Author Topic: External Tank Q&A  (Read 22101 times)

Offline joncz

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Offline roma847

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Re: External Tank Q&A
« Reply #21 on: 11/13/2014 09:29 am »
Thanks for the link.

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?


Source: spaceflightnow.com

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Online DaveS

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Re: External Tank Q&A
« Reply #22 on: 11/27/2014 11:28 pm »
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?
« Last Edit: 11/27/2014 11:32 pm by DaveS »
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Offline roma847

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Re: External Tank Q&A
« Reply #23 on: 11/28/2014 04:32 pm »
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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Online DaveS

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Re: External Tank Q&A
« Reply #24 on: 11/28/2014 04:50 pm »
It's the entire deal (stringer structure+foam TPS applied).
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"We're rolling in the wrong direction but for the right reasons"
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Offline roma847

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Re: External Tank Q&A
« Reply #25 on: 11/28/2014 09:50 pm »
Dave, I had asked about the difference of the diameters of the rounded insulating foam and after milling off the roundings,


Source: NASA

but 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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Online DaveS

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Re: External Tank Q&A
« Reply #26 on: 11/30/2014 12:24 am »
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.
"For Sardines, space is no problem!"
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"We're rolling in the wrong direction but for the right reasons"
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Offline DMeader

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Re: External Tank Q&A
« Reply #27 on: 12/02/2014 01:14 pm »
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.
« Last Edit: 12/02/2014 01:16 pm by DMeader »

Offline roma847

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Re: External Tank Q&A
« Reply #28 on: 12/02/2014 04:22 pm »
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.com

And these rounded shape is then milled, resulting in the final trapezoidal shape.


Source: NASA

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.

« Last Edit: 08/20/2017 06:15 am by roma847 »
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Offline Jim

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Re: External Tank Q&A
« Reply #29 on: 12/02/2014 04:45 pm »

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.
« Last Edit: 12/02/2014 04:47 pm by Jim »

Offline roma847

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Re: External Tank Q&A
« Reply #30 on: 12/02/2014 08:20 pm »
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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Online DaveS

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Re: External Tank Q&A
« Reply #31 on: 12/02/2014 08:33 pm »
According to my calculations the final diameter of the I/T with TPS applied is 334" (8.4836 m).
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Re: External Tank Q&A
« Reply #32 on: 12/02/2014 08:46 pm »
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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Re: External Tank Q&A
« Reply #33 on: 12/02/2014 11:07 pm »
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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Offline roma847

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Re: External Tank Q&A
« Reply #34 on: 12/03/2014 10:50 pm »
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.htm

And 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.

« Last Edit: 12/03/2014 10:54 pm by roma847 »
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Re: External Tank Q&A
« Reply #35 on: 12/03/2014 11:11 pm »
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.
"For Sardines, space is no problem!"
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"We're rolling in the wrong direction but for the right reasons"
-USA engineer about the rollback of Discovery prior to the STS-114 Return To Flight mission

Offline roma847

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Re: External Tank Q&A
« Reply #36 on: 12/07/2014 05:30 pm »
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.com

The 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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Offline Hog

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Re: External Tank Q&A
« Reply #37 on: 12/08/2014 02:05 pm »
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?
Paul

Offline roma847

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Re: External Tank Q&A
« Reply #38 on: 12/08/2014 03:53 pm »
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: NASA

As 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: NASA

Unfortunately I have not found a technical drawing of Intertank with milled insulation so far.

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Offline roma847

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Re: External Tank Q&A
« Reply #39 on: 12/10/2014 12:46 pm »
I still have found this drawing of the ET,


Source: www.capcomespace.net/dossiers/espace_US/shuttle/index.htm

which 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.

« Last Edit: 12/10/2014 01:41 pm by roma847 »
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Manfred

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