:58 pm
Post by: Rocket Guy on 01/03/2006 08:28 pm
Take a look at side-angle Shuttle photos and you can see the long flame from the main engines; top one here:
http://www.launchphotography.com/STS114launch.html
Post by: FransonUK on 01/03/2006 08:35 pm
Don't let me near a camera, I always take shots with people's eyes apparently becoming red! :o ;)
So what's coming out of the SRBs? Apparently it's a secret mix? I know it's been described as like rubber eraser filings in a cement mix type formula when poured into the segments?
Post by: nacnud on 01/03/2006 11:48 pm
Is there a good overview of how the orbiter copes with thermal issues anywhere?
Post by: Rocket Guy on 01/04/2006 03:18 am
Post by: Jonesy STS on 01/05/2006 09:34 am
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Ben - 3/1/2006 10:18 PM
Nah, its on spaceflight.nasa.gov in the Shuttle reference section. It's basically Aluminum powder as the fuel, ammonia perchlorate as the oxidizer, and a polymer glue holding it together.
Just what every growing boy needs....
Why is it that when the SRBs light up, they don't shoot off and rip themselves free of the rest of the stack?
Only two points where they are linked with the ET, are they made of someone amazingly strong?
Post by: SimonShuttle on 01/05/2006 10:11 am
Post by: Jonesy STS on 01/05/2006 01:24 pm
Post by: Mark Max Q on 01/08/2006 06:30 pm
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Jonesy STS - 5/1/2006 8:24 AM
Ok, still an imbalance of about 5.5 million lbs of thrust pounding up the side of you, taking the million pounds you've got from the SSMEs. Really can't work out why the SRB attach points don't rip out of the side of the ET or SRB when the SRBs are fired.
Good question.
Post by: psloss on 01/08/2006 06:43 pm
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Mark Max Q - 8/1/2006 2:30 PMGoogle is your friend -- at least for now. Here's a good answer (I think):QuoteJonesy STS - 5/1/2006 8:24 AM
Ok, still an imbalance of about 5.5 million lbs of thrust pounding up the side of you, taking the million pounds you've got from the SSMEs. Really can't work out why the SRB attach points don't rip out of the side of the ET or SRB when the SRBs are fired.
Good question.
http://groups.google.com/group/sci.space.shuttle/msg/fdcd9837c09b784d?hl=en&
Post by: Orbiter Obvious on 01/09/2006 12:47 am
Post by: Super George on 01/09/2006 03:05 am
Post by: Hotol on 01/09/2006 06:48 am
Post by: Rocket Guy on 01/09/2006 05:14 pm
Post by: Jamie Young on 01/11/2006 12:08 am
Post by: possum on 01/12/2006 12:23 am
The two "mini-towers" on the MLP are called Tail Service Masts (TSM) and they are the LOX and LH2 umbilicals that fuel the vehicle prior to lift-off. The LOX and LH2 go into the Orbiter aft propulsion piping and into the ET and is drained back through the same piping to the engines during launch. The TSM's are attached while in the VAB and they are designed to remain attached to the Oribiter with significant movement, not just during rollout but also during main engine buildup prior to SRB ignition. The TSM's must remain attached until the SSME's are at full thrust and the SRB's iginite (they actually separate "in flight") because if the SSME's shut down before reaching full thrust, you have to be able to drain the ET and safe the vehicle.
Post by: Jamie Young on 01/12/2006 12:42 am
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rmathews3 - 11/1/2006 7:23 PM
The two "mini-towers" on the MLP are called Tail Service Masts (TSM) and they are the LOX and LH2 umbilicals that fuel the vehicle prior to lift-off. The LOX and LH2 go into the Orbiter aft propulsion piping and into the ET and is drained back through the same piping to the engines during launch. The TSM's are attached while in the VAB and they are designed to remain attached to the Oribiter with significant movement, not just during rollout but also during main engine buildup prior to SRB ignition. The TSM's must remain attached until the SSME's are at full thrust and the SRB's iginite (they actually separate "in flight") because if the SSME's shut down before reaching full thrust, you have to be able to drain the ET and safe the vehicle.
Thanks, that explains why they are on the MLP, so they can keep the Shuttle steady from the point of mating to launch. Seems obvious now, but sometimes you need someone to tell you! :)
Post by: Orbiter Obvious on 01/12/2006 01:54 am
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rmathews3 - 11/1/2006 7:23 PM
The two "mini-towers" on the MLP are called Tail Service Masts (TSM)
Great, I'll add that to Chris' list for new people.
STS = Space Transportation System
ET = External Tank
OV = Orbiter Vehicle (such as OV-103 is Discovery, 04 is Atlantis, O5 is Endeavour)
SRB = Solid Rocket Booster
OMS = Orbital Maneuvering System
RCS = Reaction Control System
MPL = Mobile Launch Platform (Rides on the Crawler Transporter, Shuttle Stack goes on top of the MLP).
VAB = Vehicle Assembly Building
MECO = Main Engine Cut Off
SSME = Space Shuttle Main Engine
MAF = Michoud Assembly Facility
MSFC = Marshall Space Flight Center
KSC = Kennedy Space Center
RLV = Reusable Launch Vehicle
LOX = Liquid Oxygen
LH2 = Liquid Hyrogen
ECO = Engine Cut Out (sensor)
TSM = Tail Service Masts
Post by: possum on 01/12/2006 11:27 am
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Jamie Young - 11/1/2006 7:42 PM
Thanks, that explains why they are on the MLP, so they can keep the Shuttle steady from the point of mating to launch. Seems obvious now, but sometimes you need someone to tell you! :)
The TSM's don't really keep the Shuttle steady, if fact, you don't want them to impart any loads into the Shuttle structure. The Shuttle stack is supported entirely from the base of the SRB's, with the Shuttle cantilevered off the side of the ET. The TSM attachment "floats" with the Shuttle as is sways back and forth. In fact, when the SSME's are building thrust prior to SRB ignition, the Shuttle stack is flexed forward and when it rocks back to vertical, the SRB's are fired. The TSM's must stay attached to the Shuttle during this "twang" of rocking back and forth. If you look at the video of the STS-105 launch on page 5 of the FTP video collection, you can see the aft end of the Shuttle lift up more than a foot when the engines ignite, this translates into 30 inches of movement at the tip of the ET. If you look real close, you can see the TSM umbilical plate attached to the Shuttle right next to the OMS pod and when the stack rocks back and the SRB's ignite, the umbilical plate disappears into the TSM in the blink of an eye.
By the way, those "sparklers" you see during SSME ignition are called Radially Outward Firing Initiators (ROFI's) and they are there to ignite any unburned hydrogen coming out of the SSME's during startup, otherwise hydrogen gas could build up in pockets of dead air in the aft area and explode.
The TSM's are attached to the Shuttle to provide services, the main service being LOX and LH2 fill and drain. There are also many electrical and fluid services going through the umbilical plate. The mating plate is about 3 feet wide by 4 feet tall and it has numerous quick disconnects (QD's) for fluids and electrical services. Many things go through this interface including all of the software commanding up until T-31 seconds when control of the countdown is handed off to the Shuttle. If the launch team wants to stop the countdown, the commands go through this interface. That is another reason why these umbilicals are attached until the SRB's are ignited and there's no stopping the launch. All the critical interfaces between the ground and the flight vehicle go through the TSM's. And since there are 2 TSM's, there are redundant services going through each TSM so that if one inadvertently disconnects prematurely, you still have the critical commanding capability through the other one.
Post by: psloss on 01/12/2006 11:53 am
I believe the hydrogen burn igniters start at T-10 seconds and stop at T-0 (don't know if that's at depletion or not); what's interesting about that is the last cutoff on the pad (STS-68) was initiated so close to T-0 (at -1.9 sec.), that the igniters stopped before the shutdown sequence was completed.
There have also been a few cases where a hold was called after the igniters started but before the engine start commands were sent (STS-93 being one example; another would be the first STS-26 FRF attempt).
Post by: Rocket Ronnie on 01/12/2006 12:03 pm
Post by: psloss on 01/12/2006 12:24 pm
Quote
Rocket Ronnie - 12/1/2006 8:03 AMHopefully Mr. Mathews or one of the other NASA or contractor folks here can answer that; from past experiences, I believe that the cutoff logic/philosophy changes from before liftoff to after liftoff. I would presume that the launch can be aborted anytime up to the commands that start the SRBs and fire the pyros for the hold downs.
Cool, another NASA person on here! What's the last point in which a countdown can be cutoff? I've seen at least one where the SSMEs are on the way to 100 (or 104) percent and an abort has been called, engines shut down, stack is rolling about because of the SSMEs and the safing even had jets of water spraying on the aft of the orbiter. That was about T-3seconds I think.
In the case of the STS-68 cutoff, it was reported that the right engine started a little slowly such that the high pressure oxidizer turbine (HPOT) discharge temperature was slightly over the limit; however, at the time of the cutoff, I believe it was also reported that the limit changes with time and would have increased slightly such that the discharge temp would have been within the limit just a few hundred milliseconds later. (At the time, I believe it was reported that the sensor sample rate was every 20 or 40 milliseconds.)
Regarding the "boattail" water deluge, I believe the system has been in place since the first launch; however, I don't believe it was used in any of the planned or unplanned cutoffs until the 26 June 1984 launch attempt for STS-41D, where the nature of the shutdown left enough hydrogen gas in the area to help ignite some RTV on the orbiter (I believe) and start a fire. Since that event, I believe the deluge activates automatically in case of a cutoff.
Post by: JamesSpaceFlight on 01/12/2006 12:24 pm
Post by: Space101 on 01/12/2006 12:31 pm
Long thread on this here http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=989&start=1 - the article by this site was first, then Florida Today and CBS News and Associated "we hate NASA" Press followed three days later. So we're all hoping this place gets to follow it up as no one else is.
Post by: Chris Bergin on 01/12/2006 01:25 pm
I do need to find myself an Orbiter tech who works with SSMEs though.
Post by: Launch Fan on 01/12/2006 05:44 pm
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?
Post by: possum on 01/12/2006 06:19 pm
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=989&start=131&posts=135
Post by: Avron on 01/12/2006 07:20 pm
Quote
rmathews3 - 12/1/2006 2:19 PM
SSME shutdown can happen up to the last millisecond as far as I know. There was one mission where the countdown clock at the press site read 0:00:00 after an engine shutdown and everyone was freaking out thinking the bolts may have released and the Shuttle was teetering on the pad. Of course, that would never happen. As for the O2 leak in the aft, I posted on this thread what I know:
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=989&start=131&posts=135
I understand the bolts go first then SRB ignition, So I guess as long as the Piros have not been triggered shutdown is an option.. Was wondering if the hold down bolt trigger where EH.. hardwired to SRB's or was under control directly and independantly from the onboard sequencer
Post by: mkirk on 01/12/2006 08:11 pm
I understand the bolts go first then SRB ignition, So I guess as long as the Piros have not been triggered shutdown is an option.. Was wondering if the hold down bolt trigger where EH.. hardwired to SRB's or was under control directly and independantly from the onboard sequencer
Edited by Avron 12/1/2006 2:21 PM
Hey All-
I am a new user so pardon me if I am not posting correctly,
I dont' understand the second part of your question but regarding the first half: The command to fire the SRB hold down posts and the SRB ignition command are actually sent to both redundant circuits as a fire 1 command, fire 2 command for each system...in that order (seperation then ignition) essentially simultaneously...I don't recall the exact milliseconds. Each system, holdown and ignition has two redundant circuits. The commands are sent via the onboard master events controller (MECs). All events after auto sequence start (T-31 seconds) are conducted by the onbaord general purpose computers (GPCs). Once the command is sent there is no stopping anything...it can not be revoked. You are either going to have a good clean liftoff with two SRBs thrusting or you are going to have a bad day.
Post by: Chris Bergin on 01/12/2006 08:31 pm
Post by: psloss on 01/12/2006 11:09 pm
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rmathews3 - 12/1/2006 2:19 PMYeah, that was STS-68; the MSFC report is still cached on Google, but I can't get to the original link.
...There was one mission where the countdown clock at the press site read 0:00:00 after an engine shutdown and everyone was freaking out thinking the bolts may have released and the Shuttle was teetering on the pad...
This is a link to the Google cache copy. (http://64.233.167.104/search?q=cache:WeDOhrngyS8J:spacelink.nasa.gov/NASA.Projects/Human.Exploration.and.Development.of.Space/Human.Space.Flight/Shuttle/Shuttle.Missions/Flight.065.STS-68/Launch.Information/Launch.Abort+STS-68+Launch+Abort&hl=en)
Excerpts:
Quote
STS-68 LAUNCH ATTEMPT REPORT
AUGUST 18, 1994
GEORGE C. MARSHALL SPACE FLIGHT CENTER
Cynthia A. Snoddy
Chairman, MSFC Space Shuttle
Flight Evaluation Team
.
.
.
ON-PAD ABORT DATE: August 18, 1994
LAUNCH WINDOW: 5:54 am - 9:24 am CDT
ON-PAD ABORT TIME: 94:230:10:53:58.157 GMT
5:54 am CDT
NSTS DATABASE T-REF: 94:230:10:54:00.000
SSME#3 START TIME: 94:230:10:53:53.437
SSME#2 START TIME: 94:230:10:53:53.558
SSME#1 START TIME: 94:230:10:53:53.679
SSME#3 SHUTDOWN TIME: 94:230:10:53:58.157
SSME#2 SHUTDOWN TIME: 94:230:10:53:59.358
SSME#1 SHUTDOWN TIME: 94:230:10:54:00.638
.
.
.
1.0 STS-68 LAUNCH ATTEMPT SUMMARY
The scheduled launch of STS-68 on August 18, 1994 was aborted on Launch Pad 39A
(MLP-1) at the Kennedy Space Center (KSC) shortly after the main engine start
command was issued. The on-pad abort occurred at approximately 5:54 A.M.
Central Daylight Time (CDT) (094:230:10:53:58.157 GMT). The abort was executed
because of a ME-3 Failure Identification (FID) due to the High Pressure
Oxidizer Turbopump discharge temperature exceeding a redline. The
investigation of the abort is discussed in section 2.3.
.
.
.
2.3 SPACE SHUTTLE MAIN ENGINE - SSMEs 2012, 2034, 2032
All SSME parameters appeared to be normal throughout the prelaunch countdown
and were typical of prelaunch parameters observed on previous flights. Engine
"Ready" was achieved at the proper time and all LCC were met.
2.3 SPACE SHUTTLE MAIN ENGINE - SSMEs 2012, 2034, 2032 (cont)
The on-pad launch abort occurred because the ME-3 (E2032) High Pressure
Oxidizer Turbine (HPOT) discharge temperature Channel A exceeded a pre-liftoff
redline check resulting in a Failure Identification (FID) and subsequent engine
shutdown. At Engine Start Command (ESC) plus 2.3 seconds through ESC plus 5.8
seconds the HPOT discharge temperature must not exceed 1560 R. The ME-3 HPOT
discharge temperature Channel A was 1576 R. The Channel B measurement was 1530
R which was also higher than predicted. Instrumentation/data appears to be
valid.
ME-3 was commanded to shutdown at ESC plus 4.72 seconds. ME-2 and ME-1
subsequently shutdown at ESC plus 5.80 seconds and 6.96 seconds respectively.
The shutdowns were all nominal and placed the vehicle in a safe status.
The cause of the high turbine discharge temperature is under investigation and
a number of factors could in combination have led to the overshoot temperature
response (e.g. fuel side build-up characteristics, sequencing changes prior to
STS-68, turbopump efficiencies, hardware degradation, etc.). The current plan
of action is to establish investigation teams, perform fault tree analysis,
engine inspections and detailed data and film evaluation.
Note that the last shutdown command occurred after what would have been T-0! That was definitely a heart-stopper for me, even just watching it live on TV.
Philip Sloss
Post by: Jamie Young on 01/12/2006 11:52 pm
Post by: Mark Max Q on 01/13/2006 02:03 am
Quote
Jamie Young - 12/1/2006 6:52 PM
Wow, anyone got a link to a video of that?
Yes, but be warned, it's a very very very slow download, almost dialup speed. You might be spoiled by the speed of the dedicated FTP server here.
Still, this is it and it's worth it.
http://www.insideksc.cjb.net:8081/wwwroot_45/DIVX/STS-68/sts_68_divx.htm
Post by: Firestarter on 01/13/2006 03:25 am
Post by: Avron on 01/13/2006 03:36 am
Quote
mkirk - 12/1/2006 4:11 PM
re:
I understand the bolts go first then SRB ignition, So I guess as long as the Piros have not been triggered shutdown is an option.. Was wondering if the hold down bolt trigger where EH.. hardwired to SRB's or was under control directly and independantly from the onboard sequencer
Edited by Avron 12/1/2006 2:21 PM
Hey All-
I am a new user so pardon me if I am not posting correctly,
I dont' understand the second part of your question but regarding the first half: The command to fire the SRB hold down posts and the SRB ignition command are actually sent to both redundant circuits as a fire 1 command, fire 2 command for each system...in that order (seperation then ignition) essentially simultaneously...I don't recall the exact milliseconds. Each system, holdown and ignition has two redundant circuits. The commands are sent via the onboard master events controller (MECs). All events after auto sequence start (T-31 seconds) are conducted by the onbaord general purpose computers (GPCs). Once the command is sent there is no stopping anything...it can not be revoked. You are either going to have a good clean liftoff with two SRBs thrusting or you are going to have a bad day.
mkirk welcome,
You answered my second part, so we have two circuits independently commanded from the MEC, one for hold down and one for SRB ignition. What is the chance that MEC fails between the two?
Post by: Tahii on 01/13/2006 06:44 am
Quote
Mark Max Q - 13/1/2006 2:03 PMCheers. Took me 5 mins to download :D
Yes, but be warned, it's a very very very slow download, almost dialup speed. You might be spoiled by the speed of the dedicated FTP server here.
Still, this is it and it's worth it.
http://www.insideksc.cjb.net:8081/wwwroot_45/DIVX/STS-68/sts_68_divx.htm
Post by: Chris Bergin on 01/13/2006 09:56 am
On the video "3, 2, 1 AND....we have a cut off" yikes. Also interesting to see the close up of SSME shutdown, with the center and right engine taking a good second to power down after the left closed off. Both left and right gimbal to launch position and then gimbal back out, was new to see also.
Post by: psloss on 01/13/2006 11:47 am
Quote
Chris Bergin - 13/1/2006 5:56 AMThe way the live TV cut between cameras and the timing of the cutoff made it a little extra dramatic; the engines are gimballed to launch position after they all reach mainstage and they cut to the wide shot just as they were finishing that -- and also just as the cutoff started with the engines being moved back to start position and the shutdown command going to the center engine.
Might of taken some people longer as he minute someone linked it up, you'll of seen a number go download it at the same time.
On the video "3, 2, 1 AND....we have a cut off" yikes. Also interesting to see the close up of SSME shutdown, with the center and right engine taking a good second to power down after the left closed off. Both left and right gimbal to launch position and then gimbal back out, was new to see also.
The video also shows what I mentioned earlier in the thread -- the hydrogen burn igniters stop at T-0, even though the shutdown sequencing is still in progress. That probably contributed to a little extra free, unburned hydrogen before the water deluge started. (Another thing interesting thing to me with the water deluge is seeing how hot the boattail got with the engines running at mainstage -- when the water comes on, look at the steam coming off the tail, etc.)
I believe this event contributed to the choice of a picture in picture for the live liftoff broadcast in many of the subsequent launches.
Post by: Jonesy STS on 01/13/2006 12:22 pm
Post by: possum on 01/13/2006 12:35 pm
1)Three signals must be present simultaneously for the PIC to generate the pyro firing output. These signals (arm, fire 1 and fire 2) originate in the orbiter general- purpose computers and are transmitted to the MECs.
2)The solid rocket motor ignition commands are issued by the orbiter's computers through the master events controllers to the hold- down pyrotechnic initiator controllers on the mobile launcher platform. They provide the ignition to the hold- down NSDs.
Let me interpret to clarify that the signal to ignite the SRB's and to release the holddown bolts are one and the same. The signal is actually three signals - arm, fire1 and fire2, all must be present to initiate the pyros. The command comes from the Orbiter computer and goes to the Master Events Controller (MEC). The MEC sends the signal to both the SRB igniter and the holddown post pyros (and other T-0 events). There is probably a few milliseconds difference in the two firing events due to response time and legth of wiring, but it is a single command to initiate both. All signal paths are redundant, there are two for each SRB igniter and two for each of the 16 charges on the holddown bolts (2 each for all 8 bolts). I believe that the MEC sends this same signal for SRB ignition to the 8 holddown bolts, both TSM umbilicals, and the Hydrogen Vent Arm. These are all T-0 events and are all initiated by the same command from the on-board computers and distributed by the MEC to all destinations through redundant electrical paths.
Post by: Chris Bergin on 01/13/2006 12:38 pm
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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.
Post by: possum on 01/13/2006 01:27 pm
Post by: mkirk on 01/13/2006 04:24 pm
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.
Post by: possum on 01/13/2006 05:27 pm
Post by: possum on 01/13/2006 05:56 pm
Post by: Mark Max Q on 01/13/2006 07:39 pm
Post by: Mark Max Q on 01/13/2006 07:41 pm
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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.
Post by: braddock on 01/13/2006 11:29 pm
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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:
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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:
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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.
Post by: anik on 01/14/2006 11:44 am
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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
Post by: FransonUK on 01/14/2006 12:49 pm
Post by: James Lowe1 on 01/14/2006 01:38 pm
Post by: Chris Bergin on 01/15/2006 07:00 pm
Post by: mkirk on 01/17/2006 02:24 am
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
Post by: Sergi Manstov on 01/17/2006 10:40 am
Was the heavyness of the US orbiter a big problem for landing?
Post by: possum on 01/17/2006 02:53 pm
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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).
Post by: Launch Fan on 01/17/2006 04:03 pm
Post by: psloss on 01/19/2006 12:33 am
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
Post by: mkirk on 01/19/2006 12:33 am
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
Post by: Avron on 01/19/2006 05:07 am
Question, what is this tank umbilical for?
Post by: DaveS on 01/19/2006 07:34 am
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Avron - 19/1/2006 7:07 AMThat 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 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?
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.
Post by: possum on 01/19/2006 11:23 am
Post by: Jonesy STS on 01/19/2006 11:37 am
Post by: possum on 01/19/2006 12:15 pm
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Jonesy STS - 19/1/2006 6:37 AM
Given the RSS is where it is in that picture, what purpose does the "path" that extends out of the back of the pad serve?
The path, which spits into a Y shape, is the rails for the old Saturn V flame deflector. The Saturn V flame deflector was capable of being moved in and out of the flame trench on rails. The Shuttle flame deflector is fixed in place, but the old rails remain. The Shuttle deflector is fixed in place because it is tied into the water deluge system.
Post by: Hotol on 01/19/2006 12:17 pm
There's another strange junction halfway up the crawlerway, before the turn to the other pad, but that's the old park up for the Saturn V Service Structure (Saturn V would rollout and then the Service Structure would rollout of the parking spot to ajoin to the Saturn V on the pad).
What you point out is different all the same.
Post by: Hotol on 01/19/2006 12:18 pm
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rmathews3 - 19/1/2006 7:15 AMQuoteJonesy STS - 19/1/2006 6:37 AM
Given the RSS is where it is in that picture, what purpose does the "path" that extends out of the back of the pad serve?
The path, which spits into a Y shape, is the rails for the old Saturn V flame deflector. The Saturn V flame deflector was capable of being moved in and out of the flame trench on rails. The Shuttle flame deflector is fixed in place, but the old rails remain. The Shuttle deflector is fixed in place because it is tied into the water deluge system.
Oh, there you go. I had no idea about that!
Post by: mkirk on 01/19/2006 01:03 pm
Post by: Justin Space on 01/19/2006 01:09 pm
Post by: possum on 01/19/2006 01:24 pm
Post by: Chris Bergin on 01/19/2006 01:34 pm
Already using one myself.
Post by: mkirk on 01/20/2006 01:23 am
The short answer is sometimes!!! When it comes to contingecy aborts there is no simple answer. There are just too many variables invovled such as how many engines have failed, when did they fail, are there other systems problems or flight control issues. If a an engine or APU comes apart in the back end of the orbiter it is likely that many other systems will be involved.
Shuttle Ascent trajectories are designed in such a way that from liftoff to MECO (main engine cutoff) if one engine fails there is always at least one CERTIFIED abort option. Those are AOA, ATO, TAL, and RTLS...pretty much in that order of preference for a performance problem (i.e. loss of thrust). The priorities can be different for systems problems such as loss of APUs, electrical bus failures, themal window pane breached etc.... In many cases the shuttle can loose two engines and still use one of these abort options. However there are significant portions of the trajectory where the loss of 2 or more engines will result in a contingecy abort, particularly in the early parts of the Ascent. Among these are so called black zones meaning they are not expected to be survivable.
The stated purpose of a contingency abort is to guide the orbiter to a safe gliding flight condition where a bailout or landing can be performed.
Abort boundaries are based on inertial velocity in feet per second. These boundaries are slightly different for every launch do to changes in variables such as vehicle weight, inclination, etc..
Getting back to the question of ECALs (east coast abort landings) which is a form of contingency abort: Using rough numbers from the STS-114 mission I will give you an example.
If you launched in the center of the launch window and had a two engine failure at a velocity of lets say 5,300 feet per second you could attempt an ECAL to Wilmington. This failure is so early in the Ascent (just after SRB sep) that TAL is not an option, in fact you havent even made it to the first TAL boundary which is at a velocity of 5,800 fps, and would only get you to Morone in Spain under a single engine failure scenario. Since we have lost two engines we are in a contingency abort situation at this point and the only potential landing site is Wilmington (disregarding contingency RTLS scenarios). The problem is the failure happend so early that the odds of making the runway at Wilmington are not good (the checklist actually has a little note that says "bailout in this region is probable"):( But if things worked out just right you could theoretically make it all the way:) Now if these two engines failed a little later, lets say at a velocity between 6,800 and 7,300 you can now choose between Wilmington and Cherry Point. You are solidly in the Wilmington boundary now, in fact that unpleasant little warning in the checklist is now gone... Well its not completely gone, because if we are at the early part of this boundary (ex: 6,800 fps to 6,900 fps) then an attempt at Cherry Point is regarded as a probable bailout region. Between 6,900 and 8,100 you would be in the heart of the Cherry Point window and that nasty little warning is gone again. Yet even without that warning there is no gaurantee you will make the runway.
I have only listed a couple of the tiny little windows here and only two of the 13 or so ECAL runways and yet the scenario was still pretty complex. In reality you have to consider the condition of the launch vehicle, the amount of energy you have (in terms of velocity), whether or not you launched at the opening, middle, or end of the launch window... Add to that potentially bad weather at your selected landing site. Launch rules don't evalluate weather at the Contingency sites because the failure modes that would get you there are considered to be relatively remote (i.e. it would take multiple failures) and there are so many sites that if weather had to be good at all of them you would never be able to launch. Just think of how many times we couldn't launch becuase of the 3 TAL sites not one of them had good weather.
Mark
Post by: psloss on 01/20/2006 02:07 am
It's been a while since I've asked the question and it didn't occur to me to do another Internet search until after I asked; I found a couple of interesting papers/presentations online (including a cue card with some 2 and 3 EO velocity boundaries) and some more recent Usenet posts/threads (last time I asked was back around 2000).
I guess I'd be asking the same question in a different way, but I'll throw it out, anyway: I see "black zones" referenced a lot in these contingency abort scenarios -- is there any kind of rule of thumb for them? I would assume that multiple engines out any time during first stage would be one of them, but the rest seems about as variable/hypothetical as my first question.
Anyway, thanks again. What has interested me in this for a long time is occasionally seeing/hearing little snippets of how the crews and control teams practice ascent and entry sims (and how much they simulate them).
Philip Sloss
Post by: mkirk on 01/20/2006 09:50 pm
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psloss - 19/1/2006 9:07 PM
I guess I'd be asking the same question in a different way, but I'll throw it out, anyway: I see "black zones" referenced a lot in these contingency abort scenarios -- is there any kind of rule of thumb for them? I would assume that multiple engines out any time during first stage would be one of them, but the rest seems about as variable/hypothetical as my first question.
Philip Sloss
Black Zones are always a touchy subject in the Flight Operations community: Basically anytime the shuttle's thrust to weight ratio is lower than that required to achieve orbit or an intact abort (RTLS, TAL, ATO, etc.) you are in a contingency abort. Depending on the numerous variables involved this could mean an ECAL, a Bermuda landing (for low inlcination missions), or a downrange landing at a TAL or ELS (emergency landing site), or a bailout. In all of these cases there as situations that are outside the shuttle's flight control and structural envelopes. For instance early 2 or 3 engine out failures can occur when the orbiter is high in altitude but has a relatively low velocity. This results in a severe re-entry pull-out that will likely overstress the vehicle (rip the wings off)...this is bad... and since it is not survivable it is designated as a black zone. Other black zones result from trying to maneuver at the limits of the flight control system or when trying to get off of the external tank at a dynamic pressure, angle of attack, airspeed, or altitude that will cause a recontact with the tank or exceed the tank's thermal limits (causing a rupture). Unlike a TAL or RTLS where you use up the fuel in the tank before seperation a contingency is so time critical that you don't have time to burn off the fuel and must seperate immiediately...this poses the threat that the propellant could "slosh" around at SEP and cause the tank to run into the orbiter...again these are all bad things.
I hope this gives you an idea of some of the many variables invovled.
Mark
Post by: psloss on 01/20/2006 10:11 pm
Thanks for all the info, Mark; I only wish I could sit in on some of the ascent sims to listen to the training. (The one JSC tour I did back in 1999 got into a viewing room above the flight control room, but we didn't get to stay for long or hear what they were practicing.)
Philip Sloss
Post by: Orbiter Obvious on 01/22/2006 03:18 am
Post by: mkirk on 01/22/2006 05:44 pm
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psloss - 20/1/2006 5:11 PM
One more and then I'll stop about this: is ET sep trickier in an RTLS or in a contingency abort? Given what you said about getting off the tank before propellant depletion in a contingency, that sounds worse, but would RTLS have a higher dynamic pressure, etc.?
Thanks for all the info, Mark; I only wish I could sit in on some of the ascent sims to listen to the training. (The one JSC tour I did back in 1999 got into a viewing room above the flight control room, but we didn't get to stay for long or hear what they were practicing.)
Philip Sloss
I don't no how to quantify how much riskier and RTLS or Contingency abort ET SEP would be. I can say there are certainly a lot more variables involved that can get your attention. After a normal MECO the orbiter is in a relatively benign environment. You are about 60 nautical miles up, the tank is ALMOST empty, there is zero thrust, no aerodynamic affects to speak of, and roll, pitch, and yaw rates are as close to zero as possible. This makes ET SEP a realtively straight forward event that is well understood.
During an RTLS you have hopefully reduced the propellant level in the tank to less than 2% to minimize slosh effects. The vehicle is considerabley lower so aerodynamic issues are a factor. The objective is to pitch the vehicle to an angle of attack of -2 degrees and hold attitude for MECO and ET SEP. This is a pretty dynamic event but the hope is that this attitude will permit a clean SEP without the aft attachment points hanging up or aero loads pushing the tank into the orbiter.
During a contingency the same concerns are present that I mentioned in my previous posts with the biggest issues being when in the trajectory are you trying to get off the tank. During a 3 engine out contingency in first stage you would (assuming the stack didn't come apart already) weight until SRB thrust tail off but prior to SRB SEP to conduct an ET "FAST SEP" from the entire stack (ET and SRB together as a single element) that would obviously be a high risk situation.
Mark
Post by: mkirk on 01/22/2006 06:01 pm
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Orbiter Obvious - 21/1/2006 10:18 PM
I know this should be answered with a "no", I need to ask it all the same. Does the orbiter use her wing flaps, avirons?, during any part of the ascent? I always used to think they got involved during the roll, but I know it's the SRBs gimballing now. But do they use the wings at all? I notice they test them before the launch like they do with airliners.
You are correct, during first stage steering is provided by gimbaling the SRB nozzles. After SRB SEP the SSMEs provide the steering of the orbiter including the roll to heads up around 5 1/2 minutes into the flight.
The evelvons on the aft of the orbiter's wings (2 on each side...an outboard and an inboard) do not provide attitude control going uphill (during launch). They do however, provide a very important function during early ascent called "load relief". If you look closely at videos showing a close up of the aft end of the shuttle during the climb out you will notice the elevons are deflected differentially...example the outboards might be up and the indoards down. [This is usually visible in the side shot videos as the orbiter goes thru the maximum aerodynamic pressure region] How much this occurs will very from flight to flight. This is done to even out the structural loads on the wings as it climbs thru the lower part of the atmosphere and the MAX Q region.
A side note: you will also see in some of these videos that the body flap located under the engines is vibrating. It actually moves around several inches but this is not do to flight control commands but rather from structural loads and vibrations.
Mark Kirkman
Post by: Orbiter Obvious on 01/22/2006 07:17 pm
Post by: Chris Bergin on 01/22/2006 08:18 pm
Post by: psloss on 01/22/2006 09:29 pm
After reading your answers, I think I have a better approach to asking more questions about this! But I don't want to hog the thread.
Thanks again,
Philip Sloss
Post by: Rocket Nut on 01/22/2006 10:18 pm
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psloss - 22/1/2006 5:29 PM
After reading your answers, I think I have a better approach to asking more questions about this! But I don't want to hog the thread.
Please don't worry about hogging the thread. You are asking good questions and WE are getting good answers. When I worked at Goddard, I had access to some of the training and planning manuals. I never got the answers to many of your questions. Hell, I never even thought to ask some of the questions. The answers have been very interesting to me. I'm a former pilot and never tire of this kind of info.
Cheers,
Lary
Post by: psloss on 01/23/2006 11:53 am
Philip Sloss
Post by: Rocket Nut on 01/23/2006 12:21 pm
Quote
psloss - 23/1/2006 7:53 AM
Maybe it's just me, but I do also see this thread serving as a running FAQ thread.
Philip Sloss
I can certainly agree with that statement...so keep on Asking your Questions...Frequently... :)
Cheers,
Larry
Post by: Chris Bergin on 01/23/2006 02:29 pm
As the site matures I'm sure they'll be some level of expansion in the forum layout - and this sort of thread will remain intact for as long as this site remains live.
Post by: Polecat on 01/24/2006 05:33 am
What makes the SSMEs gimbal? Is it hydrolic? I wondered about this as I believe it would be a lot of force to move the bells when they are firing!
Post by: Chris Bergin on 01/24/2006 09:10 am
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Polecat - 24/1/2006 6:33 AM
Hello.
What makes the SSMEs gimbal? Is it hydrolic? I wondered about this as I believe it would be a lot of force to move the bells when they are firing!
On the NASA reference pages it explains this as:
http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/sts-mps.html
"Three orbiter hydraulic systems provide hydraulic pressure to position the SSME servoactuators for thrust vector control during the ascent phase of the mission in addition to performing other functions in the main propulsion system. The three orbiter auxiliary power units provide mechanical shaft power through a gear train to drive the hydraulic pumps that provide hydraulic pressure to their respective hydraulic systems.
The ascent thrust vector control units receive commands from the orbiter GPCs and send commands to the engine gimbal actuators. The units are electronics packages (four in all) mounted in the orbiter's aft fuselage avionics bays. Hydraulic isolation commands are directed to engine gimbal actuators that indicate faulty servovalve position. In conjunction with this, a servovalve isolation signal is transmitted to the computers.
The SSME hydraulic servoactuators are used to gimbal the main engine. There are two actuators per engine, one for pitch motion and one for yaw motion. They convert electrical commands received from the orbiter GPCs and position servovalves, which direct hydraulic pressure to a piston that converts the pressure into a mechanical force that is used to gimbal the SSMEs. The hydraulic pressure status of each servovalve is transmitted to the ATVC units."
And people wonder why there's a need for a Q and A thread when NASA.gov explains it ever so clearly ;)
Post by: mkirk on 01/24/2006 11:23 pm
For example if you want to see the Launch and Ascent Trajectory Displays (which are actually pretty primitive since they were designed in the 1970's) you will be able to find them in the back of the Guidance, Navigation, and Control (GNC) section.
Main Engine Gimbaling would be in the MPS...sorry but it doesn't explain it any better than what Chris quoted earlier.
http://www.shuttlepresskit.com/STS-105/scom.htm
I hope you find it useful!
Mark
Post by: jschaef5 on 01/25/2006 01:12 am
Now I remember seeing a picture with 2 shuttles on 2 seperate pads at once. Why can't they make it a 0 day rule: launch with another shuttle ready to go. That way they won't have to spend time getting the shuttle ready and all that stuff. It just seems safer incase say the shuttle runs into the ISS and takes a huge chunk out and they can only survive on what they have in the shuttle or something. Theres tons of scenarios where they could need rescue in before 60 days is up. I am just wondering why do they say 60 (or 90) and not just go with the safest choice and say 0. I'd guess that 60 would be if they can dock with ISS and foam hit the shuttle and they need a ride home but 60 days isn't much, why not just have it ready at liftoff.
Post by: Chris Bergin on 01/25/2006 02:22 pm
Post by: possum on 01/25/2006 04:25 pm
Quote
jschaef5 - 24/1/2006 8:12 PM
Now I remember seeing a picture with 2 shuttles on 2 seperate pads at once. Why can't they make it a 0 day rule: launch with another shuttle ready to go. That way they won't have to spend time getting the shuttle ready and all that stuff.
I'm not the expert in this area, but that's never stopped me before so here's my opinion. To have 2 Shuttles ready to go at the same time would be very difficult with only three Orbiters in the inventory. Typically, the Shuttles are all at different stages of preparation; when one is at the Pad being readied for launch, another is being stacked in the VAB, another is in the middle of processing in the OPF, and another has just returned and is beginning processing in the OPF. That was when we had four, and even then, one was usually in an extended maintenance period undergoing upgrades and refurbishment. The 3 remaining Shuttles have seen their last extended maintenance periods (called OMDP, or Orbiter Maintenance Down Period), so that is no longer an issue. However, in order to do what you are proposing we would have to have 2 Shuttles processed and stacked and at the Pad ready to go. That would require us to wait longer and spend more resources (which are getting more scarce each passing day) to get 2 vehicles ready to fly. I believe there are also changes in the configuration of the Orbiter, particularly in the payload bay, depending on the type of mission and payload being flown. So until we know the type and nature of the mission, we can only process the Shuttle up to a certain point. As it stands now, the mission after STS-121 will be prepared to fly the P3/P4 truss combo to ISS. So there is a limit to how far in the process we could go and still be able to reconfigure for a rescue mission, especially since we would not know what we would need for the rescue mission depending on the nature of the emergency. To modify the processing scenario radically in order to muster a rapid response to an emergency would put the rescue mission at a much higher risk. So the 60 days allows us to prepare up to a point of divergence without deviating from our accepted methods and still be able to change the nature of the mission for a rescue using accepted practices and get the next launch off as soon as is deemed safe. If a rescue is not required, the processing would continue as needed to conduct the next mission in the ISS assembly sequence. Hope this helps.
Post by: Shuttle Scapegoat on 01/27/2006 01:26 am
Post by: mkirk on 01/27/2006 02:24 am
Quote
Shuttle Scapegoat - 26/1/2006 8:26 PM
The OMSS boom has sensistive imagary devices, Satellites have very sensistive parts, and I'm sure there are other areas, but I've never known how sensistive equirement isn't damaged by the force of a launch. How protected is the Cargo Bay from such forces?
I guess I'll take this one-
Anything that is placed in the payload bay has to meet some pretty stringent criteria in terms of safety and structural integrity. You don't want anything to come loose and damage critical orbiter systems and you don't wan't to damage the payload(s) itself. This means that whatever is back there has to be compatible with the payload bay's mounting devices/carriers and has to be built strong enough to deal with the low frequency vibrations and G-forces experienced during launch, on orbit maneuvering, as well as entry and landing. While these are pretty significant on the shuttle it is a much more benign environment than most unmanned vehicles. The shuttle does not normally exceed 3 Gs. The mounting devices are pretty well understood from an engineering perspective which means that payload designers know exactly what kind of flight environment they are designing for.
So while the intstrumentation may be sensitive it is still built rugged enough to satisfy these demands. Payloads are only allowed to draw certain amounts of power from the orbiter...if they have there own systems for power or propulsion, then they must be designed in such a way as to prevent leaks or contamination. Payloads usually have protective thermal blankets as well as covers for sensitive lenses and so on...
Another factor that protects sensitive equipment is that the payload bay is essentially a clean room environment...this is why you see pictures of people working back there with "bunny suits on". The atmosphere is controlled prior to launch to protect against contamination during fueling as well as from the outside environment. For instance at the Launch Pad you want to maintain a positive atmospheric pressure so that the outside sea-side salt air can not enter the payload bay and cause damage to sensitive systems.
I hope that sort of answers your question.
Mark
Post by: FransonUK on 01/28/2006 11:16 am
Post by: Stardust9906 on 01/28/2006 11:26 am
Quote
FransonUK - 28/1/2006 12:16 PM
What are the Orbiters primarily made of? Steel?
The airframe is made of Aluminium.
Post by: nacnud on 01/28/2006 12:44 pm
Quote
In May 1988 NASA Langley studied a new-technologyapproach to improving the shuttle's payload capability. The designwould allow 9,000 to 18,000 kg of additional payload to be carried inan external payload container or in the orbiter.
Post by: nacnud on 01/28/2006 01:47 pm
It kind of reminds me of boeing SLI concept pictured below, missing from the picuter is the booster stage which is identical but without the payload canister.
Post by: Ben E on 01/28/2006 03:52 pm
Some posters have commented that, when four Shuttles were operational, they were at different stages of processing, it would have been "very difficult" to launch in close proximity to one another. However, there are many examples of missions that were planned to be flown within a couple of weeks of each other - and I'm not just talking about the 'gung-ho', strap-it-on-and-go days of pre-51L.
Back in late 1995, STS-74 lifted-off barely three weeks after STS-73, and only a WEEK after the latter had touched down. Admittedly, STS-73 had been delayed by several weeks itself, which brought the two missions closer together, but this is one of many examples which show it to be technically feasible. Other examples:
* STS-35 lifted-off 17 days after STS-38 in November/December 1990
* STS-39 lifted-off 23 days after STS-37 in April 1991
* STS-55 lifted-off 18 days after STS-56 in April 1993
* STS-68 lifted-off 21 days after STS-64 in September 1994 - and was then followed by ANOTHER launch (STS-66) just 34 days after that.
* STS-70 lifted-off 16 days after STS-71 in June-July 1995.
Each of the above missions featured different orbiters, supposedly at different stages of different processing flows, and yet these short gaps between missions WERE achieved. In the case of STS-64, STS-68 and STS-66, THREE missions - using three separate orbiters - were launched in the space of 55 days.
I do not understand, therefore, how with this breadth of experience of launching orbiters in very close proximity to one another - and even bearing in mind all the lighting constraints needed to view the launch adequately - NASA is now unable to do it again.
Any comments would be appreciated.
Post by: psloss on 01/28/2006 04:39 pm
Quote
Ben E - 28/1/2006 11:52 AMIn each of those cases, the cited launches experienced the several week delay you mention and all were rolled off the pad (with the exception of STS-55), so I think the idea basically comes back to getting a shuttle ready and then setting it aside (so to speak). That's essentially what happened in all of those cases.
Back in late 1995, STS-74 lifted-off barely three weeks after STS-73, and only a WEEK after the latter had touched down. Admittedly, STS-73 had been delayed by several weeks itself, which brought the two missions closer together, but this is one of many examples which show it to be technically feasible. Other examples:
* STS-35 lifted-off 17 days after STS-38 in November/December 1990
* STS-39 lifted-off 23 days after STS-37 in April 1991
* STS-55 lifted-off 18 days after STS-56 in April 1993
* STS-68 lifted-off 21 days after STS-64 in September 1994 - and was then followed by ANOTHER launch (STS-66) just 34 days after that.
* STS-70 lifted-off 16 days after STS-71 in June-July 1995.
STS-35 was shuffled back and forth not just from Pad A to Pad B, but between the VAB and the pads and Columbia between the OPF and VAB. That was "the summer of the hydrogen leak."
STS-39 was rolled back due to ET umbilical door hardware.
STS-55 and STS-68 had main engine shutdowns on the pad.
The STS-70 external tank was attacked by northern flicker woodpeckers.
This is kind of the same "what-if" logistical question I had about having another shuttle ready to do a rescue mission without the CSCS capability that the space station provides. It seems to me that one or the other shuttle would have a decently long "dwell" period, either on the pad or in the VAB, in order to make this possible.
There could also be programmatic issues at present with flying two missions close together -- for example, will there be enough time for the program to thoroughly review all the STS-121 test flight/engineering data for a launch at the end of the May window (which would end in early June) AND still take advantage of the July window for STS-115?
Philip Sloss
Post by: STS-Chris on 01/28/2006 08:45 pm
I saw here that Endeavour is scheduled to fly STS-116, Atlantis STS-117, Endeavour again (STS-118) and then Discovery (STS-119). Is that orbiter flight sequence sure, if STS-121 and 115 are successful?
Are there certain reasons for choosing this orbiter sequence?
Thanks for your answer!
Post by: Ben E on 01/28/2006 11:02 pm
As far as I'm aware, Discovery will fly STS-121 in May 2006 and her next flight will be STS-119 in May 2007. The reason, I believe, is that she is being outfitted to support the new, long-duration power system that utilises the ISS solar arrays. Hence Atlantis and Endeavour will alternately fly the other missions (STS-115 through 118).
No more Orbiter Maintenance Down Periods, though, so after STS-119 the orbiters will pretty much fly in sequence, with Atlantis retiring in 2008 and Discovery and Endeavour flying until the very end.
Thanks for your comments, by the way, Philip. That clarified some of the issues for me - but it does beg one more question. Even setting aside the missions that I cited, which were delayed due to main engine shutdowns etc, I do remember that pre-51L missions COULD be launched at intervals much shorter than the 4-6 month processing flows needed by orbiters today. In 1985, for instance, Challenger and Discovery averaged 2-month turnarounds. Was NASA just cutting corners in their processing flows which it opted not to do in the wake of 51L? Or could such short turnarounds still be possible today?
Post by: Chris Bergin on 01/29/2006 09:50 am
Quote
Ben E - 29/1/2006 12:02 AM
STS-Chris,
As far as I'm aware, Discovery will fly STS-121 in May 2006 and her next flight will be STS-119 in May 2007. The reason, I believe, is that she is being outfitted to support the new, long-duration power system that utilises the ISS solar arrays. Hence Atlantis and Endeavour will alternately fly the other missions (STS-115 through 118).
No more Orbiter Maintenance Down Periods, though, so after STS-119 the orbiters will pretty much fly in sequence, with Atlantis retiring in 2008 and Discovery and Endeavour flying until the very end.
Thanks for your comments, by the way, Philip. That clarified some of the issues for me - but it does beg one more question. Even setting aside the missions that I cited, which were delayed due to main engine shutdowns etc, I do remember that pre-51L missions COULD be launched at intervals much shorter than the 4-6 month processing flows needed by orbiters today. In 1985, for instance, Challenger and Discovery averaged 2-month turnarounds. Was NASA just cutting corners in their processing flows which it opted not to do in the wake of 51L? Or could such short turnarounds still be possible today?
Well Griffin reckons the 4.5 missions per year with three Orbiters is possible, so it's not vastly different with the turnarounds of old.
Post by: Ben E on 01/29/2006 11:31 am
The 1997 roster was:
STS-81 Atlantis Shuttle-Mir 12 January
STS-82 Discovery Hubble 11 February
STS-83 Columbia MSL-1 4 April
STS-84 Atlantis Shuttle-Mir 15 May
STS-94 Columbia MSL-1 Reflight 1 July
STS-85 Discovery CRISTA-SPAS-2 7 August
STS-86 Atlantis Shuttle-Mir 25 September
STS-87 Columbia USMP-4 19 November
You could probably argue that the MSL-1 reflight was easier because they were reprocessing the same payload, but casting that one aside, there would still have been seven missions achieved by only three orbiters. Why can't they do it again?
Post by: psloss on 01/29/2006 12:06 pm
That's a good question for the program folks to answer, particularly people who have been in the program for a while. From a pre-Challenger to now point of view, I would guess that you're pretty close to the sense I get -- which is that the orbiters and all the hardware get a lot more "tender loving care" now. Some of that has to be lessons learned during the program.
Another factor was noted by the the CAIB, which is that even given the large shuttle workforce, it was trimmed a lot during the Goldin years in the 90s. I don't believe that 3-shifts, 7-days a week is standard practice anymore at KSC -- hopefully someone here can say for certain.
Your point though about 1997 is taken, though; I would also point to the early ISS assembly sequence that occured in 2000-2001 after a very slow period between the Zarya and Zvezda module launches. There, you had an eight flight sequence beginning with ISS 2A.2B in September 2000 (STS-106) through ISS 7A.1 in August 2001 (STS-105) -- also with three orbiters.
It's pure speculation on my part, but I think a period like that is possible again, given some momentum from a series of clean, successful missions -- there's a similar "assembly heavy" sequence of missions ahead right now. I wouldn't expect it to become a standard practice or expectation again, though.
Philip Sloss
Post by: psloss on 01/29/2006 12:15 pm
Quote
Ben E - 28/1/2006 7:02 PMAnother quickie point: Discovery is slightly heavier than Atlantis and Endeavour, so it "couldn't" fly the 12A/STS-115 or 13A/STS-117 flights, anyway. The P3/P4 and S3/S4 trusses have a rotating joint that makes them heavier than the other trusses with solar array wings (P6 and S6, the former already on-orbit).
As far as I'm aware, Discovery will fly STS-121 in May 2006 and her next flight will be STS-119 in May 2007. The reason, I believe, is that she is being outfitted to support the new, long-duration power system that utilises the ISS solar arrays. Hence Atlantis and Endeavour will alternately fly the other missions (STS-115 through 118).
No more Orbiter Maintenance Down Periods, though, so after STS-119 the orbiters will pretty much fly in sequence, with Atlantis retiring in 2008 and Discovery and Endeavour flying until the very end.
("Couldn't" in quotes, because I'm confident that if they needed to use Discovery for the rotary joint trusses, they could make it happen; there are better options, though.)
Philip Sloss
Post by: Ben E on 01/29/2006 12:29 pm
Yes, Discovery hasn't really ferried much 'heavy' stuff up at all so far. I was just looking at the ISS assembly sequence so far and most of the 'heavy' stuff - solar arrays, Destiny, Unity, Quest and truss segments - have been on Atlantis or Endeavour.
Maybe, as with fashion, Discovery is the 'new' Columbia = the heavy old bird that no-one wants to use. I hope not, though.
STS-96 - Spacehab
STS-92 - Z-1 truss (only a fairly-light segment though)
STS-102 - MPLM
STS-105 - MPLM
STS-114 - MPLM
STS-121 - MPLM
I see what you mean. Nothing too huge or heavy so far for Discovery.
Post by: Chris Bergin on 01/29/2006 12:32 pm
Of course it's not the same as 1997, but taking into account two orbiters completing this cycle, in a RTF cycle, mitigating circumstances level out here. That's my point.
STS-115 – Atlantis – July 1
STS-116 – Endeavour – October 1
STS-117 – Atlantis – December 7
2007
STS-118 – Endeavour – March 15
Post by: Ben E on 01/29/2006 01:44 pm
Just out of curiosity, and slightly off at another tangent, do you (or Philip) know why the STS-116 'core' crew has been increased from an original size of four in pre-107 days to a current crew of six?
Original 'core' crew:
Terry Wilcutt, Commander
Bill Oefelein, Pilot
Bob Curbeam, Mission Specialist
Christer Fuglesang, Mission Specialist
Current 'core' crew:
Mark Polansky, Commander
Bill Oefelein, Pilot
Bob Curbeam, Mission Specialist
Christer Fuglesang, Mission Specialist
Joan Higginbotham, Mission Specialist
Nick Patrick, Mission Specialist
There doesn't appear to be a 'different' payload that might necessitate the extra crew members - it's still listed as the P-5 spacer and the Spacehab cargo module - and, as far as I'm aware, there are no more EVAs added which might require an extra two-person EVA team. What will the two extra crew members be doing?
Any ideas?
Post by: FransonUK on 01/29/2006 03:23 pm
Post by: mkirk on 01/29/2006 04:53 pm
Quote
FransonUK - 29/1/2006 10:23 AM
There's a question. How is it determined how many crew go on a flight? What's the minimum, what's the maximum?
CURRENT flight rules specify the minimum shuttle crew as 4 and the nominal maximum as 7. For contingency rescue missions you would have a total of 11 crew onboard for re-entry (4 going up plus the 7 rescued crew members). For the shuttles first four test flights only 2 crew members were on board.
Mark
Post by: Chris Bergin on 01/29/2006 05:02 pm
Post by: mkirk on 01/29/2006 05:06 pm
Quote
Chris Bergin - 29/1/2006 12:02 PM
How would they configure a crew of 11 on the flight and middeck? Apparently being strapped in not needed for re-entry? I say that was there's a story going around about John Young having to tell off one of the astronaunts on an early flight standing up on the flight deck during re-entry with a video camera? :)
Hey Chris-
The extra crew members who don't get the traditional seats will use a recumbent seat mounted to the floor with their feet in the forward lockers. I'll try and dig out one of the NASA photos of this and post here.
As far as standing I believe Story was the first culprit on STS-6.
Mark
Post by: Chris Bergin on 01/29/2006 05:12 pm
Post by: braddock on 01/30/2006 12:55 am
Quote
mkirk - 29/1/2006 1:06 PM
As far as standing I believe Story was the first culprit on STS-6.
Apparently correct. He stood throughout reentry on STS-6 to prove that it could be done in an emergency (at least that was his excuse).
I found an account at: http://www.spacestory.com/flyingdr.htm , quoted below:
Quote
During re-entry into the Earth's atmosphere, Dr. Musgrave stood up in Challenger's cabin, an action usually prohibited by standard operating procedure. The question came up at the press conference, and Weitz said, "Sure, Story did it on the spur of the moment, but we all knew what he was doing and nobody's quarreled with him -- at least until now."
Dr. Musgrave didn't comment at the press conference, but now he explained, "I was conducting my own experiment. The whole flight had been so totally exhilarating and I was on such a high that I decided to stand throughout re-entry. It's my nature to press and push, to go beyond what's expected. I had my Hasselblad camera and I was taking some photos. Also, I wanted to prove that you can stand while going from zero gravity back into gravity. That's important if an astronaut ever has to leave the top deck and go below to throw a switch or circuit breaker. I wanted to show that the cardiovascular system doesn't have any problem going back into gravity and that you don't have to be strapped down.
"My standing was smooth and steady, and it shows how the STS system is maturing. We all had total confidence. Standing up throughout re-entry, instead of being strapped down, was the perfect end to a perfect trip. I was having fun, as always.
Musgrave is a fascinating person; I've had the opportunity to meet him a couple times. A few years ago I even had the unlikely privilege of helping Story change a tire in the middle of the Mojave...I remember he kept calling the tire iron the "actuator". :)
Post by: Ben E on 01/30/2006 12:16 pm
I know that crews need at least CDR, PLT, MS1 and MS2. After that, it's a big grey area, except that missions requiring above three EVAs do generally have four EVA Mission Specialists. Before the installation of Canadarm2, most ISS assembly missions (carrying major components) required an additional Mission Specialist to operate the RMS (Currie on 2A, Wakata on 3A, Garneau on 4A, Ivins on 5A, Kavandi on 7A, Ochoa on 8A, Magnus on 9A). What now confuses me is that many upcoming missions to install truss segments have four EVA Mission Specialists, but no dedicated RMS operator.
STS-115 Tanner, Burbank, MacLean, Stefanyshyn-Piper (working in two alternating pairs)
STS-116 Curbeam, Fuglesang, Higginbotham, Patrick (working in two alternating pairs)
STS-117 Reilly, Mastracchio, Forrester, Swanson (working in two alternating pairs)
Do they no longer need RMS operators - is it now exclusively done by Canadarm2 and, hence, by an ISS expedition crew member?
Interesting also that some missions with similar payloads had different numbers of astronauts. ATLAS-1 back in 1992 had a crew of seven, including two Payload Specialists, whereas ATLAS-2 and ATLAS-3 had five and six astronauts, respectively. Moreover, the last two ATLAS missions didn't have Payload Specialists. Why?
Similarly, Shuttle-Mir missions had different crew numbers. Leaving aside the NASA astronauts going up and down for long-duration stays, 'core' SMM crews were as follows:
SMM-1 Gibson, Precourt, Baker, Harbaugh, Dunbar (5)
SMM-2 Cameron, Halsell, Hadfield, Ross, McArthur (5)
SMM-3 Chilton, Searfoss, Sega, Clifford, Godwin (5)
SMM-4 Readdy, Wilcutt, Apt, Akers, Walz (5)
SMM-5 Baker, Jett, Wisoff, Grunsfeld, Ivins (5)
...but then...
SMM-6 Precourt, Collins, Clervoy, Noriega, Lu, Kondakova (6)
SMM-7 Wetherbee, Bloomfield, Titov, Parazynski, Chretien, Lawrence (6)
SMM-8 Wilcutt, Edwards, Reilly, Anderson, Dunbar, Sharipov (6)
SMM-9 Precourt, Gorie, Chang-Diaz, Lawrence, Kavandi, Ryumin (6)
Why did the last four SMMs require an extra crew member? All involved dockings and crew/payload transfers and all carried more-or-less the same amount of consumables in similar-sized double Spacehabs. In fact, SMM-9 had a SMALLER Spacehab (hence less cargo to be moved to and from Mir), yet still required the larger crew size?
Is it more to do with office and international politics (ie getting Ryumin a seat) than how many astronauts are officially 'needed'?
Post by: psloss on 01/30/2006 11:54 pm
Regarding shuttle RMS operations, particular now, that I seem to recall that the PLT has flown the arm (and perhaps both arms) on recent ISS missions. Also, the boom currently is in the way while the shuttle is docked, so the shuttle arm has to hold it in a safe position after handoff from the SSRMS.
Not sure about the other questions, though Ryumin's seat on STS-91 did seem a little less, uh, technical. There may have also been a dynamic going on (at the time of the last couple of Mir flights) with the Russians wanting to prolong Mir's life while the U.S. wanted to focus more on getting the ISS started. Given the intention for Mir to be de-orbited, internal/long-term logistics might not have been such a high priority in the last two American increments.
Philip Sloss
Post by: Ender0319 on 01/31/2006 12:59 am
On the upcoming STS-121 mission, most of the SRMS activities will be performed by Lisa Nowak and Stephanie Wilson. They will also be peforming SSRMS activities and neither is the CDR or PLT.
A lot of the RMS assignments defy rhyme and reason and are mostly due to crew resources and limitations. Things sure will become more interesting now that the OBSS (Orbiter Boom Sensor System) is the primary "tool" for performing inspections on-orbit.
Post by: Jamie Young on 01/31/2006 01:54 am
The Shuttle has really shown the robotic arms work well and are an invaluable tool on the Shuttle and ISS. Could they eventually become pre-programmed and controlled from Earth, maybe?
I know we won't see this on the Orbiters, but would it have been possible to eventually take man out of the loop, with a Buran style unmanned flight and automated robotic arms, for say a HSM.
Please understand this is just theory, it won't happen with four years of STS remaining.
Post by: psloss on 01/31/2006 02:18 am
Thanks for the information,
Philip Sloss
Post by: nacnud on 01/31/2006 08:32 am
Post by: nacnud on 01/31/2006 08:46 am
Quote
International Space Station Status Report: SS05-027
Allard Beutel
Headquarters, Washington
(Phone: 202/358-4769)
James Hartsfield
Johnson Space Center, Houston
(Phone: 281/483-5111)June 3, 2005 STATUS REPORT: SS05-027
A new capability is being added to the operation ofthe International Space Station. A final round of tests to commissionremote control of the Station's Canadarm2 robotic arm from the groundwas completed this week.
The 60-foot arm was maneuvered byground control today to move in, latch onto a fixture on the exteriorof the Station, release and move back out. The tests were the secondand most complex remote control operations of the arm performed fromthe ground. The first set of tests completed earlier this year involvedonly basic movements. Completion of these two phases of commissioningwill qualify the ground control capability to be considered for useduring future Station operations.
During the tests, the arm wascontrolled by the robotics officer in the Space Station Flight ControlRoom of Mission Control. Aboard the Station, Flight Engineer and NASAStation Science Officer John Phillips monitored the activity. Normally,the arm is controlled by the Station crew using a robotics workstationin the Destiny Laboratory.
Post by: Hotol on 01/31/2006 10:25 am
Post by: Ben E on 01/31/2006 11:48 am
Post by: nacnud on 01/31/2006 01:33 pm
Post by: Hotol on 01/31/2006 01:41 pm
Post by: Ben E on 01/31/2006 03:07 pm
STS-58 was Columbia, which had the internal airlock. You're right: the other orbiters would have a lot more internal room in their middecks because the airlock is now outside in the payload bay.
Still a tight squeeze though.
Many thanks.
Post by: BogoMIPS on 01/31/2006 08:11 pm
How close to maxxed out is the cargo capacity of the Shuttle Carrier Aircraft when hauling a shuttle? I know it's limited to about 1000 miles due to fuel consumption from the mass involved...
Post by: Ender0319 on 02/01/2006 01:59 am
The SRMS is too old (for lack of a more gratifying term) of a design to be allowed to be controlled from the ground. So, for as long as there is a need for the SRMS, there must be a human-in-the-loop to operate it.
Before the HSM was put back on the schedule, Goddard was looking at a remotely operated robotic arm to service HST. I believe the technical, political, and economic challenges may have been too great to permit a tele-robotic mission. Perhaps in the future, this can be considered.
Quote
Jamie Young - 30/1/2006 8:54 PM
Stupid question from me time.
The Shuttle has really shown the robotic arms work well and are an invaluable tool on the Shuttle and ISS. Could they eventually become pre-programmed and controlled from Earth, maybe?
I know we won't see this on the Orbiters, but would it have been possible to eventually take man out of the loop, with a Buran style unmanned flight and automated robotic arms, for say a HSM.
Please understand this is just theory, it won't happen with four years of STS remaining.
Post by: mkirk on 02/01/2006 10:16 pm
Quote
BogoMIPS - 31/1/2006 3:11 PM
A question I thought of today...
How close to maxxed out is the cargo capacity of the Shuttle Carrier Aircraft when hauling a shuttle? I know it's limited to about 1000 miles due to fuel consumption from the mass involved...
Here is a link to the fact sheet for the SCA. The real problem for the SCA's performance is that with the orbiter attached it has to fly at such low altitudes...around 15,000 feet...this means it eats up gas and it has to skirt around all the cumulus cloud buildups and weather which in turn kills its range capability. During ferry flights another aircraft is designated as the "Pathfinder" flys ahead of the SCA to scope out a favorable root for the SCA to fly.
I also included a couple of pictures of the SCA. The one picture is the aft attchement point for the orbiter with some special instructions on it. You would think that since NASA hires the best and brightest that such instructions would not have to be spelled out:)
Mark
Post by: STS-Chris on 02/02/2006 03:24 pm
"Black side down"
^^ Very good!
Nice Pics. :)
Post by: Jonesy STS on 02/02/2006 03:26 pm
Post by: nacnud on 02/02/2006 04:35 pm
Post by: STS-Chris on 02/02/2006 04:44 pm
How is the status of the external tank debris problem?
Is it going to be solved?
Is a launch of STS-121 in May realistic?
Post by: Chris Bergin on 02/02/2006 08:12 pm
All your questions are answered if you just look around a little more.
http://forum.nasaspaceflight.com/forums/forum-view.asp?fid=2
Welcome to the site :)
Post by: Captain Scarlet on 02/03/2006 03:23 pm
Post by: mkirk on 02/03/2006 07:12 pm
Quote
Captain Scarlet - 3/2/2006 10:23 AM
What will happen to the SCAs after the Shuttle retirements?
Actually that is a question a lot of the Aircraft Operations people have been asking among other things. What happens to the Shuttle Training Aircraft (STA), the Shuttle Carrier Aircraft (SCA), and the T-38 fleet. It is just to soon to tell, but I know some of those folks are a little concerned about there jobs as the transition to the CEV program begins. Presumably the T-38 fleet will stick around but perhaps it will be a smaller fleet...this would really be dependent on the required size of the Astronaut Corps for CEV. It is just to valuable a tool for crew coordination experience in a high stress flight environment and a transportation tool. The C-9 which replaced the old "vomit comet" (KC-135) will still be needed but who knows what will happen to the STA and SCA. They might be able to find a home or use in flight research...
It is just to soon to know what is going to happen.
Mark
Post by: Donna Spaceships on 02/04/2006 11:00 am
Post by: Jamie Young on 02/04/2006 05:27 pm
Quote
Donna Spaceships - 4/2/2006 6:00 AM
How different is it to fly a SCA, compared to a normal 747?
I think they'd be a lot of difference, with all that weight, not only just the orbiter, but the ballast inside the SCA.
Post by: Heather on 02/05/2006 11:40 am
I have a question. You know the ET is the one part of the Shuttle that isn't reused, has anyone got video or images of it burning up after being seperated? I've only seen images of it falling away. How long until it starts to burn up and how long does it take? Is there nothing left, or do some parts still splash into the ocean?
Post by: psloss on 02/05/2006 01:25 pm
Quote
Heather - 5/2/2006 7:40 AMThere is video of some ET re-entries on a few low-inclination, direct-insertion launches (I believe). If I recall correctly, I saw ET breakup video broadcast on CNN from the STS-41C launch and also amateur video on the STS-37 launch from I think Maui.
Hello, been a guest here for a long time. Great site.
I have a question. You know the ET is the one part of the Shuttle that isn't reused, has anyone got video or images of it burning up after being seperated? I've only seen images of it falling away. How long until it starts to burn up and how long does it take? Is there nothing left, or do some parts still splash into the ocean?
Philip Sloss
Post by: Heather on 02/05/2006 01:32 pm
Post by: psloss on 02/05/2006 01:41 pm
Quote
Heather - 5/2/2006 9:32 AMWish I could say conclusively, but I don't know.
Thank you, but are they available on the internet to view?
Post by: Chris Bergin on 02/05/2006 02:02 pm
Post by: psloss on 02/05/2006 02:12 pm
Post by: Stardust9906 on 02/05/2006 03:25 pm
Quote
psloss - 5/2/2006 2:25 PMQuoteHeather - 5/2/2006 7:40 AMThere is video of some ET re-entries on a few low-inclination, direct-insertion launches (I believe). If I recall correctly, I saw ET breakup video broadcast on CNN from the STS-41C launch and also amateur video on the STS-37 launch from I think Maui.
Hello, been a guest here for a long time. Great site.
I have a question. You know the ET is the one part of the Shuttle that isn't reused, has anyone got video or images of it burning up after being seperated? I've only seen images of it falling away. How long until it starts to burn up and how long does it take? Is there nothing left, or do some parts still splash into the ocean?
Philip Sloss
I found a couple of photo's of the STS-41C tank re-entry at http://satobs.org/re-entry.html
Post by: Flightstar on 02/05/2006 06:58 pm
Post by: HKS on 02/07/2006 12:03 pm
What decides witch launchpad to use on KSC? STS-114 used 39B, and STS-121 is also going to use 39B, when will 39A be used?
Post by: anik on 02/07/2006 04:25 pm
Quote
HKS - 7/2/2006 4:03 PM
Is there any words on how results were after the repair techniques on shuttle RCC panels and tiles preformed in space on STS-114?
I saw only this preliminary test results in "NASA Space Station On-Orbit Status 30 July 2005":
"The TPS DTO activities in the Shuttle payload bay began at ~6:45am and extended thru 8:16am EDT. [Preliminary test results: The NOAX (Non-Oxide Adhesive eXperimental) demo on the RCC porosity sample showed some swelling after its application to cracks. When smoothed out with the spatula tool, swelling persisted, estimated by the EV crew at 1/32 of an inch. When applied to gouges, bubbling of 1/16 inch was observed in the NOAX. The material was hard to shape inside the gouge and tended to want to come out, or roll right off of the spatula. The temperature of the test sample was recorded to be 6.7 deg C. Testing with the sample planned for later arcjet testing on the ground had to be rescheduled due to falling behind in the EVA timeline. The EW (Emittance Wash) application was performed on two different tile samples. Some evidence of minor bubbling was detected. The EW material was described as carbonated at first when coming out of the gun, however this effect quickly ceased. The material was applied directly in the body of the tile damage crevices with the gun applicator and with a foam brush tool used to coat the edges of the tile damage.]"
Post by: mkirk on 02/07/2006 05:02 pm
Quote
HKS - 7/2/2006 7:03 AM
What decides witch launchpad to use on KSC? STS-114 used 39B, and STS-121 is also going to use 39B, when will 39A be used?
Right now Pad A is udergoing a maintenance down period. They have been repainting the structures, they removed the rest of the overhead crane from the Fixed Service Structure and so on...The plan (as I last understood it) is to bring Pad A on line late this year/early next year and then it will be Pad B's trun for maintenance. I believe they will actually use this time to begin modifications to PAD B to support the CLV. This means that PAD A will support the rest of the STS schedule.
Mark
Post by: DaveS on 02/08/2006 09:51 am
Post by: HKS on 02/08/2006 11:37 am
And, why do they need several weeks on the launch-pad before launching?
Post by: mkirk on 02/08/2006 06:19 pm
Quote
DaveS - 8/2/2006 4:51 AM
Can someone tell me what these circles around the SRB nosecone is? I know that those in a square pattern is the forward Booster Seperation Motors(BSMs), but what about the others?
Those are static pressure ports similar to what you would find on an airplane. They are used for the altitude sensing system during recovery.
Mark
Post by: SimonShuttle on 02/09/2006 01:39 pm
Post by: Jim on 02/09/2006 01:58 pm
Quote
SimonShuttle - 9/2/2006 8:39 AM
The SRBs always seem to seperate very much together in the way they come away from the ET. They also appear to be still firing for a good 10-15 seconds after seperation. How is this timed? Always at a set time, or a set point of ascent, or at a set point of remaining propellant?
When the chamber pressure is less than 50psi. There is residual propellant still burning but providing less thrust than the weight of the casings. There is occasional chuffing even when under chute.
Post by: Mark Max Q on 02/09/2006 02:13 pm
Post by: dmc6960 on 02/09/2006 08:09 pm
Post by: Jim on 02/09/2006 08:11 pm
Post by: Davie OPF on 02/09/2006 10:40 pm
Quote
Jim - 9/2/2006 3:11 PM
shuttle airlock vents into space
Yes. There should be images of how it is exposed from STS-114 on orbit operations via some threads here.
Post by: dmc6960 on 02/10/2006 02:49 am
Post by: Jim on 02/10/2006 04:43 am
Post by: Rob in KC on 02/13/2006 05:46 pm
Post by: Jim on 02/13/2006 06:00 pm
Quote
Rob in KC - 13/2/2006 12:46 PM
Can someone explain why the Orbiter uses APUs, as opposed to heavy duty batteries?
Power density. At the time, APU was the highest and cheapest power density (hp/lb) available. The SRB's use the same system but they are call HPU's. Titan's SRMU's used a solid cartridge powered HPU's
Most launch vehicles power their hydraulics from a power takeoff on the engine turbopowers. Shuttle doesnt have this luxury during entry. So an alternative source was required.
Post by: Rob in KC on 02/13/2006 10:49 pm
Post by: mkirk on 02/13/2006 11:39 pm
A side note: The SSP (space shuttle program) went pretty far toward adopting the EAPU (electric auxilliary power unit). This was a shuttle upgrade that was officially taken off the table when the decision to stop flying shuttles by 2010 was made. After that it didn't make sense to spend the money on the change.
Mark
Post by: Ben E on 02/17/2006 10:38 pm
Post by: Jim on 02/18/2006 02:21 pm
Post by: Firestarter on 02/18/2006 06:04 pm
Quote
Ben E - 17/2/2006 5:38 PM
Presumably also the upgrades such as 'smart cockpits' have gone now, too? Will NASA use any of this technology for the CEV?
I'm sure they could utlize some of the realiable elements of the Orbiters? Flight experience etc?
Post by: Jim on 02/18/2006 11:31 pm
Quote
Firestarter - 18/2/2006 1:04 PMQuoteBen E - 17/2/2006 5:38 PMPresumably also the upgrades such as 'smart cockpits' have gone now, too? Will NASA use any of this technology for the CEV?I'm sure they could utlize some of the realiable elements of the Orbiters? Flight experience etc?
Shuttle was 70's technology and had trouble with maintaining expertise in outdated systems. CEV will have state of the art avionics. Not much from the shuttle is applicable to the CEV
Post by: Chris Bergin on 02/19/2006 10:53 am
Post by: Jim on 02/19/2006 01:00 pm
For OSP, they were looking at the computers used in the 777.
A computer that is used in other porgrams would have the benefits of a logistics pipeline, larger population to study failures, personnel experience, etc
Post by: mkirk on 02/20/2006 12:44 am
Quote
Do Shuttles Dream - 17/2/2006 5:58 PM
This is awesome. So many things I've always wanted to know and now getting to know!
Question. Nine readout displayes. Two on the right and two on the left look the same, and I suppose that's so the pilot and commander aren't looking over each other for info readouts.
What's the five in the middle? General Purpose Computers I bet? What's the upward curving line showing?
Bump from another forum thread.
Here are a couple of pictures of the front office of the orbiters. ONLY TRUE SHUTTLE GEEKS NEED TO READ ANY FURTHER.
The 9 screens on the front console are called MFD (multi function displays) and were installed as part of the “Glass Cockpit Upgrade” or MEDS (multifunction electronic display system). All of the orbiters now have this. With these MFDs any display is available on any screen. However in practice 3 of the 5 MFDs on the center console (between the pilot and commander) are laid out in the same manner as the old cockpit. It was on this panel that the three CRTs used to display information from the GPCs (general purpose computers) were located. The left top screen was called CRT 1, the top right was CRT 2, and the center was called CRT 3. The same naming convention is used on these screens today even though they could be displayed anywhere.
There are over 100 different GPC displays available to the CRTs that give trajectory information, systems status, and so on. The other 6 MFDs are used to display digital versions of the old analog gauges (often called the “steam gauges”).
In the big picture you can see the cockpit set up as if the orbiter just landed. The primary flight instruments are in front of the commander and pilot. CRT 1 is showing the Horizontal Situation Display which is a God’s eye view of the HAC (heading alignment cone) and touchdown point. CRT 2 shows the Vertical Situation Display which is a profile view of the approach trajectory. CRT 3 shows the backup flight computers version of the same Vertical Situation Display. The other two MFDs on the center console show the SPI (surface position indicator) on the lower left and the APU/hydraulic gauges on the lower right.
AEPFD, the 3rd picture (description):
This is a composite version of the displays on the two screens in front of the commander and pilot. The two screen version is generally not used. I always preferred the composite version because it makes cross checking the instruments easier (i.e. less eye movement)
This Picture shows from left to right on the top half: the airspeed tape in knots (279) with mach number in the square box below it, the alpha or angle of attack (9.8), the 8 ball which shows a left bank of 53 degrees and a nose down pitch of 24 degrees, the H tape shows altitude in thousands of feet (24,000) and the next one called H-dot, shows vertical velocity in feet per second (-315).
The Bottom half shows the G-meter (1.6), the HSI (heading selector indicator…basically a compass with current heading (311 degrees) the selected runway is Northrup 17 (which is at Whitesands) and the left scale is the glide slope.
If you want to know about the others just ask. I don't want to write a novel on this post unless people are interested.
Mark
Post by: Jonesy STS on 02/20/2006 04:57 pm
Post by: STS Tony on 02/20/2006 05:37 pm
Are the alarm warnings above CRT3 on these pictures?
Post by: Jim on 02/20/2006 05:58 pm
Post by: mkirk on 02/20/2006 07:00 pm
Quote
STS Tony - 20/2/2006 12:37 PM
Mark, this is awesome. Thank you.
Are the alarm warnings above CRT3 on these pictures?
Yes. Here is a look at the Caution & Warning lights in this picture. The lights are just a small portion of the overall warning system. There are about a 150 fault messages ( I am too lazy to count so that could be a low ball guess) that can be anunciated by the GPCs (general purpose computers) either in conjunction with or independent of the lights.
In training you get so used to all the warnings going off that there is a real danger of missing important life threating cautions. When the master caution sounds/illuminates the normal response is to silence the alarm by pushing the MASTER CAUTION light button on the eyebrow panel (i.e. dashboard above the flight instruments), and then looking at the actual warning on the light panel and on the CRT for the GPC. After a lot of training a crew member can almost react in a Pavlovian manner by pushing the button the second the alarm sounds. Sneaky training instructors will usually create problems that occur almost simultaneosly in an attempt to see if the crewmember reacts to one problem without realizing there were maybe 1 or 2 more.
Every one falls for it at some point Astronauts and Instructors both.
Not all warnings are serious, some are expected advisories...the hard part of training is learning to be able to distinguish between "no problem" and "you are having a really bad day".
During the countdown for launch at about T-2 minutes 30 seconds you will hear a call from the Launch Control Center to the crew to "clear the caution and warning memory". The crew will look at the message buffer and make sure that the 5 or 6 messages that occured during the count were the expected ones and then they will clear the buffer so that any portential new warnings during launch are not confused with ones already in the system.
Some trivia:
During the very last "integrated ascent entry simulation" with the mission control team...typically the day before the crew heads to the Cape from Houston...the instructors will usually let the crew have a mild/normal last run (normally a sim will have 4-5 runs total during the session) where nothing goes very wrong. This sim is kind of a dry run of the launch and allows the crew to end there training on a positive note. At the very end it is tradition for the instructors to light up that quare matrix in such a way that the lights that are illuminated, spell out the mission number (ex 88 for STS-88). This has gotton more difficult to do now that the program is well into the tripple digits.
Mark
Post by: Chris Bergin on 02/20/2006 07:45 pm
Here's a question Mark, going off what we're seeing in front of us here CWF7 lights, what would Commander Collins of been seeing for her to call back on the loop, during STS-93: "This is Columbia, we're in the roll, we've got a fuel cell (glitch) level one."
Top middle on the panel? (Fuel Cell Reac)
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=442&start=1
Fascinating stuff :)
Post by: Jamie Young on 02/20/2006 10:28 pm
Post by: David AF on 02/20/2006 10:34 pm
To compare, here's the inside of what I have to deal with. F-22 Raptor. Awesome bird.
Post by: psloss on 02/20/2006 10:41 pm
Quote
Chris Bergin - 20/2/2006 3:45 PMI'm interested in Mark's reply, too, because I'd like to know more about how this was "anunciated" to the crew, but I believe that what the CDR said was "...we've got a fuel cell pH number one" -- which I would assume to be a pH "message," but the shuttle folks would know whether this was caution and warning or something else.
No wonders this thread jumped by 400 page views in a few hours.
Here's a question Mark, going off what we're seeing in front of us here CWF7 lights, what would Commander Collins of been seeing for her to call back on the loop, during STS-93: "This is Columbia, we're in the roll, we've got a fuel cell (glitch) level one."
From the MER reports at JSC's web site:
http://www.jsc.nasa.gov/news/columbia/STS-93_launch_report.pdf
Quote
Approximately 5 seconds after the liftoff of the vehicle, an electrical short of
approximately 0.5-second duration occurred on AC bus 1. Coincident with the short, the
SSME 1 (center engine) controller A and the SSME 3 (right engine) controller B were
disqualified. Post ascent, the crew was asked to check the SSME controller circuit
breakers on panel L4 and they reported that none had opened.
Data evaluation indicated that the short had occurred on phase A of AC bus 1. An
extensive review of the Orbiter components that were being powered by AC bus 1
during the event was performed. This review showed that there were effects of the
resulting AC bus 1 undervoltage caused by the short, but all of the Orbiter equipment
operating at the time of the short operated nominally following the short. One of the
effects seen was the high pH indication received by fuel cell 1 when the sensor
performed a self test that was initiated by the undervoltage transient.
During flight day 3, the crew reported that the AC bus 1 phase A circuit breaker for
SSME 1 controller A was actually open and transmitted photographs of the circuit
breaker to the ground.
(My emphasis)
Philip Sloss
Post by: psloss on 02/20/2006 11:01 pm
Quote
mkirk - 20/2/2006 3:00 PMThese discussions always remind me of the legend of the Apollo 12 launch, which electrically discharged itself a couple of times in the first minute of launch. Can't find the exact reference, but I thought I read somewhere that after the two "lightning strikes," either Dick Gordon or Alan Bean said to Pete Conrad about the caution and warning display lights "they're all on." (Not much help when they're all on!) Here's a quote I found online from (sad to say 'late') Pete Conrad:
Not all warnings are serious, some are expected advisories...the hard part of training is learning to be able to distinguish between "no problem" and "you are having a really bad day".
http://www.pcug.org.au/~jsaxon/space/book/After11.htm
Quote
Conrad: "I had a pretty good idea what had happened. I had the only window at the time the booster protector covered the other windows and I saw a little glow outside and a crackle in the headphones and, of course, the master caution and warning came on immediately and I glanced up at the panel and in all the simulations they had ever done they had never figured out how to light all eleven electrical warning lights at once by Golly, they were all lit, so I knew right away that this was for real.(I can almost picture him saying this with a smile on his face...)
Philip Sloss
Post by: STS Tony on 02/21/2006 12:04 am
Seems like an awfully large amount of things to look at during flight. How long does it take to train someone to be competent in 'flying an Orbiter'? Is it the hardest 'plane' to learn?
Post by: mkirk on 02/21/2006 01:04 am
Quote
Jamie Young - 20/2/2006 5:28 PM
Is there a similar sort of display at JSC so they can see what the commander and pilot are seeing in real time?
Yes the flight controllers can see the same data and a whole lot more. There is an enormous amount of data downlinked that the crew can not see, this is why MCC (the mission control center) plays such a crucial role in mission operations. They really do function as an integrated part of the "crew concept" allbeit from the ground. In the MCC there are various dispalys and formats; some mimic the crew displays, some are in table form, some come out in graph or strip charts form, and in many cases they can be set up in a, system specific, schematic format.
The first picture I attached is of the FLIGHT DIRECTOR CONSOLE, in this case Leroy Cain: on the left screen you can see a table like display that shows data for various subsystems. At the top of the screen, it looks like he as the scrolling list of GPC inputs by the crew...this shows every key stoke the crew members make into the computers. On the right hand side of the right screen you can see a display that mimics the 8 ball (artificail horizon) just like in the cockpit. Under that are copies of the tapes that the crew has for airspeed, altitude, angle of atack, veritival velocity and so on.
In the second picture you see Ken Ham, "Hawk" and Rick Sturckow, "C J" siting at the CAPCOM CONSOLE. In front of Hawk you see a similar set up. He also has the cockpit tapes up in the upper right corner.
Out of frame to the right of CJ are two more screens in which he has the same type of displays as well as on board GPC versions of the Horizontal and Vertical situation displays.
You may also notice a lot of orange matrix displays at everyones console; this is the DVIS (digital voice information system) and it allows each controller to select the loops he/she wants to monitor and at what relative volume level. By my count it looks like Hawk has nine different communications loops dialed up.
I wish I had some better copies of these displays with me on my laptop...maybe I can dig them out at a later date.
Mark
Post by: Jim on 02/21/2006 01:06 am
Quote
STS Tony - 20/2/2006 7:04 PMWow, thanks for the close up.Seems like an awfully large amount of things to look at during flight. How long does it take to train someone to be competent in 'flying an Orbiter'? Is it the hardest 'plane' to learn?
Remember, the Orbiter has a crew. Yes, CDR and PLT are responsible for "flying" the shuttle during ascent and entry, but they get help from one of the other astronauts, who is designated as the "flight engineer". Plus the crew has Mission Control "looking over their shoulders." The crew trains more per flight than other vehicles. Look at what "David AF" flies and he does it all by himself.
Post by: mkirk on 02/21/2006 01:23 am
Quote
Chris Bergin - 20/2/2006 2:45 PM
No wonders this thread jumped by 400 page views in a few hours.
Here's a question Mark, going off what we're seeing in front of us here CWF7 lights, what would Commander Collins of been seeing for her to call back on the loop, during STS-93: "This is Columbia, we're in the roll, we've got a fuel cell (glitch) level one."
Top middle on the panel? (Fuel Cell Reac)
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=442&start=1
Fascinating stuff :)
Ahh yes STS-93. I was in the SCA (sim control area) that morning at "O-dark hundred hours" this is a set of consoles in the MCC identical to those in the flight control room where the instructors can watch over the data in real time. Instructors have no real active role in the mission other than to provide technical support or input on how the crew may or may not react in certain situations.
I have looked at the STS-93 thread and there might be some points I can add to. Let me review my notes and the flight loop tapes and I will post something to this thread about it in a few days.
I can tell you that there were several different things all happening at once during that ascent including a small fire in the flight control room...actually an overhead projector blew out and just smoked up the room a little, but this came just after MECO when everyone had already had a much more exciting 8 1/2 minutes than planned. FLIGHT that morning was John Shannon and just after MECO I can still rember him remarking "whew...folks we don't need any more of these!!" meaning that was just like a simulation rather than the normally quiet actual launches.
The call Eileen made was a FUEL CELL PH #1...this occured as a result of the short on the ac bus which caused the fuel cell 1 to initiate a self test which in turn annunciated the PH message. The PH is just a measure of the fuel cells PH level in the water...this in itself was not directly related to the short but rather a symptom of the short. FUEL CELL PH would have sounded and alarm and the message would have shown up on the GPC CRT. When I refresh my memory I will try and post a narative of the hole sequence.
About the FUEL CELL REAC light you mentioned; thankfully no, that light did not illuminate. That light refers to the reactant valves for the fuel cells. If that lights up it is supposed to be an indication that one or more of the valves that let the hydrogen and oxygen into the fuel cells has failed closed. If this occurs and the failure is real the specific fuel cell will fail in about 30 seconds do to starvation and it will take all of the electrical busses that are connected to it down alsot...this is bad!!! Fortunately in that case you still have two more fuel cells to pick up the load...unless your day is really bad. Instructors give scenarios like this to the crews all the time, so they are prepared to react to them very quickly.
Mark Kirkman
Post by: Jamie Young on 02/21/2006 01:40 am
Post by: Launch Fan on 02/21/2006 01:48 am
Post by: Rocket Nut on 02/21/2006 10:31 am
Quote
STS Tony - 20/2/2006 8:04 PM
Seems like an awfully large amount of things to look at during flight. How long does it take to train someone to be competent in 'flying an Orbiter'? Is it the hardest 'plane' to learn?
I have to respond here...allow an old guy to reminisce for a few minutes...
I transitioned to several different aircraft over my military career. I remember vividly my first impression of every plane. It was always "wow, will I ever be comfortable with all those new instruments and switches".
After very few training sessions and before the first similator 'ride', everything seemed very familiar and "old hat". I was always amazed at just how quickly one can learn to use such a large collection of essential instrumentation once you know the basics. And the engineers work very hard at putting things in a logical place, making it even easier to become familiar with systems. Of course, they always seem to put a few circuit breakers or switches in extremely awkward places...just to keep us on our toes, I guess. After the initial training, it was just a matter of repitition, repitition, repetition, and exposure to malfunctions.
Good thing about the Shuttle is that you have a lot of other experts looking over your shoulder at all times. In a plane, it can be only one or 2 people.
Cheers,
Larry
Post by: Jonesy STS on 02/21/2006 12:41 pm
Quote
Jamie Young - 20/2/2006 8:40 PM
This place is Shuttle heaven!
Isn't it just.
I really liked the images of Mission Control. Never seen what those monitors show before.
Post by: RRP on 02/21/2006 12:57 pm
Post by: Ben E on 02/21/2006 01:33 pm
It's always amazed me, having seen in-the-cockpit liftoff videos, how violent Shuttle launches are for the astronauts and how they manage to stay focused.
Call me a wimp, but I'm not a big fan of scary rides that throw you violently upside-down, and despite any level of expertise and training on the ground or in T-38s, isn't there the risk that when an astronaut's orientation is suddenly and rapidly changed from vertical to inverted, barrelling into orbit at several thousand miles an hour, the entire cabin shaking violently, encased in a cumbersome pressure suit, trying to read and tick off a checklist attached to their knee whilst paying attention to a set of blurry computers in front of them AND preparing for a hundred different potential contingencies, isn't there a risk that they'll just momentarily lose focus and miss something?
Post by: Crispy on 02/21/2006 04:46 pm
Post by: Jim on 02/21/2006 05:43 pm
Quote
Crispy - 21/2/2006 11:46 AMMassive respect indeed for anybody who can fly one of those things. Still, the russians had the right idea with Buran - automatic takeoff and landing.
The shuttle's ascent is automatic. The crewmembers monitor the performance of the vehicle and are ready to "take over" in case of failures. "Take over" is a misnomer. The crew enacts backup procedures in case of subsystem failures and selects the abort mode (if required) but the vehicle still flys it. There has been no vehicle yet that man has piloted to orbit. The shuttle has some ability in second stage flight.
This is an outstanding issue for manrating vehicles. The guidance system still would have to provide info to the crew, the control system would have to take the crew's input and translate it into vehicle motion. All this while going to orbit with ever changing control gains. During crucial times, like liftoff, the crew can react fast enough. Addtionally, the launch vehicle must fly as close to the optimal flight path to make it to orbit. There isn't a large fuel reserve to make up for large excusions.
Post by: STS Tony on 02/21/2006 09:31 pm
Quote
mkirk - 20/2/2006 8:23 PMQuoteChris Bergin - 20/2/2006 2:45 PM
No wonders this thread jumped by 400 page views in a few hours.
Here's a question Mark, going off what we're seeing in front of us here CWF7 lights, what would Commander Collins of been seeing for her to call back on the loop, during STS-93: "This is Columbia, we're in the roll, we've got a fuel cell (glitch) level one."
Top middle on the panel? (Fuel Cell Reac)
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=442&start=1
Fascinating stuff :)
Ahh yes STS-93. I was in the SCA (sim control area) that morning at "O-dark hundred hours" this is a set of consoles in the MCC identical to those in the flight control room where the instructors can watch over the data in real time. Instructors have no real active role in the mission other than to provide technical support or input on how the crew may or may not react in certain situations.
I have looked at the STS-93 thread and there might be some points I can add to. Let me review my notes and the flight loop tapes and I will post something to this thread about it in a few days.
Mark Kirkman
That would be awesome if you could. One of the most interesting launches to learn ascent information from.
Post by: psloss on 02/21/2006 10:17 pm
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STS Tony - 21/2/2006 5:31 PMAbsolutely. STS-51F would also be interesting; I've seen/heard excerpts of film shot in the MCC during that ascent. I would love to hear the flight director loop for the STS-93 ascent, and that was before Mark's story.
That would be awesome if you could. One of the most interesting launches to learn ascent information from.
Philip Sloss
Post by: Chris Bergin on 02/21/2006 10:37 pm
Post by: Mark Max Q on 02/22/2006 05:03 pm
On lift off, some of the RCS covers at the aft blow off, but the forward RCS seem to have their covers remain on.
What is the reason for this and removes them?
Post by: DaveS on 02/22/2006 05:15 pm
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Mark Max Q - 22/2/2006 7:03 PMIt's the shockwave from the SSMEs that tears aft ones apart. As there's no significant force on the FRCS covers, they remain intact and they come off on their own a little bit later in the ascent.
Question.
On lift off, some of the RCS covers at the aft blow off, but the forward RCS seem to have their covers remain on.
What is the reason for this and removes them?
Post by: Jim on 02/22/2006 05:33 pm
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DaveS - 22/2/2006 12:15 PMQuoteMark Max Q - 22/2/2006 7:03 PMQuestion.On lift off, some of the RCS covers at the aft blow off, but the forward RCS seem to have their covers remain on.What is the reason for this and removes them?It's the shockwave from the SSMEs that tears aft ones apart. As there's no significant force on the FRCS covers, they remain intact and they come off on their own a little bit later in the ascent.
Sometimes the aft ones burn off. They are sometimes called butcher paper.
Post by: mkirk on 02/22/2006 06:41 pm
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Mark Max Q - 22/2/2006 12:03 PM
Question.
On lift off, some of the RCS covers at the aft blow off, but the forward RCS seem to have their covers remain on.
What is the reason for this and removes them?
Just t add to the other answers:
Starting with STS-114 the RCS covers were modified with a Tyvek material that has an open end or scoop. This functions as a parachute to help pull the forward RCS convers off while the shuttle is still at a relatively low velocity. This was a precaution designed to prevent the covers from coming off at a high velocity and posing a debris threat to the orbiter.
I attched a picture of the new covers but it is hard to see the opening at the top end in this photo.
Mark
Post by: Chris Bergin on 02/22/2006 08:17 pm
I know it was normal, but what was it again?
All good for when the TV people panic and need an explanation.
Post by: hyper_snyper on 02/22/2006 08:24 pm
Post by: Chris Bergin on 02/22/2006 08:26 pm
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hyper_snyper - 22/2/2006 9:24 PM
^^Birdstrike?
:) Na, covers of some sort.
Post by: hyper_snyper on 02/22/2006 08:31 pm
http://spaceflight.nasa.gov/shuttle/briefings/0726/pm/003_STS-114_EHV224_mU207143908558.jpg
Stuff that STS114 shed...
http://spaceflight.nasa.gov/shuttle/briefings/0726/pm/index.html
Post by: Chris Bergin on 02/22/2006 08:42 pm
Post by: Thomas ESA on 02/26/2006 05:25 pm
Post by: nacnud on 02/26/2006 05:40 pm
The original plan was for a two stage to orbit vehicle with both stages flying back to land on a runway. It was cheaper to go for solids and a drop tank (ET) rather than a flyback first stage. This (http://www.abo.fi/~mlindroo/SpaceLVs/Slides/sld001.htm) site has some of the cocepts that were looked at.
Post by: Jim on 02/26/2006 07:06 pm
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Thomas ESA - 26/2/2006 12:25 PMWhy did NASA go with Solids and not Liquid boosters?
High initial costs and replacement costs if they were to be lost at sea (happened on STS-4)
Post by: Rocket Guy on 02/26/2006 09:30 pm
http://www.ktb.net/~billmeco/sts114B.html
Post by: dmc6960 on 02/27/2006 07:13 pm
Post by: mkirk on 02/27/2006 07:22 pm
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dmc6960 - 27/2/2006 2:13 PM
What are some of the reasons that the Shuttle cannot be turned around and reflown as quickly as originally invisioned? Obviously thermal tile inspections take a long time, but what are some of the other reasons it cannot just be refueled and re-stacked?
I am sure the processing guys can elaborate, but I will touch on some of it.
A lot of the systems and subsystems have proven to require more TLC (tender love & care) than planned. Flight history has proven that some of them should be inspected, repleced, or serviced more often than originally planned. Another factor is access to some of these systems was not planned for in the original design phase, so it is more time consuming to get access to them. Manpower is another issue. The program can NOT afford a REAL 3 shift 24/7 operation. Yes there are three shifts but 2 of them use minimal manpower compare to day shift. Also a lot more safety oversight and quality assuranece is required than originally envisioned.
Just my thoughts, others might be able to add more.
mark
Post by: Jim on 02/27/2006 07:38 pm
Back in the days of the two week turnaround between flights, it was only going to be 2 hours after landing that the orbiter was going to be back in the OPF. Likewise, I think the countdown was 4 or 6 hours and the crew went onboard 1-2 before launch.
There were many unjustified assumptions made for the 2 weeks turnaround
Post by: nacnud on 02/27/2006 08:09 pm
Post by: Jim on 02/27/2006 08:19 pm
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nacnud - 27/2/2006 3:09 PMGiven the knowledge gained from the STS could a vehicle with a 2 week turnaround actualy be built?
DC-X did, twice in one day.
It all depends on what you want to do.
Payloads have to be designed to be ready quickly and take minimum reconfiguration. There weren't enough facilities to prepare 40 or more spacecraft, much less the nation's ability to produce that many spacecraft. It takes a month to prep a spacecraft.
The ER can't support a launch of different LV's closer than 48 hrs.
The whole space infrastructure needs to built with ops in mind.
EELV was suppose to be factory to pad. The Delta IV factory was sized for 40 boosters a year. Pad flows can't know support that rate.
Post by: nacnud on 02/27/2006 08:29 pm
Post by: mkirk on 02/28/2006 01:31 am
I found these files of Discovery on my laptop. They were taken in the OPF shortly before the STS-114 rollover to the VAB.
The FIRST PICTURE is of the aft flight deck looking into the payload bay. On the left is where the Commander/Pilot stand to fly the orbiter during rendezvous and docking. The monitor in the upper left can be used to call up the same type of flight displays as the front cockpit monitors. The controller on the left is for translational maneuvers (forward, back, up, down, left, right). The control stick in the middle of the center console is for rotational maneuvers (roll, pitch, and yaw). Above that you can see the top of a second translational controller (between the windows) that combined with another rotational controller (to the right, out of view), are used in conjunction with the controls on the right side of the console to control the RMS (remote manipulator system) or “robot arm”; they are NOT used to control the orbiter.
Notice the Canadian Flag on the RMS console.
One of our members here in the forum, Ender0319, can tell you all you want to know about operating the arm!!
On the upper left console below the window are the controls for the DAP (digital auto pilot), these allow the Commander/Pilot to select how the thrusters will fire and at what velocity and rotational rates. During the final docking phase the closure rates to the space station are very small, ideally you want to fly in at about .1 feet per second (+/- .03).
The switches on the center console around the control stick are used for controlling the video cameras and lighting in the payload bay.
The lower left and lower center console are for operating the orbiter docking system.
In the SECOND PICTURE you see a view into the payload bay thru the aft windows. You can see the red (remove before flight) cover on the top of the orbiter docking system. On the right is the robot arm. The OBSS (orbiter boom sensor system) goes on the left (no yet installed in this picture). In the back you see the top of the OMS (orbiter maneuvering system) pods and the vertical stabilizer. The speedbrake is visible in the open position.
Mark
Post by: Ender0319 on 02/28/2006 03:37 am
Post by: SimonShuttle on 02/28/2006 10:22 pm
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Ender0319 - 27/2/2006 10:37 PM
MMMMMMMMM... RMS.......
:) I bet you know every switch on that image!
Post by: Jamie Young on 02/28/2006 11:28 pm
Post by: Jim on 03/01/2006 12:29 am
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Jamie Young - 28/2/2006 6:28 PMWhy are some of the swtiched taped over?
Protect against accidental movement
Post by: Jamie Young on 03/01/2006 01:49 am
Post by: Ender0319 on 03/01/2006 02:05 am
Post by: Avron on 03/01/2006 03:25 am
Post by: mkirk on 03/01/2006 04:17 am
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Jamie Young - 28/2/2006 8:49 PM
Just those switches? The others ok to move? Ok, then this question is a bit moving on, but when that picture was taking, was Discovery turned on?
It really depends on the situation. It is a safety and shuttle configuration managment tool.
In that particular picture you can see tape on some of the switches, the tape is removed preflight and is there during processing for various reasons. If you look at the bottom right of the picture you see tape over a couple of switches that control power to the heaters in the right OMS pod. If for example a technician is doing work in that area then it is a good idea to make sure that circuit is not inadvertently activated. Other switches have metal guards such as the ones located by the control stick in the center of the console. Some switches actually have the guards over them during flight because they control very critical functions.
Another thing you might notice if you look in the middle of the left console is there are some yellow and red circuit breakers. The orbiter's circuit breakers are color coded to indicate their setting for a specific phase of flight. For example the red breakers are supposed to always be open, yellow breakers are open for ascent and then closed when the appropriate procedure says to do so, green breakers would be opened in orbit only and so on...
In general no-body is allowed to just start throwing switches while the orbiter is being processed for launch. This is true in the OPF, the VAB and on the PAD. If something needs to be adjusted all the related switch throws are coordinated thru the Test Conductors. In fact only people with specific training certification are allowed to operate the cockpit controls. This was a little hard for me to get used to the first time I entered the orbiter. I was used to climbing into the SMS (shuttle mission simulator) in Houston and doing whatever I felt was necessary such as powering on the computers, changing displays, turning up the lights, adjusting the seat, and so on. While I felt completely at home in the cockpit, at the Cape I could not touch a single thing without prior coordination and approval.
Crew members are subjected to the same treatment especially during the countdown for launch. While in the simulator a crew member wouldn't think twice about adjusting his/her seat with the electric switches on the side of the seat pan. In the real orbiter during the countdown they are supposed to check with the Launch Control Center before doing any such thing. This is because everyone in the LCC is closely analyzing every aspect of the shuttle's health and even something as simple as moving the seat can effect the orbiters electrical loads. If those folks aren't expecting you to be doing anything then they might conclude that there is some sort of electrical problem occuring deep in the system. (Actually the ground folks have gotten quite good at deciphering an unexpected cockpit change by the crew from a system's problem and they will quickly ask the crew if they changed something before assuming something is wrong with the shuttle.)
Things aren't quite so strict once the shuttle is in orbit, but even then the crew does not change the vehicles configuration on a whim. Everything is governed by written procedures and verbal communication. They are of course allowed to change the lighting or temperature or use the toilet, etc. without prior permission ;)
Here are a couple more pictures taken of Discovery at the same time as the previous ones. You will notice a lot of tape and switch guards. The first picture is the commanders side and the other is the pilots side of the cockpit.
A SIDE NOTE: If you look at the right console in the second picture of the Pilots side of the cockpit, you will see six switches with yellow tabs on the top. These are the switches that control electical power to the main engines. The two rows of switches just behind them control the helium isolation valves. To prevent the pilot from inadvertently shutting the engines off when all he intended to do was change the helium valves; someone decided that since the switches look similar they should be marked with the yellow tabs. More than one crew member in the heat of battle during a simulation has accidentally shutdown the engines...you loose a lot of "Cool Points" for that...It would be really bad to do that during a real flight.
Mark Kirkman
Post by: Avron on 03/01/2006 04:26 am
Post by: Jamie Young on 03/01/2006 04:28 am
Post by: Orbiter Obvious on 03/01/2006 04:33 am
I asked this of some engineers before and it was very nice to see how they care about the Orbiters. I don't know what it's like simply being able to go into an Shuttle Orbiter, but do they all seem different, have their own quirks? Like Columbia was the older stateswoman and Endeavour's the youngster? Just want to understand why so many people really care about these ships just like they are part of the NASA family. Maybe it's an engineer thing.
Post by: mkirk on 03/01/2006 04:43 am
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Orbiter Obvious - 28/2/2006 11:33 PM
Awesome!
Just want to understand why so many people really care about these ships just like they are part of the NASA family. Maybe it's an engineer thing.
While I am trying to get a second degree in engineering I am not technically an engineer...yet...but I can speek as a flyer and we always fall in love with our birds.
No matter what "crate" you fly or work on, it is the best flying machine ever created and the one the other guy flys or works on is piece of crap...this is true if you are talking about an F-15, a Cessna 152, a C-5, or God forbid...even a NAVY airplane;)
The thing I have noticed about being at and around NASA, compared to other places I have worked or abserved, is that everyone seems to really have a passion for what there doing that I have not seen in any other business. This carries over to the flight vehicles themselves, and while they are expensive national assets they are the focal point of your daily life and as such you start to think of them as living beings. So from what I have seen it is not just the crews and engineers, but the technicians, administrative folks, clerks, and just about anybody else you can think of.
Just my opinion.
Mark Kirkman
Post by: Shuttle Scapegoat on 03/01/2006 04:48 am
Post by: Jim on 03/01/2006 11:51 am
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Orbiter Obvious - 28/2/2006 11:33 PMAwesome!I asked this of some engineers before and it was very nice to see how they care about the Orbiters. I don't know what it's like simply being able to go into an Shuttle Orbiter, but do they all seem different, have their own quirks? Like Columbia was the older stateswoman and Endeavour's the youngster? Just want to understand why so many people really care about these ships just like they are part of the NASA family. Maybe it's an engineer thing.
I was always in the payload world, never worked on the orbiters, but worked in them and on things that flew in them.
When I was in the Air Force, we hated Columbia, she was heavy and inefficent. Only one DOD mission used her, otherwise all the others were on the newer "heavylifters". Once the DOD left the shuttle, it didn't matter and the superlightweight ET allowed Columbia to do a "DOD type" mission: AXAF.
When I worked for Boeing/Spacehab, you could tell some of the older Orbiters by how worn the paint was in the middeck and cockpit was. This was due to all the workers going in and out of the Orbiter. They were touch up, but you could see it.
Post by: SimonShuttle on 03/01/2006 12:57 pm
Post by: Ender0319 on 03/01/2006 01:34 pm
The two switches taped over on the right side of the picture belong to the A14 panel for the RMS/OMS Heaters. Those particular switches are for the Right Pod and are for system A and B.
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Ender0319 - 28/2/2006 9:05 PM
I'll have to pull out a drawing to see what the taped over switches do. I did not notice that the first time around. Good eyes!
Post by: mkirk on 03/01/2006 01:55 pm
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Ender0319 - 1/3/2006 8:34 AM
Pulled some drawings and the taped over switch on the far left of the picture is on panel A6 and belongs to the MADS (Modular Auxiliary Data System). The switch is for the "strain gage PCM ENA" which is some sort of enable switch for the pulse code modulation (PCM). I am no expert in the MADS but I do remember that is the gizmo that records instrumentation data about the orbiter and was helpful during the STS-107 investigation.
The two switches taped over on the right side of the picture belong to the A14 panel for the RMS/OMS Heaters. Those particular switches are for the Right Pod and are for system A and B.
I am embarrassed to admit that when I saw that question last night last night I didn't know what that specific switch did, so thats why I just pointed out the OMS pod heaters. Its certainly not a swithc that gets used routinely during the dynamic flight phases.
It just goes to show you how complex the shuttle is and that you never stop learning...
Mark Kirkman
Post by: mkirk on 03/01/2006 02:03 pm
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Jim - 1/3/2006 6:51 AM
When I worked for Boeing/Spacehab, you could tell some of the older Orbiters by how worn the paint was in the middeck and cockpit was. This was due to all the workers going in and out of the Orbiter. They were touch up, but you could see it.
Just to add to what Jim said: You can see a huge difference in the picture of the orbiter cockpit, even with all the covers, and the earlier pictures I posted from the simulator (around page 27 of this thread). The real cockpit from my perspective, and astronauts have said this many times, is in pristine condition compared to the simulators. The simulator is used almost all day long every day by astronauts, instructors, engineers and simulator technicians...all of this usage really shows. The most common observation is that the abort switch in the simulator is pretty much worn out...thankfully, in the real orbiter's it doesn't get used much (except during pre flight functional tests and ofcourse the one real abort to orbit on STS-51F back in the early 80's)
Mark Kirkman
Post by: Jim on 03/01/2006 02:34 pm
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mkirk - 1/3/2006 9:03 AMQuoteJim - 1/3/2006 6:51 AMWhen I worked for Boeing/Spacehab, you could tell some of the older Orbiters by how worn the paint was in the middeck and cockpit was. This was due to all the workers going in and out of the Orbiter. They were touch up, but you could see it.Just to add to what Jim said: You can see a huge difference in the picture of the orbiter cockpit, even with all the covers, and the earlier pictures I posted from the simulator (around page 27 of this thread). The real cockpit from my perspective, and astronauts have said this many times, is in pristine condition compared to the simulators. The simulator is used almost all day long every day by astronauts, instructors, engineers and simulator technicians...all of this usage really shows. The most common observation is that the abort switch in the simulator is pretty much worn out...thankfully, in the real orbiter's it doesn't get used much (except during pre flight functional tests and ofcourse the one real abort to orbit on STS-51F back in the early 80's)Mark Kirkman
Somemore to add. It is very rare to see the middeck and cockpit in flight configuration. Most of the time, all seats are removed except the CDR and PLT, all middeck lockers, all sleep stations, the airlock is empty. Depending on orientation, the floors or aft walls and WCS have GSE covers on them. Electrical and comm lines are strung through the hatch to provide power for the GSE lights and comm boxes for the workers inside. An air duct blows cool air through the hatch (just like the ones for manholes). I believe 7 is the max number of people allowed inside (10 with a Spacelab/hab attached) There is one last fixture. Anytime the Obiter is powered, there is a specialized technician onboard, the SCO (Spacecraft operator). He is the only one allowed to throw switches onboard.
Post by: British NASA on 03/01/2006 06:57 pm
Post by: rsp1202 on 03/01/2006 08:22 pm
Post by: braddock on 03/01/2006 08:27 pm
Frankly, I hope they don't go overboard, because in many ways, nothing beats a switch.
Post by: Jim on 03/01/2006 08:47 pm
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braddock - 1/3/2006 3:27 PMI'm curious to find out if the CEV is going to take the traditional 1000 switch cockpit approach, or if they will take the plunge into fully computerized glass interfaces.Frankly, I hope they don't go overboard, because in many ways, nothing beats a switch.
It will be a combination of both. There is always a need for a circuit breaker. I see glass cockpit for display and configuring non critical system. Switches and circuit breakers etc for critical systems.
Post by: mkirk on 03/01/2006 10:20 pm
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Jim - 1/3/2006 3:47 PMQuotebraddock - 1/3/2006 3:27 PMI'm curious to find out if the CEV is going to take the traditional 1000 switch cockpit approach, or if they will take the plunge into fully computerized glass interfaces.Frankly, I hope they don't go overboard, because in many ways, nothing beats a switch.
It will be a combination of both. There is always a need for a circuit breaker. I see glass cockpit for display and configuring non critical system. Switches and circuit breakers etc for critical systems.
I'll see if I can post some pictures of the "notional" cockpit layouts on the CEV thread. Basically Jim is right the multifuction displays allow a lot of flexibility but there will also be some of the traditional style knobs, breakers, and gauges.
Mark
Post by: Martin FL on 03/02/2006 12:52 am
Post by: Jim on 03/02/2006 01:03 am
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Martin FL - 1/3/2006 7:52 PMDid the RMS area get an upgrade like the flight deck area with the glass cockpit?
The mechanical attitude indicator (8-ball) (upper left) was upgraded to a flat screen display, similar to the forward cockpit. Also the CRT on the far left (out of photo) was upgraded to. So 11 total displays were added for the MEDS upgrade.
Post by: Martin FL on 03/02/2006 02:26 am
You know, I don't think I've ever been able to ask questions and get accurate answers almost immediately in seven years following the program on the internet. This is great.
Post by: Ender0319 on 03/02/2006 03:07 am
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Martin FL - 1/3/2006 7:52 PM
Did the RMS area get an upgrade like the flight deck area with the glass cockpit?
Post by: Crispy on 03/02/2006 08:44 am
Post by: Justin Space on 03/02/2006 02:23 pm
If the orbiter lost power to the computers, could she still be flown, like in the movie Space Cowboys?
Post by: mkirk on 03/02/2006 02:39 pm
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Justin Space - 2/3/2006 9:23 AM
There's a question in there somewhere!
If the orbiter lost power to the computers, could she still be flown, like in the movie Space Cowboys?
Absolutely not...No way...it is not possible!
Without the GPCs (genral purpose computers) there is no way to command thruster firings, or flight control movements, manage control system gains. There is no way to calculate and interperate data from the Inertial Measurment Units, the rate gyros, accelerameters and about a couple dozen other major problems. There would be no way for the movements of the control stick to be interpreted and acted upon by the flight control system.
Here is a simple rule of thumb, if you don't have electrons from the fuel cells, or commanding/data from the GPCs, or hydrualics from the Auxlliary Power Units...you are going to have a really bad day. That is why all of these systems have redundancy and fault tolerance built in...they are critical to flight.
I saw that movie with a bunch of my NASA freinds...they filmed it at JSC/KSC in fact a couple of my freinds were extras in it...but we all had a good laugh at the no GPC landing that they managed to walk away from.
Without the GPCs you might as well be riding in an empty soda can...they would both have about the same amount of flight control...just a useless hunk of aluminum.
Mark
Post by: Jim on 03/02/2006 02:51 pm
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Justin Space - 2/3/2006 9:23 AMThere's a question in there somewhere!If the orbiter lost power to the computers, could she still be flown, like in the movie Space Cowboys?
Never!!! The shuttle requires the computers to translate the astronauts control inputs into control surface movements (there is a lot more going on that I am leaving out). Also the shuttle is aerodynamically unstable in certain regimes and the computers keep it under control
Post by: Jonesy STS on 03/02/2006 02:58 pm
Thought that was, how does Wayne Hale say it? Undesirable, to say the least!
Post by: mkirk on 03/02/2006 03:08 pm
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Jonesy STS - 2/3/2006 9:58 AM
So much for what Clint Eastwood did in that film then. One OMS out, so a short de-orbit burn. Flips her over manually, then fires the front RCS to slow down enough for entry-interface. Then, holding on to the stick, he battles her (with TPS falling off in all directions) through re-entry.
Thought that was, how does Wayne Hale say it? Undesirable, to say the least!
Actually there is a flip procedure that is trained for extensively. So that part is actually possible. De-orbit capablity is obviously critical so there are several options such as using only a single OMS engine, crossfeeding tanks/pods, using aft RCS, aft and forward RCS, and Pre-Bank (i.e. roll the shuttle to decrease lift to get down to the atmosphere quicker and thus build up drag to slow you down).
Mark Kirkman
Post by: psloss on 03/02/2006 05:20 pm
Post by: Ben E on 03/02/2006 08:21 pm
Post by: mkirk on 03/02/2006 08:31 pm
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Ben E - 2/3/2006 3:21 PM
If the re-entry is primarily computer-controlled, do the astronauts have to worry about the old "too steep - burn up/too shallow - bounce off" problem demonstrated in the movie "Apollo 13"? Or is this exclusively governed by the computers?
If the deorbit burn goes as targeted and the orbiter is in the proper attitude then it won't be a problem. If you do anything different then yes it could be an issue.
Mark
Post by: Jim on 03/02/2006 08:38 pm
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Ben E - 2/3/2006 3:21 PMIf the re-entry is primarily computer-controlled, do the astronauts have to worry about the old "too steep - burn up/too shallow - bounce off" problem demonstrated in the movie "Apollo 13"? Or is this exclusively governed by the computers?
Duration of the deorbit burn determines the angle. Crew has some control over this (manual shut off or additional burn). Can't bounce off since any burn is going to reduce the energy to less than orbital speed (Apollo was coming from the moon faster than orbital speed). The main issue is maintaining the proper attitude and back angles to bleed off energy, yet keeping the vehicle within thermal limits. Thrusters are used early in the entry when the dynamic pressure is low. As q increases the RCS is used less and the aero surfaces more.
Hate to say it, but any loss of the critical systems mentioned earlier in the thread would result in some similar to what we have already seen.
Post by: mkirk on 03/02/2006 09:01 pm
We have basically two categories of deobit burn targets, shallow and steep. These are tradeoffs between the amount of velocity you can get rid of during the burn (i.e. Delta V) and how much you will have to loose during atmospheric flight thru aerodynamic drag. A steep trajectory is hotter but for a shorter duration...shallow targets will result in less thermally severe trajectory intitially but you are exposed to high heat for a longer duration (slowly baking the orbiter).
The burn itself can be flown in auto or manual. For auto the crew configures the propellant valves to feed from the desired tanks (straightfeed, crossfeed, etc...) checks that the burn targets are correct, arms the engines, and maneuvers the orbiter to the correct burn attitude. Burn attitude and duration will determine the entry trajectory. At T-15 seconds to the burn, they press the EXEC (execute) button on the computer keyboard. If EXEC is pressed then at T-0 the engines will fire. The burn can be stopped if needed or a "downmode" can occur if the burn needs to be completed with the RCS for example. There is a point in the burn called Safe HP (perigee altitude usually 80 to 85 nautical miles) where if you have a malfunction above this altitude then you can stop and evaluate the situation and try again later. If you are below this altitude then you are commited to re-entry and your only alternatative is to manage RCS usage, flight controls, and ROLL/PITCH attitude in an effort to control drag.
During the Burn the commander is responsible for monitoring attitude and flying manually if needed and the pilot monitors the health of the engines.
Mark Kirkman
Post by: Shuttle Scapegoat on 03/02/2006 09:23 pm
Something about them drinking salt water beforehand?
Post by: mkirk on 03/02/2006 09:34 pm
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Shuttle Scapegoat - 2/3/2006 4:23 PM
How long does it take for the orbiter to start feeling gravity after the de-orbit burn and does it make you feel really sick when you've had no gravity for a couple of weeks?
Something about them drinking salt water beforehand?
The crew does fluid loading (with a salt water solution) prior to the deorbit burn in order to reduce the effects of gravity on blood pressure and heart rate. They are supposed to drink a total of 16 ounces and 4 salt tablets in the hour before deorbit. Tastes awful!
The forces gradually start to build just after entry interface which occurs roughly 30+ minutes after the burn , they will increase to about 1.3 G and stay there for most of the entry. Crews have said that a 1/4th G after being in zero G feels like pulling two Gs in a T-38. So yes they do find it a little harder to do there job.
Mark
Post by: braddock on 03/03/2006 11:29 am
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mkirk - 2/3/2006 5:34 PM
They are supposed to drink a total of 16 ounces and 4 salt tablets in the hour before deorbit.
There must be an anticdote about that in the annals of STS history, but I'm afraid to ask.
How long from deorbit to reentry to landing?
Post by: Jim on 03/03/2006 11:36 am
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braddock - 3/3/2006 6:29 AMQuotemkirk - 2/3/2006 5:34 PMThey are supposed to drink a total of 16 ounces and 4 salt tablets in the hour before deorbit.There must be an anticdote about that in the annals of STS history, but I'm afraid to ask.How long from deorbit to reentry to landing?
There are many, especially when the shuttle gets waved off a rev and they have to fluid load again.
Post by: Hotol on 03/03/2006 12:49 pm
Post by: Ben E on 03/03/2006 02:51 pm
Post by: mkirk on 03/03/2006 06:36 pm
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Ben E - 3/3/2006 9:51 AM
It's often been said that the deorbit burn is "irreversible". At what point does it become so? If an OMS deorbit burn is terminated partway through - perhaps due to some unforeseen problem - what are the chances that the orbiter could still remain in space?
During the Deorbit burn itself the crew checks the progress of the burn by looking at a display called "DEORBIT MANEUVER EXECUTE" which shows among other things the current orbit of the shuttle and the desired orbit after the burn (the burn target). As the engines are firing the appogee altitude (highest point of the orbit) and perigee altitude (lowest point of the orbit) will change. Since the deorbit burn is retrograde, meaning the engines are firing in the direction of flight, the velocity of the orbiter is decreased and the HP (perigee altitude) will decrease.
Flight rules designate "Safe HP" as the point of no return for an orbiter during a burn. Safe HP is defined as the lowest altitude that assures a safe orbit for the shuttle for at least 24 hours. This is usually set at 80 to 85 nautical miles. The orbiter theoretically could go lower and still be considered "in orbit" but aerodynamic and orbital mechanics factors would cause the orbit to decay. So "Safe HP" is set at a value that gaurenties at least 24 hours so that trouble shooting can occur.
So if a failure occurs prior to descending below "Safe HP" then the burn will be stopped and the crew and mission control will trouble shoot and come up with a new deorbit plan. If the failure occurs after "Safe HP" then the crew will "downmode" to another configuration. Options consist of trying to continue the burn on one engine, cross feeding propellants between the OMS tanks and/or using OMS propellant for the RCS engines, using the AFT RCS jets, using the AFT RCS and then "Flipping" the orbiter to use the Forward RCS jets, rolling the orbiter to a "Pre-Bank" attitude to minimize lift and get down into the atmosphere quicker, or redesignating to another landing site.
The redesignation option is only available for Edwards landings...for instance if you couldn't slow down quick enough to make Edwards you would "RE-DES" to Northrup at White Sands New Mexico. Redesignating from a Kennedy landing is not an option since there is nothing farther down range except water.
During the burn you will hear the call "Safe HP" on the loops and PAO usually points this out because it is a major milestone.
Mark
Post by: Seattle Dave on 03/03/2006 09:14 pm
Q) Why do they keep powering up and down the Orbiters even out of OMM periods. Such as Atlantis is powered down on the latest status report. Is Atlantis completely turned off and when on, is it a case of her computer screen displays all being on etc?
Post by: Orbiter Obvious on 03/03/2006 10:00 pm
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Seattle Dave - 3/3/2006 4:14 PM
Excellent thread.
Q) Why do they keep powering up and down the Orbiters even out of OMM periods. Such as Atlantis is powered down on the latest status report. Is Atlantis completely turned off and when on, is it a case of her computer screen displays all being on etc?
Good question!!
Post by: Jim on 03/04/2006 03:10 pm
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Orbiter Obvious - 3/3/2006 5:00 PMQuoteSeattle Dave - 3/3/2006 4:14 PMExcellent thread.Q) Why do they keep powering up and down the Orbiters even out of OMM periods. Such as Atlantis is powered down on the latest status report. Is Atlantis completely turned off and when on, is it a case of her computer screen displays all being on etc?Good question!!
The orbiters are not required to powered for all the prep work. A lot of the work is mechanical: tile repair, payload attach fittings, OMS and RCS pod installlations, middeck reconfiguring. The orbiters are only powered for specifc tests: to check out systems, verify wriring and payload installations. Once it gets to pad, it is only powered up for pad verifications, payload installations, interface test, end to end tests.
Post by: Super George on 03/05/2006 06:56 pm
Will try and find it as the launch team at Kennedy were awesome in solving the problem and picked up the count at T-31 and got her off.
Post by: mkirk on 03/05/2006 07:03 pm
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Super George - 5/3/2006 1:56 PM
Are the APUs basically like big batteries? I remember seeing one launch video where they had a problem on the pad and had a specific time limit to get the launch going, with reference to how long they had left on the APUs.Quote
It's funny I just discussed the APUs for another news organization I work for.
The APUs are turbine devices fueled by hydrazine that provide the mechanical power to operate the hydraulic pumps on the orbiter. The orbiter uses hydraulic power to move the aerodynamic control surfaces (elevons, rudder, body flap etc..), gimbal the engine nozzles, operate the engine valves, retract the external tank umbilical plates, lower the landing gear, and to operate the brakes and nose wheel steering systems.
Mark Kirkman
Post by: mkirk on 03/05/2006 07:14 pm
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Super George - 5/3/2006 1:56 PM
Are the APUs basically like big batteries? I remember seeing one launch video where they had a problem on the pad and had a specific time limit to get the launch going, with reference to how long they had left on the APUs.
Will try and find it as the launch team at Kennedy were awesome in solving the problem and picked up the count at T-31 and got her off.
I think the launch you are referring to was STS-88. It was actually a launch attempt that was scrubbed because they ran out of time while discussing the issue. It was very dramatic to listen to but it actually opened a lot of eyes when it comes to dealing with problems late in the count. Mission Control in Houston and the Launch Control Team at the Cape were not on the same page when it came to evaluating the APU data for that discrepency.
At the last second as the hold time ran out KSC started to pick up the count but it was too late and Houston Flight (John Shannon) called out "we are no go for launch!!!!!!!"
I was at the Cape on NASA business not long after that and I ran into the Ascent Flight Directors (Wayne Hale, Leroy Cain, and John Shannon) in a restaurant. After exchanging pleasantries John remarked that they were in Florida to meet with the NTDs (nasa test directors)...these are the folks that manage the launch count. I replied "Oh...trying to avoid another STS-88" he rolled his eyes and said "exactly".
I tell you that only to get the point accross that many of us in the mission ops and launch ops communities were not happy with the way that went down...I think it is fair to say it scared us. You don't like to have a vehicle all powered up and loaded with fuel and not all agree that you are go for launch...and you don't want to be running around with your hair on fire trying to trouble shoot an issue.
Mark Kirkman
Post by: Chris Bergin on 03/05/2006 07:32 pm
Didn't they hold at T-31 due to the LO2 fill and drain valve showing open, rather than closed. They recycled the proceedure, while holding on the pad, a load of people crowded around a screen in the LCC, then a cheer goes up, they pick up the count and they get her off. Sound fimilar George, Mark?
Post by: mkirk on 03/05/2006 07:37 pm
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Chris Bergin - 5/3/2006 2:32 PM
I should know this stuff off by heart, but something tells me you're talking about STS-31 with Discovery - the HST launch?
Didn't they hold at T-31 due to the LO2 fill and drain valve showing open instead of closed. They recycled the proceedure, while holding on the pad, a load of people crowded around a screen in the LCC, then a cheer goes up, they pick up the count and they get her off. Sound fimilar George, Mark?
I was just trying to answer his specifc question about an APU issue. He and I may be remembering two different things. We have had many launches where we threaded the needle in trying to launch within the window. APUs are often an issue once they are started at T-5 minutes because of the limited fuel supply they have. Once they are started you need to launch quickly or scrub.
As far as an issue related specifically to the APUs themselves the most recent memory I have was the STS-88 scrub.
Mark Kirman
Post by: Chris Bergin on 03/05/2006 07:47 pm
Post by: Launch Fan on 03/05/2006 08:25 pm
Post by: mkirk on 03/05/2006 08:57 pm
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Launch Fan - 5/3/2006 3:25 PM
Interesting. How much hold time is built in before the APUs would cause a scrub?
Actully I guess I mis-spoke when I implied that the APUs have been a contraint...this is true for long launch windows but really isn't a player for the short space station launch windows of 5 to 10 minutes. The APUs are limited to 24 minutes of ground run time...so if you subtract the 5 minutes from the time they are strated during the count (T-5 minutes to T-zero) that leaves you with an APU hold time of 19 minutes. The ground run time limit ensures the APUs have enough fuel for launch and entry during the mission.
For typical launches to the space station you are limited after T-5 minutes to a hold time of the launch window itself or something we call drainback hold time. This ususally equates to about 5 ninutes or less of hold time after T-5.
Sorry for making it sound so complicated but there are a lot of variables late in the countown.
Mark Kirkman
Post by: Jim on 03/05/2006 09:33 pm
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Launch Fan - 5/3/2006 3:25 PMInteresting. How much hold time is built in before the APUs would cause a scrub?
On non-station flights, T-5 minutes was the last hold point they could stay at for any length of time.
Post by: psloss on 03/05/2006 10:52 pm
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mkirk - 5/3/2006 3:14 PMHi Mark,
I think the launch you are referring to was STS-88. It was actually a launch attempt that was scrubbed because they ran out of time while discussing the issue. It was very dramatic to listen to but it actually opened a lot of eyes when it comes to dealing with problems late in the count. Mission Control in Houston and the Launch Control Team at the Cape were not on the same page when it came to evaluating the APU data for that discrepency.
At the last second as the hold time ran out KSC started to pick up the count but it was too late and Houston Flight (John Shannon) called out "we are no go for launch!!!!!!!"
I was at the Cape on NASA business not long after that and I ran into the Ascent Flight Directors (Wayne Hale, Leroy Cain, and John Shannon) in a restaurant. After exchanging pleasantries John remarked that they were in Florida to meet with the NTDs (nasa test directors)...these are the folks that manage the launch count. I replied "Oh...trying to avoid another STS-88" he rolled his eyes and said "exactly".
I tell you that only to get the point accross that many of us in the mission ops and launch ops communities were not happy with the way that went down...I think it is fair to say it scared us. You don't like to have a vehicle all powered up and loaded with fuel and not all agree that you are go for launch...and you don't want to be running around with your hair on fire trying to trouble shoot an issue.
It's really neat to hear these stories -- I should probably just go back and look at all the launch campaigns and throw out questions. That STS-88 launch attempt was quite memorable, just listening to the main loop (channel 212), real-time.
I remember John Shannon (Houston Flight on the main loop) saying just before they ran out of time at T-31, "gotta pick it up, NTD," just after saying that they were go for launch and the ISL? console (someone help me out with the console and acronym!) "concurs," but the shuttle project engineer console (SPE, I'm a little familiar with that one) still had questions when NTD came back to them.
Listening to the inflections of the voices, even though the situation was downplayed to the press, it always sounded like there was something else going on there. To me, it sounded like there were differing senses of urgency between JSC and KSC.
The countdowns after T-9 minutes usually go so smoothly that I'm more interested in the unusual cases because they reveal more about the procedures and all the things that the teams have to deal with than when everything is nominal. That count was unusual for stopping at a couple of GLS milestones, with T-4 minutes being a little more unusual (though in the cases where they've stopped there, it's been something with the hydraulics in general or the APUs specifically).
Thanks again,
Philip Sloss
Post by: psloss on 03/05/2006 11:06 pm
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Chris Bergin - 5/3/2006 3:32 PMCoincidentally, the first launch attempt (10 April 1990) was scrubbed due to one APU (#1) that ran OK in high-speed, but not in normal speed; and they stopped at T-4 like the STS-88 attempt. The crew apparently took the APU to high-speed because it wasn't controlling the speed in normal.
I should know this stuff off by heart, but something tells me you're talking about STS-31 with Discovery - the HST launch?
Didn't they hold at T-31 due to the LO2 fill and drain valve showing open, rather than closed. They recycled the proceedure, while holding on the pad, a load of people crowded around a screen in the LCC, then a cheer goes up, they pick up the count and they get her off. Sound fimilar George, Mark?
Even though these were different issues, as with STS-88, they were going to continue down to T-31, but it sounds like just before they were going to tell the GLS console operator to pick up, the APU console comes back and says that they are no go..."the violation is LCC 6.6-6"
Philip Sloss
Post by: Maverick on 03/05/2006 11:11 pm
Post by: psloss on 03/05/2006 11:20 pm
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mkirk - 5/3/2006 4:57 PMIf I'm around soon enough before launch, I always try to keep my ears open for the LOX drainback hold time, because that does seem to me to usually be the limiter. (The last nail-biter I recall was STS-110, where I think they got off with 10-11 seconds of LOX drainback hold time left.)
For typical launches to the space station you are limited after T-5 minutes to a hold time of the launch window itself or something we call drainback hold time. This ususally equates to about 5 ninutes or less of hold time after T-5.
Perhaps you or Jim or one of the MPS folks can answer this question: for a couple of instances (pre-station) where the launch was scrubbed after holding at T-31 seconds for a long time (many minutes), the scrub has been attributed to what I've heard described as "getting outside engine start box." (One example would be the 25 Feb 1990 launch attempt for STS-36. In that case, the reason the clock was held unrelated to the engines -- a range safety computer crashed.)
If I'm not just making that up, can someone explain that, and more to the point, what's the time limit there? Is it the same thing as the LOX drainback hold time, related to LOX drainback, or something else?
Thanks,
Philip Sloss
Post by: mkirk on 03/06/2006 01:13 am
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psloss - 5/3/2006 6:20 PM
If I'm not just making that up, can someone explain that, and more to the point, what's the time limit there? Is it the same thing as the LOX drainback hold time, related to LOX drainback, or something else?
Thanks,
Philip Sloss
Although I have had to do so many times these constraints are not easy to explain quickly...I will post a summary of the launch drainback and start box limit here tomorrow. These are two differnet limits and the shorter of the two is used to determine maximum hold time between T-5 minutes and T-31 seconds.
I will probably just quote the text book on this issue...so I warn you it will not be easy reading for everyone. ;)
Mark Kirkman
Post by: psloss on 03/06/2006 01:37 am
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mkirk - 5/3/2006 9:13 PMI'm OK with that. :)
I will probably just quote the text book on this issue...so I warn you it will not be easy reading for everyone. ;)
Post by: SRBseparama on 03/06/2006 02:20 am
Post by: mkirk on 03/06/2006 02:32 am
Definitions:
Down Comer - this is the 17 in liquid oxygen feedline that runs up the lenght of the external tank.
Start Box - the engine starting temperature regime (i.e. upper and lower temperature/pressure limits for starting the engine). A graph of temperature and pressure for the start conditions would draw a box hence "start box"
Performance Margine - The external fuel tank is always filled to the 100% level for both LO2 (liquid oxygen) and LH2 (liquid hydrogen). The ET loading is not flight specific; only the MPS (main propulsion system) performance margin changes from flight to flight. The 100% level of LH2 provides more than enough fuel to complete any shuttle mission. The mission specific requirements determine how much LO2 is needed. If less than 100% of the LO2 is required for a particular mission, then that mission will have some performance margin
NOTE: The shuttle is fueled by the ground support equipment by sending the propellants from storage tanks (we will call this the ground facility) to the launch platform and into the tail service masts (TSMs). The propellant enters the orbiter from the TSM and flows thru the internal plumbing to the umbilical interface with the external tank. For the liquid oxygen, it then travels up the down comer (17 inch diameter feedline) to the liquid oxygen portion of the external tank and fills the tank from the bottom up. Once fueling is completed the ground facility contiues to replenish the oxygen and hydrogen that boils off during the count. This "stable replenish mode" continues until the last minutes of the countdown.
The attached pictures show the TSM attached to the Orbiter aft compartment, the orbiter interface with the feedline, and then a wider angle showing the 17 inch feedline that runs up the side of the tank.
DRAIN BACK HOLD TIME EXPLAINED:
After the APUs are started at T - 5:00 minutes, the LO2 outboard fill/drain valve closes at T - 4:55. No more LO2 comes in from the ground facility, but the overboard bleed valve is still open, so the LO2 in the tank "drains back" to the facility at 18 lb/sec. “Drain Back Hold Time” is defined as the time past the planned T - 0 that the launch sequence can be held during LO2 drain back until all the performance margin has drained away.
For example, 16,200 lbs of LO2 margin starts draining at approximately T - 5 minutes and takes 15 minutes to drain at 18 lbs/sec, leaving 10 minutes of drain back hold time. For this much performance margin, holding for more than 10 minutes past the planned T - 0 time would result in draining too much LO2 and not having enough to make the nominal MECO target. Drain back hold time is computed before the mission and computed in real time based on day-of ¬launch loading information from KSC. Drain back hold time is directly related to the amount of performance margin.
The LO2 in the down comer is warmer than the LO2 in the tank and is warmer than the LO2 coming from the ground facility. When drain back starts, the LO2 engine inlet temperature starts to rise as the warm LO2 from the down comer flows through the engine. When all the warm LO2 from the down comer has drained away, the LO2 engine inlet temperature starts to decrease as cold LO2 from the tank flows through the engine. If drain back continues too long, the LO2 engine inlet temperature goes below the limit for a successful engine start. When this happens, the Launch Processing System issues a launch hold. Therefore, the maximum value of drain back hold time is the length of time required to drain the LO2 down comer. For example, the amount of LO2 in the down comer is calculated by multiplying the density of LO2 by the volume of the down comer (a cylinder, 100 feet long, 17 inches in diameter). This amount of LO2 (11,186 lbs) takes approxi¬mately 10 minutes to drain at 18 1bs/sec, giving the maximum of 5 minutes of drain back hold time. If the performance margin drain back hold time is more than 5 minutes, the LO2 inlet temperature limit is violated before the performance margin limit. If the performance margin drain back hold time is less than 5 minutes, the performance margin limit is violated before the LO2 inlet temperature limit.
The smaller of these values is what determines the hold capability after T-4:55.
Another point on performance margin...during a hold the earth rotates the state of Florida and thus the Launch Pad away from the plane of the Space Stations orbit. This means a launch past the "in-plane targetd launch time" will require more gas for the shuttle to get to the correct orbit and thus each second of unplanned hold time eats up the available performance margin.
Mark Kirkman
Post by: SRBseparama on 03/06/2006 03:01 am
So basically, if the Shuttle was sat on the pad too long, with the fill and drain valve closed, the LO2 would keep boiling off to the point there wouldn't be enough LO2 to supply the SSMEs for the performance needed?
Post by: Avron on 03/06/2006 04:08 am
Post by: psloss on 03/06/2006 11:19 am
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mkirk - 5/3/2006 10:32 PMThanks, Mark. I don't know how many others would agree, but I thought that was a clear explanation, albeit of a complicated system.
Okay here is a rundown of the Drain Back Hold Time constraint that you here so much about during a shuttle count, as I warned you most of this is straight from the manual...I don't know how to say it any simpler;)
Philip Sloss
Post by: Jim on 03/06/2006 03:15 pm
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Avron - 5/3/2006 11:08 PMMark, do you have any good pics of the TSMs and their connection to the Orbiters? One question on these that the pics may be able to answer, is how do the connections get closed off at liftoff?
There is a weight that is dropped at T-0 that pulls the umbilicals off and cover slides over the opening of the TSM.
Post by: Jim on 03/06/2006 03:22 pm
http://www.spaceflight1.nasa.gov/shuttle/reference
Post by: eeergo on 03/06/2006 04:21 pm
I have a guess: are they some kind of "physical" acoustic measurers, that break apart only when the sound waves are strong enough to break them? That way, even if the throttle sensors malfunctioned, the fact that they broke or not would tell if the engines were behaving correctly... Well, maybe I'm just inventing, but I'd appreciate someone telling me what those strange circles are! (sorry if this question has been posted before and I haven't read it, but I didn't find it)
I'm attaching some pictures to illustrate what I'm asking...
Post by: mkirk on 03/06/2006 04:21 pm
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Jim - 6/3/2006 10:15 AMQuoteAvron - 5/3/2006 11:08 PMMark, do you have any good pics of the TSMs and their connection to the Orbiters? One question on these that the pics may be able to answer, is how do the connections get closed off at liftoff?
There is a weight that is dropped at T-0 that pulls the umbilicals off and cover slides over the opening of the TSM.
Here is a diagram of the TSM that shows what Jim described.
Mark Kirkman
Post by: Jim on 03/06/2006 05:17 pm
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eeergo - 6/3/2006 11:21 AMI was watching a Shuttle Launch video and for the first time I didn't look at the engines igniting. I realised that there were three "circles" that looked like paper-made, which broke when at more or less at T-4 or T-3 secs. Can anyone tell me what they are, or what are they for?I have a guess: are they some kind of "physical" acoustic measurers, that break apart only when the sound waves are strong enough to break them? That way, even if the throttle sensors malfunctioned, the fact that they broke or not would tell if the engines were behaving correctly... Well, maybe I'm just inventing, but I'd appreciate someone telling me what those strange circles are! (sorry if this question has been posted before and I haven't read it, but I didn't find it)I'm attaching some pictures to illustrate what I'm asking...
Go to page 28, it is all explained there. They are just covers for the aft RCS that burn off at liftoff
post #21732
22/2/2006 12:03 PM (#21732 - in reply to #6595)
Post by: Maverick on 03/14/2006 10:04 pm
Post by: Flightstar on 03/14/2006 10:05 pm
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Maverick - 14/3/2006 5:04 PM
When there is a delay to a launch like there is now, do they keep Discovery in her OPF for longer, or does it not matter?
For this launch it certainly does as the ET will be worked on in the transfer aisle. See story on site.
Post by: Jim on 03/15/2006 01:09 am
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Maverick - 14/3/2006 5:04 PMWhen there is a delay to a launch like there is now, do they keep Discovery in her OPF for longer, or does it not matter?
there is no where else to go.
Post by: Maverick on 03/15/2006 02:30 am
Post by: Jim on 03/15/2006 11:34 am
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Maverick - 14/3/2006 9:30 PMI thought there was two halfs to the VAB? As there's two doors? What am I missing?
There are 4 high bays (4 doors), a transfer aisle (1 door), a low bay (1 door). Shuttles are stacked in the 2 east high bays and ET's are stored in the two west ones. When there was four orbiters, one was occasionally stored on the ground level of the one of the west ones. But the orbiter is best protected by leaving it in the OPF and they can continue to work on it.
Post by: Jonesy STS on 03/16/2006 03:46 pm
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Jim - 15/3/2006 6:34 AMQuoteMaverick - 14/3/2006 9:30 PMI thought there was two halfs to the VAB? As there's two doors? What am I missing?
There are 4 high bays (4 doors), a transfer aisle (1 door), a low bay (1 door). Shuttles are stacked in the 2 east high bays and ET's are stored in the two west ones. When there was four orbiters, one was occasionally stored on the ground level of the one of the west ones. But the orbiter is best protected by leaving it in the OPF and they can continue to work on it.
I find the VAB fascinating. Did it have to undergo a lot of modication for the move from Saturns to Shuttles and will it need the same for the change from Shuttle to CEV and CaLV?
Post by: Andy L on 03/16/2006 06:21 pm
Post by: Jim on 03/16/2006 08:36 pm
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Jonesy STS - 16/3/2006 10:46 AMQuoteJim - 15/3/2006 6:34 AMI find the VAB fascinating. Did it have to undergo a lot of modication for the move from Saturns to Shuttles and will it need the same for the change from Shuttle to CEV and CaLV?QuoteMaverick - 14/3/2006 9:30 PMI thought there was two halfs to the VAB? As there's two doors? What am I missing?
There are 4 high bays (4 doors), a transfer aisle (1 door), a low bay (1 door). Shuttles are stacked in the 2 east high bays and ET's are stored in the two west ones. When there was four orbiters, one was occasionally stored on the ground level of the one of the west ones. But the orbiter is best protected by leaving it in the OPF and they can continue to work on it.
Yes, a lot. The platforms were all reconfigured, and will have to be redone for exploration
Post by: Super George on 03/16/2006 10:16 pm
Post by: Launch Fan on 03/17/2006 01:13 am
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=931&start=1
Post by: simcosmos on 03/17/2006 12:25 pm
Can we talk a little more about specific STS (Orbiter >> OMS/RCS) performance numbers (or estimatives)?
I tried to search but was not able to find too much precise info.
I mean, could someone please share what are the expected minimum / maximum values for total OMS/RCS propellant quantity in the following steps of a space shuttle mission?
1. After completing orbital insertion,
2. Before starting the final transfer burn for rendezvous (supposing here ISS),
3. At station keeping distance (before going for dock),
4. After docking,
5. Just before starting the de-orbit burn,
6. After de-orbit burn.
Related with the last point: after(?) de-orbit burn some of the remaining OMS/RCS propellant is dumped, right? How much is the minimum needed for reentry (RCS control)?
Just asking all this because, among other things, I would like to compare a few past flight tests that did with Orbiter Space Flight Simulator. Thanks to that simulator and other additional (STS) packages it is possible to almost fully simulate a shuttle mission - like in real life - with the help of automatic tools such as:
- GPC MFD (to assist, with nice graphics on the ascent, reentry, landing…)
(like seen here: http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=625&start=391 )
- STS Guidance MFD: for automatic rendezvous procedures
- Rendezvous MFD: precise approach to rendezvous
- AutoFCS: support for fully automatic deorbit burn, reentry, approach (and even landing!)
(btw: it is also possible to simulate emergency situations, while in the ascent phase)
Despite the wonderful automatic tools, I usually only use the ascent autopilot. For the rest (even for the second part of the ascent), and because in virtual world, I do it all in manual mode; on reentry I just use the DAP to keep the correct AOA; for the roll manoeuvres and everything else it is a lot more fun to do that in manual mode >> the GPC MFD gives all the required info for a precise landing.
The questions about the available OMS/RCS are being done, among other reasons, as a curiosity in order to improve my virtual flight / navigation skills. As example, from a past manual flight made without a precise preparation I arrived at ISS with:
42% on OMS/RCS (after docking),
25000Kg as payload mass,
MET = ~2 hours and 34 minutes from launch to docking
(the simulation was actually quicker >> used time acceleration during the "dead moments")
The launch window / ascent was not perfect (after orbital insertion had to correct a relative inclination of 0.5 degrees) and there were other details that could be improved.
Considering this hypothetical specific mission: would such 42% OMS/RCS quantity, at docking time, be acceptable on a real mission? I know, the payload was a "little" on the heavy side and the quick voyage time is not what is usually done: I was just doing some tests regarding high performance STS missions :)
So, if someone could please write about OMS/RCS quantities or point to where such precise data is available(?) I would greatly appreciate.
Thanks in advance,
António
Post by: Hotol on 03/18/2006 02:26 pm
Post by: Jim on 03/18/2006 02:34 pm
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simcosmos - 17/3/2006 7:25 AMHello,Can we talk a little more about specific STS (Orbiter >> OMS/RCS) performance numbers (or estimatives)?I tried to search but was not able to find too much precise info.I mean, could someone please share what are the expected minimum / maximum values for total OMS/RCS propellant quantity in the following steps of a space shuttle mission?1. After completing orbital insertion,2. Before starting the final transfer burn for rendezvous (supposing here ISS),3. At station keeping distance (before going for dock),4. After docking,5. Just before starting the de-orbit burn,6. After de-orbit burn.Related with the last point: after(?) de-orbit burn some of the remaining OMS/RCS propellant is dumped, right? How much is the minimum needed for reentry (RCS control)?Just asking all this because, among other things, I would like to compare a few past flight tests that did with Orbiter Space Flight Simulator. Thanks to that simulator and other additional (STS) packages it is possible to almost fully simulate a shuttle mission - like in real life - with the help of automatic tools such as:- GPC MFD (to assist, with nice graphics on the ascent, reentry, landing…)(like seen here: http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=625&start=391 )- STS Guidance MFD: for automatic rendezvous procedures - Rendezvous MFD: precise approach to rendezvous- AutoFCS: support for fully automatic deorbit burn, reentry, approach (and even landing!)(btw: it is also possible to simulate emergency situations, while in the ascent phase)Despite the wonderful automatic tools, I usually only use the ascent autopilot. For the rest (even for the second part of the ascent), and because in virtual world, I do it all in manual mode; on reentry I just use the DAP to keep the correct AOA; for the roll manoeuvres and everything else it is a lot more fun to do that in manual mode >> the GPC MFD gives all the required info for a precise landing.The questions about the available OMS/RCS are being done, among other reasons, as a curiosity in order to improve my virtual flight / navigation skills. As example, from a past manual flight made without a precise preparation I arrived at ISS with:42% on OMS/RCS (after docking),25000Kg as payload mass,MET = ~2 hours and 34 minutes from launch to docking(the simulation was actually quicker >> used time acceleration during the "dead moments")The launch window / ascent was not perfect (after orbital insertion had to correct a relative inclination of 0.5 degrees) and there were other details that could be improved. Considering this hypothetical specific mission: would such 42% OMS/RCS quantity, at docking time, be acceptable on a real mission? I know, the payload was a "little" on the heavy side and the quick voyage time is not what is usually done: I was just doing some tests regarding high performance STS missions :)So, if someone could please write about OMS/RCS quantities or point to where such precise data is available(?) I would greatly appreciate.Thanks in advance,António
The shuttle can barely make 55k lb to 160nmi at 28 degree. It would be a lot less for an ISS orbit.
The OMS/RCS usage would not be in open literature.
Post by: mkirk on 03/18/2006 04:01 pm
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simcosmos - 17/3/2006 7:25 AM
Hello,
Can we talk a little more about specific STS (Orbiter >> OMS/RCS) performance numbers (or estimatives)?
I tried to search but was not able to find too much precise info.
I mean, could someone please share what are the expected minimum / maximum values for total OMS/RCS propellant quantity in the following steps of a space shuttle mission?
1. After completing orbital insertion,
2. Before starting the final transfer burn for rendezvous (supposing here ISS),
3. At station keeping distance (before going for dock),
4. After docking,
5. Just before starting the de-orbit burn,
6. After de-orbit burn.
Related with the last point: after(?) de-orbit burn some of the remaining OMS/RCS propellant is dumped, right? How much is the minimum needed for reentry (RCS control)?
Here are a couple of links that will allow you to do some detective work and derive some of the numbers you are looking for. For the early shuttle flights the flight plan actually had prop usage charts in it but that is not the case. I know that the shuttle prop folks would be able to answer this and I don't hav emy notes with me so I can't answer this in the detail you want.
In taining I never really saw the big picture on prop usage from start to finish. If I were involved in Rendeavous/Docking training I would start with XX amount of prop and finish with YY. The goal was always to use as little as possible. Crew members are evaluated among other things on how well they manage prop usage during maneuvers. The basic technique is to move the stick...wait for the response and then move it again if needed. In other words give the input time to respond.
You also have to distinguish between RCS and OMS quantities. What makes this confusing is for small maneuvers less than 6 feet per second the plan is to use the RCS rather than the OMS. Also the RCS jets can use propellant from the OMS tanks but the OMS can not use RCS propellant.
With that in mind you can look at this link to the STS-114 execute packages. For instance in the FD (flight Day 2) package on page 14 you will see the expected quatities after the NC2 burn. Each package will likley have a page some where in it that mentions prop quatities before and after a set of maneuvers.
http://www1.nasa.gov/returntoflight/crew/mission_docs/execute_packages.html
This link here will give you the STS-114 Flight Plan...go down the page and select under 114 Flight Data Files the Rev A version of the Flight Plan. If you go to the attitude timeline you will see some of the Burn data and in the last column you will see on some lines a DV for Delta V in feet per second. If you know the ball park usage of RCS and OMS propellant needed for a specific delta V then you can determine propellant quatities. Example: 1% of OMS propellant is equivalent to 6 Feet Per Second, 80 LBS of oxidizer and 50 LBS of Fuel. !% of RCS Prop is equal to 1 Foot Per Second of Delta V and about 22 LBS of Propellant.
http://www.nasa.gov/centers/johnson/news/flightdatafiles/index.html
Like I said you will have to do your homework unless a Shuttle Prop Controller happens to answer this thread or until I get home in a few months and can look it up in my notes.
Post by: simcosmos on 03/19/2006 10:34 am
And talking about OMS/RCS quantities, in the current simulation, it seems that there is only a single "resource/tank" for the OMS/RCS, I mean: any burn from the reaction control system AND from the orbital manoeuvring system will drain from that unique tank. This alone might by itself lead to some improvement in performance given that there is no differentiation / constraints regarding source tanks and related management issues this to not talk about the simulation of additional things that happen in real life (that would require an immense extra work) :)
Another thing I also have to research is about propellant transfers. As far as I know / confirmed above:
- both OMS pods can crossfeed resources between them
- OMS can transfer propellant to the RCS (the other way around is not possible)
- Buran had plans for additional propellant on the cargo bay: I also seem to remember that this was at least considered somewhere on STS design phase but not implemented in the orbiter (another think that have to check)
I must now also research if the OMS >> RCS transfers are valid for all RCS thrusters, I mean: if, for example, the frontal RCS can receive from the OMS pods or if this is only valid for the rear RCS. Lots to research but little time :)
I guess that will leave all this work/googling around, etc for a later occasion (need time now for other projects). On that later occasion I might come back with a few more specific questions regarding this and hypothetical shuttle missions like, for example, the polar ones from Vandenberg (I have already saw the related threads in this forum, my questions are more about what would happen after the launch) and stuff like that.
One of the objectives of these questions is to understand a little more this incredible system's capabilities, limitations and perhaps compare those with expected performances, now that we know that STS will start its last operational period. At the same time, the space simulator and available add-ons (spacecraft, sats, tools such as MFD and automatic "computers", EVA, Virtual Mission Control, etc) give a funny and interesting way to have a small impression about how it looks like to be in a past / present STS mission and, at the same time, to have a first hint / experience about hypothetical scenarios.
Thanks again,
António
Post by: Jim on 03/19/2006 12:26 pm
The payload bay OMS tanks were not required once the shuttle program developed direct insertion.
Post by: DaveS on 03/19/2006 01:28 pm
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Jim - 19/3/2006 2:26 PMWell, I read in Jenkin's 3rd edition of his "Space Shuttle" book and it does mention a Forward RCS Interconnect System that would connect the FRCS module propellant tanks with the ARCS propellant tanks and that a test implementation of the FCIS had been done on Enterprise in the late 1990's(could be early 2000, don't have the book near me at this time).
Forward RCS can not use OMS propellant; there are no propellant lines interconnecting them.
And also noted that it had been approved for implementation.
Any truths in this?
Post by: Jim on 03/19/2006 01:53 pm
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DaveS - 19/3/2006 8:28 AMQuoteJim - 19/3/2006 2:26 PMForward RCS can not use OMS propellant; there are no propellant lines interconnecting them.Well, I read in Jenkin's 3rd edition of his "Space Shuttle" book and it does mention a Forward RCS Interconnect System that would connect the FRCS module propellant tanks with the ARCS propellant tanks and that a test implementation of the FCIS had been done on Enterprise in the late 1990's(could be early 2000, don't have the book near me at this time).And also noted that it had been approved for implementation.Any truths in this?
Never was done, one of many improvements (Electric APU's, etc) shelved
Post by: mkirk on 03/20/2006 02:57 pm
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simcosmos - 19/3/2006 5:34 AM
Another thing I also have to research is about propellant transfers. As far as I know / confirmed above:
- both OMS pods can crossfeed resources between them
- OMS can transfer propellant to the RCS (the other way around is not possible)
- Buran had plans for additional propellant on the cargo bay: I also seem to remember that this was at least considered somewhere on STS design phase but not implemented in the orbiter (another think that have to check)
Crossfeed Options:
-You can feed each OMS engine with the propellants from its own pod
-You can feed an OMS engine with one or both propellants from the other pod (oxidizer, fuel, or both)
-You can feed the AFT RCS JETS with OMS propellant from either pod.
-You can NOT feed the OMS engines with the RCS fuel tanks...it is mechanically possible if you leave the crossfeed switches in the wrong position, but you don't want to feed them this way because the OMS engines would suck the small RCS tanks dry and damage the screens that line the RCS tank walls. The screens are used to direct the fuel out of the tank in zero gravity by the use of surface tension/capillary action...this is because there are no fuel pumps and pumps wouldn't be very effective in zero g if you did have them.
-There are still switches in the orbiter cockpit for the OMS KIT but as Jim said the concept was never utilized. The OMS KIT was a pallet that would be installed in the payload bay to provide additional fuel, oxidizer, helium, and nitrogen for the OMS engines.
-The modification to add interconnect lines between the Forward and Aft RCS pods was to be incorporated...and in fact the modification got farther than most of the other shuttle modifications that were planned because it really provides alot of redundancy and flexibility...but given the short life span of the program it does not make sense to spend the money.
Post by: TheMadCap on 03/20/2006 10:14 pm
How does the Beanie Cap actually work? Is the LOX tank under pressure? If so, does the cap depress a spring clip to access the gas vent and use vacuum pumps to draw off the gas? Any close up photos of the arm in action would be wonderful.
Keep up the great work on the site!
Rick aka TheMadCap
Post by: Jim on 03/20/2006 11:20 pm
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TheMadCap - 20/3/2006 5:14 PM Greetings All! Fabulous site you have here. I have been monitoring you for quite a while and am very impressed. You seem to have some really knowledgeable personage on this site, some people who actually work at KSC and on the Shuttle itself. I can say you guys are living my dream! I am a chemist, but have always had an affinity for all things related to space ships. Took me a while to catch up on this thread, I knew the Shuttle was the complex machine ever built, but I am starting to get a much better understanding of how much is really involved in making the program happen. Anyways, I have a question: How does the Beanie Cap actually work? Is the LOX tank under pressure? If so, does the cap depress a spring clip to access the gas vent and use vacuum pumps to draw off the gas? Any close up photos of the arm in action would be wonderful. Keep up the great work on the site! Rick aka TheMadCap
The LO2 tank is not under pressure during the countdown and the vent valve is open to allow the LO2 to boil off and maintain the proper density. At T-7:30 (somebody correct me if I have the time wrong) the vent valve is closed and Beanie cap is retracted. The vent valve will maintain a pressure in the LO2 of xx psi and release GO2 if it reaches yy psi.
The Beanie cap draws off the GO2
Post by: Shuttle Man on 03/20/2006 11:48 pm
On Jim's answer. Retract Orbiter Access Arm is at T-7:30 seconds. Retract Gaseous Oxygen Vent Arm, or "beanie cap" is at T-2:55 seconds.
Post by: psloss on 03/21/2006 01:25 am
Anyway, my questions are, first, if anyone knows of documentation about the dock seal for the beanie cap...and then my second question regards the retraction of the cap and the arm...looking at launch video, it looks like the cap comes back off the nose of the ET at T-2 minutes, 30 seconds. Does the "break down" of the dock seals in the cap start at T-2 min, 55 seconds after LOX tank pressurization starts or is it between T-2:55 and T-2:30?
Thanks,
Philip Sloss
Post by: mkirk on 03/21/2006 05:10 am
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psloss - 20/3/2006 8:25 PM
I have kind of ancillary questions regarding the GOX vent hood/arm...perhaps I'm not looking in the right places, but I can't find any references to dock seals (similar, I suppose, to the white room). During the STS-1 launch campaign, I believe the seal didn't work -- at least during the FRF and launch countdowns (this is another case where I wish I could refer to the Aviation Week editions of the day). If you review video of the STS-1 launch count, on launch day, the "beanie cap" was retracted during the hold at T-9 minutes (I think), well before the normal time. I believe that was fixed by the next launch and I don't recall that happening since.
Anyway, my questions are, first, if anyone knows of documentation about the dock seal for the beanie cap...and then my second question regards the retraction of the cap and the arm...looking at launch video, it looks like the cap comes back off the nose of the ET at T-2 minutes, 30 seconds. Does the "break down" of the dock seals in the cap start at T-2 min, 55 seconds after LOX tank pressurization starts or is it between T-2:55 and T-2:30?
Thanks,
Philip Sloss
Here is the scoop as I know it:
The Gaseous Oxygen Vent Arm allows the 13 foot diameter Vent Hood (beanie cap) to drop over the top of the external tank so that heated nitrogen can be pumped in to prevent the formation of ice on the liquid oxygen tank vent louvers. Inside the hood are inflated seals that cover the lovers and direct the oxygen vapors away from the tank and out two ducts that extend downward around the midpoint of the arm. The flow rate during "boiloff" is about 1 LB per second.
For STS-1 the countdown procedure was to retract the GOX Vent Arm prior to coming out of the T-9 minute hold. It looked pretty cool to watch because even though the arm was retracted the tank continued to vent until the vent valve was closed at T-2:55. So for STS-1 you got to see the oxygen venting directly off the top of the then white external tank after T-9 minutes.
My guess is prior to STS-1 they felt that between T-9 and liftoff there would not be enough time for significant ice formation on the vent louvers. Well as most of you know that turned out not to be the case and ice debris actually damaged some tiles on the orbiter, most notably the OMS pods.
Starting with STS-2 the Arm & Hood were modified and the procedure was changed to retract the hood after the vent valve is closed for pressurization at T-2:55.
The current procedure is to start pressurization at T-2:55 and the GLS (ground launch sequencer) issues the commands to terminate the Vent Hood GN2 Purge and start the Vent Hood/Arm retract sequence at T-2:50. I guess the actual time it takes to run the sequence results in the visible movement of the hood from the tank at around T-2:30.
During the countdown while the “stable replenish” or “boil off” is underway the liquid oxygen tank ullage pressure will range from 0 to 17.1 psig. When the tank is pressurized with helium from the ground support equipment at T-2:55 it will the ullage pressure will range from 19.3 to 22.5 psig.
The picture I attached is of the Vent Arm testing conducted prior to STS-2 at the "arm farm" by the Operations and Checkout building at the Kennedy Space Center. Notice the smaller ducting than what is on the arm today. The second picture is one I took of the Vent hood prior to the 114 launch.
Post by: psloss on 03/21/2006 11:22 am
Thanks, as usual, for the details. Regarding the GOX vent hood/arm on STS-1, I was too young at the time for that to have any significance and don't remember seeing the retraction "live"; I do have some beat up copies of some Aviation Week articles made back when I was in school in the late 80s that I'll try to dig up...I don't know if they retracted the arm early for the FRF or not, but that's where I remember the issue with the dock seal being mentioned...I've since seen some video of the FRF, but also have to dig it up.
One other thing that's a bit noticeable is that the vent lines were longer, running pretty much all the way back to the FSS tower. Not sure if that was also modified between the first two flights, though sneaking a peak at a shot of STS-2 at the pad, it appears so.
Philip Sloss
Post by: astrobrian on 03/21/2006 12:24 pm
Post by: British NASA on 03/21/2006 02:17 pm
Post by: Jim on 03/21/2006 04:21 pm
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British NASA - 21/3/2006 9:17 AM About three years ago I thought the arm and beanie cap were there for stability of the stack. Shows what you can learn by reading threads like this! :)
It is only put on for the countdown. Most of the time it is retracted. I am going to diverge here a second.
For outsiders, they have a mind's eye view of the shuttle (and the oldtimers, Saturn V) of it (them) sitting at the pad in launch configuration. When in reality, it is covered by the RSS most of the time (the Saturn V was covered by the MSS). The shuttle is "exposed" only 3-4 short times during the stay at the pad. They are:
1. When it arrives at the pad
2. the RSS is retracted for payload installation
3. The day before launch
4. sometimes for APU hot fires.
Post by: Jim on 03/21/2006 04:21 pm
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British NASA - 21/3/2006 9:17 AM About three years ago I thought the arm and beanie cap were there for stability of the stack. Shows what you can learn by reading threads like this! :)
It is only put on for the countdown. Most of the time it is retracted. I am going to diverge here a second.
For outsiders, they have a mind's eye view of the shuttle (and the oldtimers, Saturn V) of it (them) sitting at the pad in launch configuration. When in reality, it is covered by the RSS most of the time (the Saturn V was covered by the MSS). The shuttle is "exposed" only 3-4 short times during the stay at the pad. They are:
1. When it arrives at the pad
2. the RSS is retracted for payload installation
3. The day before launch
4. sometimes for APU hot fires.
Post by: Jamie Young on 03/21/2006 06:11 pm
Post by: Jim on 03/21/2006 07:46 pm
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Jamie Young - 21/3/2006 1:11 PM Do they need to replace the beanie cap after each launch? I ask as it must be in a direct line of fire of the SRBs?
INo, it is retracted out of the way just like the orbiter access arm.
Post by: psloss on 03/21/2006 08:04 pm
If you're not already familiar with that, next time you see video of a shuttle liftoff from the east camera site (facing west), check it out...
Post by: TheMadCap on 03/21/2006 09:49 pm
Another dumb question:
why route the incoming cryogenic fuel and oxidizer through the shuttle into the tanks during fueling? Is it to check the flow path to ensure there are no leaks? It would seem easier to fill the tanks themselves. My apologies if I missed this in any of the previous 36 pages. :)
Post by: Jim on 03/21/2006 11:18 pm
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TheMadCap - 21/3/2006 4:49 PM Thanks for the wonderfull pics and explaination on the beanie cap. Another dumb question: why route the incoming cryogenic fuel and oxidizer through the shuttle into the tanks during fueling? Is it to check the flow path to ensure there are no leaks? It would seem easier to fill the tanks themselves. My apologies if I missed this in any of the previous 36 pages. :)
It was to save money. All the expensive fill and drain valves are on the Orbiter and get reused each flight. The ET has the minimal number of valves, the inflight disconnects, required.
Post by: Chris SF on 03/22/2006 08:35 am
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psloss - 21/3/2006 3:04 PM
Also, for a few seconds after liftoff, the vehicle drifts to the north due to the canted thrust of the main engines (one of the pros will be able to say at what point that changes...it's shortly after liftoff). Even though it doesn't take the pad tower out of the line of fire, perhaps it mitigates those effects somewhat...
If you're not already familiar with that, next time you see video of a shuttle liftoff from the east camera site (facing west), check it out...
Ah yes, I've seen the drift on the first few seconds. Always wondered about that. Thanks.
Post by: FransonUK on 03/22/2006 04:44 pm
Post by: Jim on 03/22/2006 04:48 pm
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FransonUK - 22/3/2006 11:44 AM What is the large white pole that protrudes out of the top of the launch tower?
Lightning mast
Post by: FransonUK on 03/22/2006 05:16 pm
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Jim - 22/3/2006 11:48 AMQuoteFransonUK - 22/3/2006 11:44 AM What is the large white pole that protrudes out of the top of the launch tower?Lightning mast
Damn, simply didn't 'strike' me as that obvious :)
Post by: DaveS on 03/23/2006 07:41 pm
Post by: James (Lockheed) on 03/23/2006 08:17 pm
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DaveS - 23/3/2006 2:41 PM
How long does the crew usually image the ET after jettisoning it? Just wondering.
Not sure of how long, but it's restricted from the point of having the flight deck top windows facing the falling tank to when they are out of range for filming, which is by a hand held camera I believe.
Post by: Andy L on 03/24/2006 01:12 pm
Post by: nacnud on 03/24/2006 01:25 pm
Total cost of shuttle program / number of launches = ~ $1.3B per launch
Current cost of adding a launch to the schedule* = ~$600-750M per lanch (ish)
*Not sure how this works out now the shuttle is to be retired.
Post by: Terry Rocket on 03/24/2006 02:40 pm
Post by: Jim on 03/24/2006 04:04 pm
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Terry Rocket - 24/3/2006 9:40 AM That's a lot of cash :o Any reason to how they became so expensive, as I'm sure the whole point of being a RLV was to save cash overall?
Not design for operations.
Post by: Jim on 03/24/2006 04:05 pm
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Terry Rocket - 24/3/2006 9:40 AM That's a lot of cash :o Any reason to how they became so expensive, as I'm sure the whole point of being a RLV was to save cash overall?
Not design for operations.
Post by: Davie OPF on 03/24/2006 04:40 pm
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Terry Rocket - 24/3/2006 9:40 AM
That's a lot of cash :o Any reason to how they became so expensive, as I'm sure the whole point of being a RLV was to save cash overall?
As with most new technology, it's impossible to project costs involved with maintaining and modifying. Add in the market dropping out of the primary role of the Shuttle, and the Air Force pulling out post 51L, then it all adds up.
Post by: NASA_LaRC_SP on 03/25/2006 12:15 am
Post by: Do Shuttles Dream on 03/25/2006 02:17 am
Post by: Jim on 03/25/2006 05:15 am
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Do Shuttles Dream - 24/3/2006 9:17 PMDid NASA gain any compensation from the Air Force pulling out? The money all comes from the same place, so I don't see why NASA should suffer for it?
the shuttle was forced on the Air Force . Shuttle didn't lose any funding when they left.
Post by: TheMadCap on 03/25/2006 01:50 pm
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Jim - 25/3/2006 12:15 AMQuoteDo Shuttles Dream - 24/3/2006 9:17 PMDid NASA gain any compensation from the Air Force pulling out? The money all comes from the same place, so I don't see why NASA should suffer for it?
the shuttle was forced on the Air Force . Shuttle didn't lose any funding when they left.
But is it safe to say that due to the Air Force coming on board, the shuttle's final design is radically different than originally designed? Do you think that there would be less problems with flights if one of the lighter, crew-only type crafts would have been built?
Post by: Jim on 03/25/2006 01:57 pm
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TheMadCap - 25/3/2006 8:50 AMBut is it safe to say that due to the Air Force coming on board, the shuttle's final design is radically different than originally designed? Do you think that there would be less problems with flights if one of the lighter, crew-only type crafts would have been built?
The shuttle was never crew only. The USAF requirements were 65K lbs, 60 ft long x 15 ft dia payload with 1000 mi crossrange.
NASA's was 45k and 40 ft x 10ft.
Post by: Avron on 03/25/2006 02:29 pm
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Jim - 25/3/2006 9:57 AMQuoteTheMadCap - 25/3/2006 8:50 AMBut is it safe to say that due to the Air Force coming on board, the shuttle's final design is radically different than originally designed? Do you think that there would be less problems with flights if one of the lighter, crew-only type crafts would have been built?
The shuttle was never crew only. The USAF requirements were 65K lbs, 60 ft long x 15 ft dia payload with 1000 mi crossrange.
NASA's was 45k and 40 ft x 10ft.
That is significant.. its like having a requirement for another vehicle..
Post by: mong' on 03/25/2006 03:35 pm
Granted it would have been lighter (hence less propellant) but the problems would have been the same,i.e: Thermal protection and high turnaround times.
Post by: Jim on 03/25/2006 04:29 pm
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mong' - 25/3/2006 10:35 AMyes it's a big difference but I am not sure how it could have affected the cost of the system.Granted it would have been lighter (hence less propellant) but the problems would have been the same,i.e: Thermal protection and high turnaround times.
The higher crossrange changed it from a straight wing to a delta. It also caused higher heat loads. Also a heavier return mass (both in vehicle and payload) meant higher heating rates. The TPS may have been easier to develop
Post by: mong' on 03/25/2006 04:41 pm
So if they had developed that smaller orbiter, what would it have been launched with ? a scale down version of the actual stack or more like an inline concept ? (or maybe the flyback booster ?)
Post by: Jim on 03/25/2006 05:18 pm
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mong' - 25/3/2006 11:41 AMokay so it would have made the development and operation of the heatshield easier, hence increased safety.So if they had developed that smaller orbiter, what would it have been launched with ? a scale down version of the actual stack or more like an inline concept ? (or maybe the flyback booster ?)
Flyback was the original intent. It went thru many iterations for many reasons, number 1 being to reduced development costs. There are many books on the development of the shuttle. You can't pin down one thing that caused it to be the way it is.
Post by: psloss on 03/25/2006 08:17 pm
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psloss - 21/3/2006 7:22 AM
...I don't know if they retracted the arm early for the FRF or not, but that's where I remember the issue with the dock seal being mentioned...I've since seen some video of the FRF, but also have to dig it up.
Home for a visit and dug up some video I acquired of the STS-1 FRF and the beanie cap and GOX vent arm was retracted well before T-9 minutes. Looking at some rebroadcast "Today show" video, it looks the arm was retracted by at least dawn, so perhaps it was left off the tank during tanking. Gotta see if I can find the Aviation Week reference now...
Philip Sloss
Post by: mkirk on 03/26/2006 12:27 am
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psloss - 25/3/2006 3:17 PMQuotepsloss - 21/3/2006 7:22 AM
...I don't know if they retracted the arm early for the FRF or not, but that's where I remember the issue with the dock seal being mentioned...I've since seen some video of the FRF, but also have to dig it up.
Home for a visit and dug up some video I acquired of the STS-1 FRF and the beanie cap and GOX vent arm was retracted well before T-9 minutes. Looking at some rebroadcast "Today show" video, it looks the arm was retracted by at least dawn, so perhaps it was left off the tank during tanking. Gotta see if I can find the Aviation Week reference now...
Philip Sloss
I really dont know what the procedure was for the FRF and the only people I know on the Launch Team from that period are no longer alive. My guess is that given there wasn't really any experience with fueling shuttles yet, they may have felt the vent arm wasn't necessary that late in the count or they may have taken it off early on purpose in order to quantify the formation of ice around the valve.
As for the STS-1 launch itself...although I was just a little kid I still remeber it quite clearly...and I have the tapes of the count now. The arm was retracted just prior to coming out of the T-9 minute hold. This turned out in hind sight not to be a good idea since ice did form and damage the orbiter during launch.
Post by: mkirk on 03/26/2006 12:32 am
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James (Lockheed) - 23/3/2006 3:17 PMQuoteDaveS - 23/3/2006 2:41 PM
How long does the crew usually image the ET after jettisoning it? Just wondering.
Not sure of how long, but it's restricted from the point of having the flight deck top windows facing the falling tank to when they are out of range for filming, which is by a hand held camera I believe.
There are a couple of photographic events taking palace during external tank separation. At MECO (main engine cutoff) the orbiter/ET stack is in a wings level, heads up position. About 20 seconds after MECO structural separation occurs and the orbiter automatically fires the downward thrusters in order to translate in the –Z direction (in the heads up direction) from the tank. The jets will stop firing once a separation rate of about 4 feet per second is reached. At that point the Commander flying from the left seat will push in and hold the translational controller for about 11 seconds. This is call the +X maneuver and moves the orbiter forward away from the tank by firing the reward firing thrusters. As the +X burn takes place the cameras in the orbiters ET umbilical wells will automatically photograph the tank.
The next photo event is the ET PHOTO MANEUVER. Prior to STS-114 this was more or less an optional event and was performed after the MPS DUMP (main propulsion system dump) via inputs to the control stick by the Commander. It was basically a pitch up (around) maneuver that would put the field of view of the fuel tank in the orbiter’s overhead windows. The MS1 (mission specialist 1) was usually the person with the camera and would call out to the Commander when he/she had the tank in sight. This usually involved a pitch around of 110 degrees, give or take.
After STS-107 when it was decided that ET imagery would be more critical the ET PHOTO MANEUVER was modified so that the orbiter would be closer to the tank during photography. Instead of waiting until after the MPS DUMP, the pitch around is actually a function of the dump itself. The commander places the DAP (digital auto pilot) in a mode that allows the orbiter to freely drift in pitch. As the propellants dump out the engine bells a slight propulsive (about 8 fps of Delta V) pitching moment occurs and the orbiter starts to drift around. The MS calls out to the Commander when he/she visually acquires the tank out the overhead windows and the Commander will stop the pitch movement caused by the dump thru inputs to the control system. Total pitch around is now about 125 degrees.
The crew will take pictures as long as it is useful to do so since the tank is tumbling and moving away from the orbiter. It takes just a few minutes for the entire process.
About the dump:
The MPS DUMP takes place about 2 minutes and 3 seconds after MECO. This is an automatic dump of the residual propellants trapped in the MPS feed lines after MECO. There is on average 4200 lbs of propellant that needs to be dumped overboard to prevent an AFT CG (reward center of gravity) during entry, to prevent spurious venting that could cause navigation errors or contaminate the payloads. There is also a concern that the propellant in the lines could warm and over pressurize the lines causing a rupture. The dump also prevents the trapped LH2 from combining with atmosphere during entry and creating a possibly explosive mixture.
The oxygen is forced out the engine nozzle bells by pressurized helium. The hydrogen is dumped out the LH2 Fill/Drain line on the left side of the orbiter under its own pressure (no helium). Dumping this way helps keep the propellants seperate
Post by: psloss on 03/26/2006 12:55 am
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mkirk - 25/3/2006 8:27 PMI can't find the reference, but my recollection was of a report of an issue with the dock seal. I don't have the launch day video in front of me, though I can probably find some while I'm here from both launch attempts, but I believe that the tank vented out the cap while the cap was on the tank -- rather than venting out the lines that ran away from the cap -- because the dock seal wasn't working.
As for the STS-1 launch itself...although I was just a little kid I still remeber it quite clearly...and I have the tapes of the count now. The arm was retracted just prior to coming out of the T-9 minute hold. This turned out in hind sight not to be a good idea since ice did form and damage the orbiter during launch.
Just a historical footnote -- assuming I'm not thinking of something else...on all the subsequent FRFs, the arm was retracted as with a standard count. (And perhaps even the handful of non-FRF wet countdown tests conducted.)
At any rate, I'm becoming more and more envious of some of the video and audio material you have!
Philip Sloss
Post by: TheMadCap on 03/26/2006 04:53 pm
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Jim - 25/3/2006 12:18 PMQuotemong' - 25/3/2006 11:41 AMokay so it would have made the development and operation of the heatshield easier, hence increased safety.So if they had developed that smaller orbiter, what would it have been launched with ? a scale down version of the actual stack or more like an inline concept ? (or maybe the flyback booster ?)
Flyback was the original intent. It went thru many iterations for many reasons, number 1 being to reduced development costs. There are many books on the development of the shuttle. You can't pin down one thing that caused it to be the way it is.
Remind me, was it the larger payload bay that required the shuttle be loaded on the side of the stack, or was it always planned to have it so? I thought there were early discussions about having it top loaded, a la Apollo CM, which would have eliminated the foam issue?
Post by: Jim on 03/26/2006 06:50 pm
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TheMadCap - 26/3/2006 10:53 AM
Remind me, was it the larger payload bay that required the shuttle be loaded on the side of the stack, or was it always planned to have it so? I thought there were early discussions about having it top loaded, a la Apollo CM, which would have eliminated the foam issue?
It depended on the booster they were looking at time. But payload bay size had nothing to booster mounting.
Post by: STS Tony on 03/27/2006 09:42 pm
Post by: Chris Bergin on 03/27/2006 09:46 pm
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STS Tony - 27/3/2006 9:42 PM
How did they solve the problem with the O-Ring seals after Challenger, did they simply not launch at such low temps?
The joints now have a heated layer and a third O-Ring was added, I believe (from memory).
Post by: Jim on 03/27/2006 09:57 pm
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STS Tony - 27/3/2006 3:42 PMHow did they solve the problem with the O-Ring seals after Challenger, did they simply not launch at such low temps?Also they added a "capture" tang on the segment and a "J" flap in the insulation
Post by: DaveS on 03/28/2006 12:35 pm
Post by: TheMadCap on 03/29/2006 02:53 am
Post by: Ender0319 on 03/29/2006 03:14 am
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DaveS - 28/3/2006 6:35 AM
Does anyone know the mass penalty for the orbiter carrying the OBSS? Am I right in assuming it has an mass of around 900-1200 kg?
Post by: Jim on 03/29/2006 12:41 pm
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TheMadCap - 28/3/2006 8:53 PMAfter Challenger, didn't Max Faget propose a shuttle re-design to something resembling an Energyia? I remember the proposal may have included moving the SSMEs to the ET and replacing the SRMs with liquid boosters. Is this what started the Shuttle C and Z investigations? Anyone have any specifics or further information?
The Shuttle-C configuration (like many SDLV's) go back to before the shuttle even flew. (1970's)
Post by: George CA on 03/29/2006 05:19 pm
Post by: TheMadCap on 03/29/2006 05:39 pm
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Jim - 27/3/2006 3:57 PMQuoteSTS Tony - 27/3/2006 3:42 PMHow did they solve the problem with the O-Ring seals after Challenger, did they simply not launch at such low temps?Also they added a "capture" tang on the segment and a "J" flap in the insulation
Anyone have a diagram or photo of the two types of seal systems they can post?
Post by: Jim on 03/29/2006 05:41 pm
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George CA - 29/3/2006 11:19 AMIs it right to say that the RLV design stage goes as far back as just after the start of the Saturn/Apollo era?
Yes, the early 60's
Post by: UK Shuttle Clan on 03/30/2006 01:30 pm
Post by: Jim on 03/30/2006 06:15 pm
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UK Shuttle Clan - 30/3/2006 7:30 AMSomething I've not seen a good image of is where astronauts leave the middeck into the airlock for EVA work. Is there an image of this 'hatch'?
http://spaceflight.nasa.gov/gallery/images/shuttle/sts-103/html/sts103_338_002.html
Post by: mkirk on 03/30/2006 07:57 pm
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UK Shuttle Clan - 30/3/2006 7:30 AM
Something I've not seen a good image of is where astronauts leave the middeck into the airlock for EVA work. Is there an image of this 'hatch'?
Here is another NASA pic that shows where the hatch is located in the aft mid deck...this is with the external airlock configuration that is now standard.
This was taken during egress training in one of the Mockups at the Johnson Space Center.
Mark Kirkman
Post by: DaveS on 03/30/2006 08:03 pm
What is the black stripes on the RMS end effector used for? Is it an visual indicator of some sort?
Post by: Jim on 03/30/2006 08:37 pm
Post by: Jim on 03/30/2006 08:40 pm
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DaveS - 30/3/2006 2:03 PMHere's another question I have:What is the black stripes on the RMS end effector used for? Is it an visual indicator of some sort?
yes, so they know where end is.
Post by: Chris Bergin on 04/01/2006 02:22 am
Move all questions to here:
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=2030&start=1&posts=1
Post by: newsartist on 05/01/2006 02:26 am
Even if it came apart, that seems to be a very unwieldy piece of metal to pass through the crew cabin pressure hull!
Post by: Chris Bergin on 05/01/2006 02:29 am
Please head to Shuttle Q and A (2).
Shuttle Q&A Part 2 (http://forum.nasaspaceflight.com/index.php?topic=2030)