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External Tank Q&A
by
Mark Dave
on 07 Jan, 2012 21:56
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i'm curious on the external tank. How come the sprayed on foam is already colored as it it's been in the sun even when it's freshly built and ready to go to KSC? Are huge lamps used to sun burn the foam after the automated sprays are done?
For example this photo.
http://mafet.org/19/untitled29.html The foam is cream colored when freshly sprayed, but here it looks like it's been outside for some time to get the orange/ tan color.
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#1
by
mtakala24
on 08 Jan, 2012 00:11
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not an answer to the question, but thats a fantastic photo from the production line.
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#2
by
Phillip Clark
on 08 Jan, 2012 10:21
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Two hypotheses spring to mind. One is that the lighting where the ETs are being manufactured might simply make the olour appear to be different. The other is that some chemical reaction causes the colour to change with time.
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#3
by
Jim
on 08 Jan, 2012 12:46
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Regular lights put out UV which is what turns the color
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#4
by
Mark Dave
on 08 Jan, 2012 20:39
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#5
by
kevin-rf
on 09 Jan, 2012 12:12
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Regular lights put out UV which is what turns the color
Caveat: Regular Fluorescent Lamps that use Mercury (Almost all FL or CFL lamp you see) put out UV. 253.65 nm is an extremely strong mercury emission line.
A normal inefficient old fashion Tungsten incandescent light bulb does not produce nearly as much UV. Nor does an over priced but efficient LED lamp
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#6
by
Mark Dave
on 09 Jan, 2012 18:26
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What will become of the left over tanks at Michoud? ET-94, 139,140, and 141? The last three were ready to be flown. 94 was a test tank for the SLS.
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#7
by
mtakala24
on 09 Jan, 2012 20:57
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I was under the impression that ET-94 was used in CAIB testing, and would need very major disassembly and reassembly to certify for flight. ET-139 and subs were not ready, they were only skills retention projects and only some major subassemblies were made - not even whole LOX/LH2 tanks were completed. Did they go further with them?
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#8
by
jeff122670
on 09 Jan, 2012 23:14
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hard to believe that one "LITTLE" beam carried all of that thrust load!! WOW!
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#9
by
Fequalsma
on 12 Jan, 2012 21:04
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The beam is mostly loaded in bending thru end moments from the offset SRB forces, and doesn't see a lot of force per se. The SRB forces are mostly carried thru the Intertank's thrust panels up to the Intertank fwd ring frame/LO2 Tank barrel-aft dome joint.
F=ma
hard to believe that one "LITTLE" beam carried all of that thrust load!! WOW!
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#10
by
pagheca
on 20 Mar, 2014 20:14
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If I'm correct all 135 Space Shuttle missions deployed their ET into the Pacific or the Indian Ocean. They are valuable piece of material and technology (some of them were built in Titanium) and a very important piece of space history.
I was wondering if someone knows about any effort to locate on the seabed and/or to recover at least some of them.
Are their splashdown coordinate ever been recorded by NASA or someone else? Do they splashdown in one piece?Has any image of an ET splashdown ever been recorded? Has any of them ever been spotted by human eye after splashdown? I searched through the internet but found nothing really specific about an "Main External Tank Cemetery" somewhere, or give any other information about them after splashdown.
Actually some websites say they breakout during reentry, but I wonder if any of them ever landed in one piece.
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#11
by
Hauerg
on 20 Mar, 2014 20:17
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Since the tanks had almost orbital speed I cannot imagine big pieces coming down. Let alone a whole tank.
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#12
by
psloss
on 20 Mar, 2014 20:34
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#13
by
Chris Bergin
on 20 Mar, 2014 21:00
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#14
by
Jim
on 20 Mar, 2014 21:18
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Actually some websites say they breakout during reentry, but I wonder if any of them ever landed in one piece.
Not possible, and they were designed for breakup to prevent from being a hazard.
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#15
by
pagheca
on 20 Mar, 2014 22:48
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Not possible, and they were designed for breakup to prevent from being a hazard.
Do you mean for navigation, maybe?
That's interesting. Did you read that or maybe you were involved someway in the project?
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#16
by
Jim
on 21 Mar, 2014 00:04
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#17
by
Jim
on 21 Mar, 2014 00:06
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If I'm correct all 135 Space Shuttle missions deployed their ET into the Pacific or the Indian Ocean. They are valuable piece of material and technology (some of them were built in Titanium) and a very important piece of space history.
There are hundreds of Deltas and Atlases. Just as important. And then there are the Saturns. An ET itself is not an important piece.
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#18
by
psloss
on 21 Mar, 2014 00:27
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A bit of the 41-C footage, narrated by the flight crew pilots (mostly Dick Scobee):
http://www.airspacemag.com/videos/sts-41c-shuttle-external-tank-breakup-over-h/Probably from a post-flight presentation...by that time there was usually only one, but I haven't checked that.
There was also amateur footage from another low-inclination mission (STS-37)...but most of this is ground covered in another thread already.
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#19
by
roma847
on 12 Nov, 2014 16:45
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Does anyone know the diameter of the ET Intertank? How big is the difference of the diameter in the range of Intertank stringers and the normal diameter of the ET?
That means, how much is the diameter of the intertank stringer larger than the normal diameter?
Source: NASA
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#20
by
joncz
on 12 Nov, 2014 22:21
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#21
by
roma847
on 13 Nov, 2014 09:29
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#22
by
DaveS
on 27 Nov, 2014 23:28
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Okay, thereafter the intertank is 270 inches long and 331 inches in diameter. But the diameter of the stringer area is slightly larger, but how much? [
I believe that the actual stringer structure+TPS adds around 3-4 inches to overall diameter of the I/T.
Edit:
My ET Q is approximate dimensions of the IFRs on the LH2 tank?
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#23
by
roma847
on 28 Nov, 2014 16:32
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Tanks Dave,
does your size correlate to the diameter of the insulating foam with roundings or the diameter with milled stringers?
Since when the roundings of the insulating foam were milled?
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#24
by
DaveS
on 28 Nov, 2014 16:50
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It's the entire deal (stringer structure+foam TPS applied).
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#25
by
roma847
on 28 Nov, 2014 21:50
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Dave, I had asked about the difference of the diameters of the rounded insulating foam and after milling off the roundings,
Source: NASAbut that will not matter very much, I guess?
Remains the question of whether the roundings of the insulating foam were milled from the beginning of the Shuttle program or later?
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#26
by
DaveS
on 30 Nov, 2014 00:24
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What roundings? The stringers are essentially V-shaped with the bottom point being the flat surface you see in the photos. The legs of the V is the sides.
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#27
by
DMeader
on 02 Dec, 2014 13:14
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What roundings? The stringers are essentially V-shaped with the bottom point being the flat surface you see in the photos. The legs of the V is the sides.
More like a trapezoid (trapezium) with the wider base being against the tank.
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#28
by
roma847
on 02 Dec, 2014 16:22
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Hello guys,
let me explain briefly and show what I mean by "rounding", which may be the wrong word.
When the insulating foam is applied to the Intertank, one sees these rounded shape over the stringers.
Source: spaceflightnow.comAnd these rounded shape is then milled, resulting in the final trapezoidal shape.
Source: NASAI'm interested in the diameter of the Intertank in the final trapezoidal shape, which should be slightly greater than the diameter of the normal ET.
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#29
by
Jim
on 02 Dec, 2014 16:45
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I'm interested in the diameter of the Intertank in the final trapezoidal shape, which should be slightly greater than the diameter of the normal ET.
Probably not going to find a number because I bet it wasn't a controlled dimension.
Just need to add the foam thickness dimension to the inter tank diameter without foam.
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#30
by
roma847
on 02 Dec, 2014 20:20
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Okay Jim, but who knows the foam thickness dimension of the intertank?
Is there anybody who has technical drawings of the ET, showing these dimensions?
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#31
by
DaveS
on 02 Dec, 2014 20:33
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According to my calculations the final diameter of the I/T with TPS applied is 334" (8.4836 m).
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#32
by
Jim
on 02 Dec, 2014 20:46
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Okay Jim, but who knows the foam thickness dimension of the intertank?
Is there anybody who has technical drawings of the ET, showing these dimensions?
You can guess within a 1/4 inch. .25 out of 334 inches is less than .075%. At 100 to 1 scale, that is less than the paper thickness.
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#33
by
DaveS
on 02 Dec, 2014 23:07
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After some more careful calculations, the final OD of the I/T with TPS applied is closer to 340" (8.636 m) rather than the 334" (8.4836 m) I wrote earlier.
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#34
by
roma847
on 03 Dec, 2014 22:50
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Hi Guys,
I have found a few new things that we should consider.
In this drawing, the diameter of the ET is indicated by
331 inches, and it looks like the overall ET diameter.
Source: http://www.capcomespace.net/dossiers/espace_US/shuttle/index.htmAnd now I found this
Source in which the thickness of the insulation with
1 inch is specified.
The skin of the External Tank is covered with a thermal protection system that is a 2.5-centimeter (1-inch) thick coating of spray-on polyisocyanurate foam.This would result in a diameter of the Intertank (with milled stringer TPS) to
333 inches.
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#35
by
DaveS
on 03 Dec, 2014 23:11
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This would result in a diameter of the Intertank (with milled stringer TPS) to 333 inches.
Not quite. The I/T is larger than the rest of the ET as the attached photo shows.
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#36
by
roma847
on 07 Dec, 2014 17:30
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Okay Dave, you could be right, I've also researched again.
The diameter specified in the last drawing with 331 inches (ET OSL) is the
Outside Diameter (Outer Skin Line), i.e. without stringers and foam insulation of the intertank, which one still need to add.
Source: spaceflightnow.comThe height of the stringers I've determined from this
PDF (p. 10),
which should be approx. 2 inches, and the thickness of the insulation should be approx. 1 inch in the milled state.
Accordingly, the diameter with stringers and insulation should be approx.
337 inches.
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#37
by
Hog
on 08 Dec, 2014 14:05
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If the external diameter is 337", but that TPS foam has peaks and valleys. Aerodynamically speaking, does that slightly larger intertank portion react similarily to a smooth surface with a diameter that is the average diameter of the peaks/valleys?
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#38
by
roma847
on 08 Dec, 2014 15:53
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As you can see on most images of
External Tank, the diameter in the range of
Intertank with the stringers is slightly larger, as one can see in this image and as Dave also correctly noticed already.
Source: NASAAs specified by
NASA, the skin of the ET is covered with a
Thermal Protection System that is a 2.5-centimeter (1-inch) thick coating of spray-on foam polyisocyanurates.
I suspect that this is meant by the diameter of the milled insulation, as to be seen in this picture.
Source: NASAUnfortunately I have not found a technical drawing of Intertank with milled insulation so far.
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#39
by
roma847
on 10 Dec, 2014 12:46
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I still have found this drawing of the ET,
Source: www.capcomespace.net/dossiers/espace_US/shuttle/index.htmwhich is one part of a NASA Collection
"ET Inboard/Outboard Profile (Sheet 1 of 7)" in the green frame. It includes a series of cross sections (red frames) A-A, B-B, C-C, ... S-S, that would surely help with more details, especially the sections
A-A and
B-B (SH 2) of the Intertank.
Unfortunately I have only therefrom sections G-G and K-K (SH 1).
Who knows or has these drawings with the other cross sections or knows the source where this sheet collection is to be found?
Thanks in advance.
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#40
by
DaveS
on 10 Dec, 2014 13:22
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#41
by
roma847
on 10 Dec, 2014 22:48
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Thanks David for the reminder,
this thread of course I know.
In volume 2 of the handbook I've found all the ET layout drawings, really great stuff for scratch building.
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#42
by
ZachS09
on 12 Dec, 2014 14:49
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Did you know that if ET-94, 139, 140, and 141 were all put to flight-readiness, the Space Shuttle program could last for four more missions until maybe the end of 2013? I'm saying until the missions equal 139. That is a hypothetical statement, but could have been possible if NASA paid more funds.
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#43
by
Jim
on 12 Dec, 2014 15:23
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Did you know that if ET-94, 139, 140, and 141 were all put to flight-readiness, the Space Shuttle program could last for four more missions until maybe the end of 2013? I'm saying until the missions equal 139. That is a hypothetical statement, but could have been possible if NASA paid more funds.
Not true, because there were many other items that would be needed for those flights that had contracts ended.
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#44
by
roma847
on 12 Dec, 2014 16:01
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Nevertheless, it would have been nice.
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#45
by
ZachS09
on 12 Dec, 2014 20:31
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What else would NASA need to keep the shuttles flying besides funds and all that government stuff?
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#46
by
wolfpack
on 12 Dec, 2014 21:00
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What else would NASA need to keep the shuttles flying besides funds and all that government stuff?
Probably should ask that in the Shuttle Q&A thread, but the horse left the barn in 2008 really. That's the last time parts suppliers were ordered from. The logistics chain for STS was dead after that. It was flying on what was left on NASA's shelves.
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#47
by
mtakala24
on 12 Dec, 2014 21:14
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Also, all the toxic systems (APU, RCS) were dismantled/scrapped, and all thats left on the shuttles now are just cleaned-up visible parts.
There also the environmental issues; there were numerous systems and processes that only had waivers to be used until the end of the program.
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#48
by
roma847
on 16 May, 2020 16:43
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Is there anybody who has a source with the dimensions of the
LH2/LO2 Cable Trays (width/height), or still better original drawings?
Thanks.
