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#3660 by Hog on 05 Jun, 2020 15:35
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Way upthread, I was making the same discussion about SSME in Position 2 and 3(left and right engine positions). And while having engine 2 and 3's nozzles splayed further apart for the "start" position was perhaps a small part of the reason, primarily the start position was to control thrust vector in an attempt to reduce of center loading of the stack. An effect was a reduced "twang" effect which at the same time reduced that amount of movement in the SRB joints. The SRB joints elusively allow for the "twang" movement as the SRB nozzles are bolted hard-down to the MLP .Been watching close-up/high speed imagery of SSME and SRB launch events on NASA TV. Always wondered why the SSME nozzles pulled toward each other (while at full thrust) just before SRB ignition. Final check of engine controller? Final check of gimbaling? Thanks!
That is the RS-25s moving to actual launch position--they are slightly splayed as they spin up to full thrust to avoid hitting each other during start-up transients. (that is, to keep the nozzles from hitting each other--that would make for a very bad day)
EDIT: not sure which imagery you've been watching, but I've seen super high res/super slo-mo imagery where one can see not just the large-scale transients (engines shaking visibly), but also the harmonics in the nozzles themselves--subtle oscillations much like a ringing bell. Amazing stuff!
A quote from JIM discussing flight and start SSME positions.
http://forum.nasaspaceflight.com/index.php?topic=2030.525
"They are spaced apart to allow for motion during the start transient. They might bang together if they were in the flight position."
From M Kirkman reply 3160 of this thread
https://forum.nasaspaceflight.com/index.php?topic=17437.3160
"While it is true that keeping the engine bells from colliding is an important consideration, the “start position” (as it was explained to me) is really about loads management of the entire stack (i.e. twang) during the thrust buildup. The other day I just happened to have a discussion over lunch about thrust buildup with some of the folks involved in evaluating/quantifying the “Twang” pre and post STS-1. As it turns out, the timing of those events did not go quite as expected or planned for STS-1.
Mark Kirkman"
Twang motion at the External Tank top end, where the Gaseous Oxygen beanie cap resides before launch.
The twang motion continues on for quite some time follow the conclusion of a Flight Readiness Firing(FRF) and/or a Redundant Set Launcher Sequencer(RSLS) Aborts. RSLS aborts occur after the engine start command given at T minus 6.6 seconds but before the redundant frangible nuts and SRB ignition firing chain is triggered at T Zero. These were the worst cases of "Launchus Interuptus". The astros feel the engines startup and running, but fail to feel the 2 SRBs fire off. This is followed by the astronauts keenly listening for what type of egress is needed. Hoping to not hear Mode-1, which means pop your belts and get out of the orbiter as quickly as possible and getting to the slidewire gaskets.
This video of STS-68 RSLS Launch Pad Abort OTV Camera 071 shows the startup sequence with engines 2 and 3 in the start position then following start they immediately slew together into the "launch" position then immediatley splay apart once again as an RSLS abort was commanded.
Nozzle "bending" during startup. The flow separation and other dynamics within the engine nozzle is fascinating.
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#3661 by cebri on 09 Jun, 2020 12:11
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Now that the discussion is focused on the SSME, I do have one question. I read sometime ago, can't remember where, that the in the early days of the space shuttle, the turbo pumps came back is such bad conditions after each flight that sometimes they could not be dismounted for refurbishment and they actually needed to be literally sawed from the rest of the engine. Is there any truth to this?
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#3662 by DaveS on 20 Jun, 2020 17:05
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Any orbiter C&T techs or engineers around? If so, maybe you could help me out with the attached wire diagram? It is of the Ku band reflector horn. On the main structure there's a rectangular box with 4 connectors/wires coming out of it and I want to know how they connect with the main cube that also have 4 connectors on it. The connectors on the "box" have the prefix of "E" and the ones on the horn cube have the prefix of "H". I want to know how each connects like E1 connects with H3 for example.
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#3663 by mkirk on 28 Jun, 2020 14:17
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Space Shuttle Training Briefings
Throughout this Space Shuttle Q&A Thread/Forum, the subject of shuttle aborts has come up numerous times. Since before STS-1 even flew, there were (and still are) countless myths regarding how the shuttle was actually flown/operated, and how it would have been flown in various nominal, off-nominal, and contingency abort scenarios - particularly with regard to expected survivability.
The links below are to some recently produced Briefing on the topic of Shuttle Ascent / Abort procedures and techniques. They are presented by Andy Foster, a former Space Shuttle Training Instructor in the same group that I would ultimately end up working in for a while. He presents these briefings in essentially the same fashion as we presented the initial academics to Astronauts before beginning their Shuttle Mission Simulator (SMS) training.
Andy is still conducting the remaining briefings every Tuesday night via the Webex Meeting app at 7:00 central time. You can still sign up for free to participate in the remaining briefings by sending an email to: [email protected]
The remaining briefs will cover Contingency Aborts - by far the most complex and “scariest” aspects of shuttle flight operations. Can the space shuttle ditch in the ocean? When and how would the crew bailout? What if all 3 engines fail during first or second stage?
Once those are recorded I will update this post with links to them as well.
Space Shuttle Ascent Overview:
Space Shuttle Ascent Aborts - Return to Launch Site (RTLS):
Space Shuttle Ascent Aborts - Transoceanic Abort Landing (TAL):
Space Shuttle Contingency Aborts Part 1:
Space Shuttle Contingency Aborts Part 2:
Here is a link to a Space Shuttle Ascent briefing Andy presented to the news media prior to the first flight (STS-26) after the Challenger Accident :
Mark Kirkman
“NASA Space Shuttle Hugger” -
#3664 by DaveS on 06 Jul, 2020 23:20
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Does anyone know the angle of the PLB flood-lights WRT horizontal? From my observations, the look to be pointed approx. 40° upwards, is this correct?
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#3665 by Hog on 11 Jul, 2020 12:32
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Space Shuttle Training Briefings
Throughout this Space Shuttle Q&A Thread/Forum, the subject of shuttle aborts has come up numerous times. Since before STS-1 even flew, there were (and still are) countless myths regarding how the shuttle was actually flown/operated, and how it would have been flown in various nominal, off-nominal, and contingency abort scenarios - particularly with regard to expected survivability.
The links below are to some recently produced Briefing on the topic of Shuttle Ascent / Abort procedures and techniques. They are presented by Andy Foster, a former Space Shuttle Training Instructor in the same group that I would ultimately end up working in for a while. He presents these briefings in essentially the same fashion as we presented the initial academics to Astronauts before beginning their Shuttle Mission Simulator (SMS) training.
Andy is still conducting the remaining briefings every Tuesday night via the Webex Meeting app at 7:00 central time. You can still sign up for free to participate in the remaining briefings by sending an email to: [email protected]
The remaining briefs will cover Contingency Aborts - by far the most complex and “scariest” aspects of shuttle flight operations. Can the space shuttle ditch in the ocean? When and how would the crew bailout? What if all 3 engines fail during first or second stage?
Once those are recorded I will update this post with links to them as well.
Space Shuttle Ascent Aborts - Return to Launch Site (RTLS):
Space Shuttle Ascent Aborts - Transoceanic Abort Landing (TAL):
Space Shuttle Contingency Aborts Part 1:
Space Shuttle Contingency Aborts Part 2:
Here is a link to a Space Shuttle Ascent briefing Andy presented to the news media prior to the first flight (STS-26) after the Challenger Accident :
Mark Kirkman
“NASA Space Shuttle Hugger”
I am a user who reads all NSF posts via the "Unread Posts" menu. As such I was NOT que'd into M Kirks addition of the newest of Andy Fosters Abort talks. I am giving his post a BUMP as the Contingency Aborts talk is now up.
Thank you to all involved. I've got some video to peruse.
Paul S-alphabet-horn
"NASA Space Shuttle Hugger" -
#3666 by mkirk on 02 Aug, 2020 02:07
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Hey Folks-
Some fellow SMS (Shuttle Mission Simulator) Instructors posted some videos of an Integrated Sim for STS-135 in another group forum. They said I could link those videos here as well.
This Integrated Simulation was conducted on 6/16/2011 for STS-135.
What you will see is a video for each of the 4 runs they conducted this particular day. The video shows 4 cameras that usually monitored the PFD (primary flight display) in the shuttle simulator cockpit, another camera showing a PASS (primary) GPC (general purpose computer) display, a third showing a BFS (backup flight system) display, and a 4th that is usually looking out the commander’s side window. All of the audio is from within the cockpit as Chris Ferguson, Doug Hurley, Sandra Magnus, and Rex Walheim work through the problems and talk to CAPCOM Butch Wilmore.
I will also post a pdf link at the very bottom to the Sim Instructor Script used that day. You will notice that it mentions 5 runs, but iirc, only 4 were done that day.
FYI; the PFD shows, (from left to right), MACH/VELOCITY, ANGLE OF ATTACH (ALPHA), the attitude of the shuttle with regard to the earth horizon, ALTITUDE (in thousands of feet) and rate of climb (H-dot in feet per second).
Unfortunately the cameras used for this cutoff the tops of each display - what you would normally see up on the top would be the GPC Modes, Display Title, and Mission Elapsed Time.
VIDEO 1
Is from Run #1 of the script, a “TAL - Cabin Leak” scenario:
VIDEO 2
Is from Run #4 of the script; a “ATO - Launch hold, BFS engage for GPC failures” scenario:
VIDEO 3
Is from Run #2 of the script; a “Stuck droop - 1 engine throttle stuck and 1 engine shutdown” scenario:
VIDEO 4
Is from Run #3 of the script; a “Systems AOA - loss of 2 H2O loops” scenario:
Here’s a link to a pdf of the Sim Script
https://ia601400.us.archive.org/16/items/sts-135-ascent-3/STS-135%20Ascent%203.pdf
Mark Kirkman
“NASA Space Shuttle Hugger”
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#3667 by psloss on 02 Aug, 2020 13:32
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Some fellow SMS (Shuttle Mission Simulator) Instructors posted some videos of an Integrated Sim for STS-135 in another group forum. They said I could link those videos here as well.
Nice. Thanks, Mark.
This Integrated Simulation was conducted on 6/16/2011 for STS-135.
This is the ascent simulation day that media was invited to watch from Building 5 and then Building 30. It is interesting to see some of the displays, but especially to hear the crew intercom. On the day, the flight director loop was available.
Are there any Booster-FIDO sim runs out there?
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#3668 by Gingin on 05 Aug, 2020 08:45
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That are some incredible footages, and deeply interesting scenarios and pdf
The AOA for H2O loop failure is very interesting, especially with the Systems AOA procedures FDF that we can find on L2 section.
Thanks for the highlight.
Can we share those videos or is it just for forum members?
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#3669 by mkirk on 06 Aug, 2020 22:04
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Thanks for the highlight.
Can we share those videos or is it just for forum members?
Yes, you can share.
Mark Kirkman -
#3670 by mkirk on 06 Aug, 2020 22:27
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Here is another set of videos - this time from an Integrated Entry Sim for STS-135 on Jun 15, 2011
Once again the screen montage seems somewhat random, but typically it consists of a PASS (primary system) GPC, a BFS (backup flight system) GPC, an out the window view, and a PFD (primary flight display).
I will include a link to a pdf of the Simulation Script used by the Instructor Team at the bottom of this post.
The PFD screen shot depicts (from left to right) MACH/Relative Velocity in thousands of feet per second (knots equivalent airspeed is in the box at the bottom of the tape, ALPHA (angle of attack), orbiter attitude with respect to the horizon, H (altitude in nautical miles until below 65 nm, then it is altitude in thousands of feet), H Dot (is vertical velocity in feet per second).
VIDEO 1
Begins about 28 minutes prior to the Deorbit Burn and runs through landing
https://m.youtube.com/watch?feature=youtu.be&v=FYdkVLeo-1Y
VIDEO 2
Labeled ENTRY 3 - Begins when the orbiter has descended through 200,000 feet
https://m.youtube.com/watch?feature=youtu.be&v=DRczw5lG29A
VIDEO 3
Labeled ENTRY 4 - Begins when the orbiter has descended through 200,000 feet
VIDEO 4
Labeled ENTRY 5 - Begins when the orbiter has descended through 200,000 feet
Pdf of the STS-135 Integrated Entry #2 Simulation Script:
https://ia801401.us.archive.org/4/items/sts-135-entry-2/STS-135%20Entry%202.pdf
Mark Kirkman
“NASA Space Shuttle Hugger”
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#3671 by Gingin on 07 Aug, 2020 10:08
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Yes, you can share.
Mark Kirkman
Perfect.
Last one is very interesting also.
Thanks for sharing those stuffs
So entertaining when you spent hours reading SCOM etc
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#3672 by penguin44 on 09 Aug, 2020 04:52
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Sitting here reading a bit about sts-48. Amazing work, but I was wondering why the need for a 3 person Eva? Would it not have been better to spin Endeavour to match the sat and then just use the rms?
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#3673 by Fequalsma on 09 Aug, 2020 22:55
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I think you mean STS-49. The 3-crew EVA was done because they were DESPERATE for a solution, as the capture bar approach was a complete non-starter.
Think about what you're proposing to do. Let's just spin up the WHOLE orbiter to # RPM, and then grab Intelsat with the RMS. Probably rip the dam thing right off the Orbiter.
F=maSitting here reading a bit about sts-48. Amazing work, but I was wondering why the need for a 3 person Eva? Would it not have been better to spin Endeavour to match the sat and then just use the rms?
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#3674 by Jorge on 10 Aug, 2020 01:55
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I think you mean STS-49. The 3-crew EVA was done because they were DESPERATE for a solution, as the capture bar approach was a complete non-starter.
Think about what you're proposing to do. Let's just spin up the WHOLE orbiter to # RPM, and then grab Intelsat with the RMS. Probably rip the dam thing right off the Orbiter.
F=maSitting here reading a bit about sts-48. Amazing work, but I was wondering why the need for a 3 person Eva? Would it not have been better to spin Endeavour to match the sat and then just use the rms?
Agreed, STS-49. Intelsat was spin-stabilized and there was quite a bit of analysis between the second and third rendezvous attempts as to exactly what the spin rate should be, to strike the best compromise between stability (minimize "coning" motion) and ability of the EVA crewmen to grab the spinning Intelsat. The "knee" in the curve for Intelsat, as it turned out, was 0.25 RPM (1.5 deg/s).
A matched-rate flyaround with Endeavour wouldn't have literally ripped the RMS off, but the in-flight experience of STS-87 showed that 2 deg/s was definitely not doable, and STS-87 post-flight investigation showed that the realistic upper limit was around 0.5 deg/s, assuming the target satellite rotation was *stable*... Intelsat definitely wouldn't have been stable at 0.5 deg/s. But assuming you could match rates, then what? As Fequalsma says, the capture bar *simply didn't work*. "...then just use the RMS" is a ridiculous answer... what, exactly, does the RMS grapple onto if the capture bar doesn't work?
Source: me. I worked both missions. -
#3675 by Fequalsma on 10 Aug, 2020 22:34
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Good additional information, Jorge. A colleague supported another experiment on STS-49, and told me about the Intelsat simulator used to practice the capture in the WETF. Apparently the capture bar worked perfectly in the pool.
F=ma -
#3676 by gosha_space on 17 Aug, 2020 01:57
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Hey Folks-
Some fellow SMS (Shuttle Mission Simulator) Instructors posted some videos of an Integrated Sim for STS-135 in another group forum. They said I could link those videos here as well.
This Integrated Simulation was conducted on 6/16/2011 for STS-135.
What you will see is a video for each of the 4 runs they conducted this particular day. The video shows 4 cameras that usually monitored the PFD (primary flight display) in the shuttle simulator cockpit, another camera showing a PASS (primary) GPC (general purpose computer) display, a third showing a BFS (backup flight system) display, and a 4th that is usually looking out the commander’s side window. All of the audio is from within the cockpit as Chris Ferguson, Doug Hurley, Sandra Magnus, and Rex Walheim work through the problems and talk to CAPCOM Butch Wilmore.
I will also post a pdf link at the very bottom to the Sim Instructor Script used that day. You will notice that it mentions 5 runs, but iirc, only 4 were done that day.
FYI; the PFD shows, (from left to right), MACH/VELOCITY, ANGLE OF ATTACH (ALPHA), the attitude of the shuttle with regard to the earth horizon, ALTITUDE (in thousands of feet) and rate of climb (H-dot in feet per second).
Unfortunately the cameras used for this cutoff the tops of each display - what you would normally see up on the top would be the GPC Modes, Display Title, and Mission Elapsed Time.
VIDEO 1
Is from Run #1 of the script, a “TAL - Cabin Leak” scenario:
VIDEO 2
Is from Run #4 of the script; a “ATO - Launch hold, BFS engage for GPC failures” scenario:
VIDEO 3
Is from Run #2 of the script; a “Stuck droop - 1 engine throttle stuck and 1 engine shutdown” scenario:
VIDEO 4
Is from Run #3 of the script; a “Systems AOA - loss of 2 H2O loops” scenario:
Here’s a link to a pdf of the Sim Script
https://ia601400.us.archive.org/16/items/sts-135-ascent-3/STS-135%20Ascent%203.pdf
Mark Kirkman
“NASA Space Shuttle Hugger”
This is the most unique material! Thank you so much! I am currently practicing a shuttle landing and noticed that the motion model + atmosphere model is not correct thanks to your videos.
How accurate are the mathematical motion models used in this simulator?
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#3677 by Fequalsma on 17 Aug, 2020 02:18
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One would hope 100% accurate. Wouldn't be worth much if they weren't.
F=maHow accurate are the mathematical motion models used in this simulator?
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#3678 by gosha_space on 17 Aug, 2020 04:26
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An error occurs when trying to load a display format GPC MEMORY. What to do? What is the reason?
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#3679 by Jorge on 17 Aug, 2020 05:37
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An error occurs when trying to load a display format GPC MEMORY. What to do? What is the reason?
The MDU lost comm with the IDP via the 1553 bus.
If this were on a real shuttle or a flight-realistic simulator, I'd suggest working MAL PROC DPS 5.6d, 'BIG ‘X’ ACROSS MDU AND/OR
‘POLL FAIL’, p 5-47. I think the answers to blocks 1-3 are NO so you can start in block 10 on p 5-48.
https://www.nasa.gov/centers/johnson/pdf/359891main_125_MAL_G_J_2_E1.pdf
Since I have no idea what fidelity the sim you're running is, I have no idea if this procedure will work.
