Author Topic: IUS Q&A  (Read 7937 times)

Online DaveS

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IUS Q&A
« on: 03/26/2010 06:11 PM »
I have a IUS question. I know that the IUS second stage came in two versions, one with a normal nozzle and one with an extendable exit cone. Which one of these were the most used one?
« Last Edit: 09/02/2014 04:11 PM by DaveS »
"For Sardines, space is no problem!"
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Offline Jim

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Re: IUS Question
« Reply #1 on: 03/27/2010 12:00 PM »
Only extendable.

Online DaveS

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Re: IUS Question
« Reply #2 on: 03/27/2010 12:24 PM »
Only extendable.
Thanks. Also another few questions:

1: On SRM-1, a exit cone cover was installed on it prelaunch. What was the purpose of this cover?
2: Did SRM-2 nozzle have any thermal cover on it like the SRM-1 nozzle?
3: Was there any cover over the top of  the ESS?
"For Sardines, space is no problem!"
-1996 Astronaut class slogan

"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 Jim

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Re: IUS Question
« Reply #3 on: 03/27/2010 01:07 PM »
1.  Not to have stuff float up into it.  Also for thermal reasons.
2.  Don't remember
3.  depended on the spacecraft adapter.

Online DaveS

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Re: IUS Q&A
« Reply #4 on: 09/02/2014 04:10 PM »
Another set of Qs on the IUS:

1: What was the length of the interstage structure?
2: Extension time of the SRM-2 EEC?
3: Specific impulse and thrust of the REM thrusters?
« Last Edit: 09/02/2014 04:11 PM by DaveS »
"For Sardines, space is no problem!"
-1996 Astronaut class slogan

"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 edkyle99

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Re: IUS Q&A
« Reply #5 on: 09/05/2014 05:26 PM »
Another set of Qs on the IUS:

1: What was the length of the interstage structure?
I'm still digging for this number.  It is surprisingly hard to find.
Quote
2: Extension time of the SRM-2 EEC?
17 seconds, according to an old user manual.  It took place immediately after staging.  The Stage 2 burn did not start until about 2 minutes later.
Quote
3: Specific impulse and thrust of the REM thrusters?
I haven't found a listing, but I did find that the post Stage 2 vernier burn lasted 6 m 40 sec and used 94.5 pounds of propellant (using multiple REM thrusters).  The thrusters used hydrazine (N2H4) mono-propellant.  Typical ISP for such thrusters is 220-230 seconds, give or take.  I found one mention of Kaiser-Marquardt as the thruster manufacturer, but no details.

 - Ed Kyle
« Last Edit: 09/06/2014 07:39 PM by edkyle99 »

Offline Jim

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Re: IUS Q&A
« Reply #6 on: 09/05/2014 05:50 PM »
I haven't found a listing, but I did find that the post Stage 2 vernier burn lasted 6 m 40 sec and used 94.5 pounds of propellant (using multiple REM thrusters).  The thrusters used hydrazine (N2H4) mono-propellant.

I found it interesting the motors were undersized to make sure that there was no over burn and the vernier burn made up for the intended shortfall and any additional shortfall.  If there was a hot motor then the vernier burn was much shorter.

Offline edkyle99

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Re: IUS Q&A
« Reply #7 on: 09/05/2014 06:04 PM »
I haven't found a listing, but I did find that the post Stage 2 vernier burn lasted 6 m 40 sec and used 94.5 pounds of propellant (using multiple REM thrusters).  The thrusters used hydrazine (N2H4) mono-propellant.

I found it interesting the motors were undersized to make sure that there was no over burn and the vernier burn made up for the intended shortfall and any additional shortfall.  If there was a hot motor then the vernier burn was much shorter.
I suppose that injection accuracy was extra critical for direct to GEO missions (compared to, say, a non-adjusted Star 48 burn to a transfer orbit on a Delta II mission).  Note also that the number of hydrazine tanks for the thrusters and RCS could be varied depending on the mission.

 - Ed Kyle
« Last Edit: 09/05/2014 06:06 PM by edkyle99 »

Offline edkyle99

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Re: IUS Q&A
« Reply #8 on: 09/06/2014 07:55 PM »
Another set of Qs on the IUS:

1: What was the length of the interstage structure?
I'm still digging for this number.  It is surprisingly hard to find.

Based on a couple of early 1980s users guides, neither of which spell out this dimension specifically, my best estimate is that the 92 inch diameter cylindrical interstage part was nearly 70 inches long (I currently guess 69.89 inches) and was topped by a flared conical section that was 11.6 inches tall and 100 inches diameter at its top.  Note that an extension of this conical flared section (20.2 inches tall and flaring out to 114 inches diameter) was part of Stage 2.  It housed the Equipment Support Section.

Quote
Quote
2: Extension time of the SRM-2 EEC?
17 seconds, according to an old user manual.  It took place immediately after staging.  The Stage 2 burn did not start until about 2 minutes later.
Quote
3: Specific impulse and thrust of the REM thrusters?
I haven't found a listing, but I did find that the post Stage 2 vernier burn lasted 6 m 40 sec and used 94.5 pounds of propellant (using multiple REM thrusters).  The thrusters used hydrazine (N2H4) mono-propellant.  Typical ISP for such thrusters is 220-230 seconds, give or take.  I found one mention of Kaiser-Marquardt as the thruster manufacturer, but no details.

 - Ed Kyle
« Last Edit: 09/06/2014 08:08 PM by edkyle99 »

Online DaveS

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Re: IUS Q&A
« Reply #9 on: 09/07/2014 10:27 PM »
Thanks Ed! Just to make sure I have gotten things right: There's a ring at the top of the conical section of the interstage and it's that one that is 100" in diameter? Or is it the where the conical section meets this ring?
"For Sardines, space is no problem!"
-1996 Astronaut class slogan

"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 edkyle99

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Re: IUS Q&A
« Reply #10 on: 09/08/2014 12:03 AM »
Thanks Ed! Just to make sure I have gotten things right: There's a ring at the top of the conical section of the interstage and it's that one that is 100" in diameter? Or is it the where the conical section meets this ring?
Here's a drawing that shows how the conical (flared) section split into two parts, the top part was part of the second stage and the bottom part was part of the interstage (which itself remained attached to the first stage).  The widest part, at the top, the "spacecraft interface plane", was 114 inches in diameter.  The diameter at the stage separation plane, where the two IUS stages separated in the middle of the flared section, was 100 inches by my best estimate.  The diameter at the bottom of the conical section was 92 inches, which was also the diameter of the cylindrical interstage section.

 - Ed Kyle   
« Last Edit: 09/08/2014 12:12 AM by edkyle99 »

Online DaveS

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Re: IUS Q&A
« Reply #11 on: 09/08/2014 12:12 AM »
The arrows in the attached photo shows the ring or flange I'm talking about. I know that one is part of the interstage, but is it the quoted 100" OD?
"For Sardines, space is no problem!"
-1996 Astronaut class slogan

"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 edkyle99

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Re: IUS Q&A
« Reply #12 on: 09/08/2014 12:31 AM »
Here's a beautiful image of IUS-15/TDRS-E (5) during STS-43.  A close look at the ring shows that the outer mold line of the trunnions and stiffeners, etc., doesn't run exactly parallel to the inner surface of the conical (flared) section.  My 100 inch estimate was based on a straight line running between a 114 inch top diameter and a 92 inch bottom diameter at the top of the cylinder.  Thus, the ring you point to could be a bit bigger than my estimate.  We really need to see some detailed Boeing drawings, or get our hands on an IUS, to know for sure.  There are one or two IUS mock ups out there in museums.  See, for example, http://www.museumofflight.org/category/collections-locations/restoration-center-everett

Keep in mind that there were small, detail differences between Shuttle and Titan launched IUS, and possibly even between Titan 34D and Titan 4 versions.  Note that the IUS exhibit in Seattle doesn't have this ring, which may have been for STS only.  http://www.collectspace.com/images/news-110912c-lg.jpg

I'm also adding a blurry image of an IUS second stage, which shows the second, inner, hidden conical section.

Might anyone have on hand an old copy of an IUS/TDRS (or IUS/anything) "Cargo Systems Manual"?  Those documents usually had detailed dimensional drawings of Shuttle payloads.

 - Ed Kyle
« Last Edit: 09/08/2014 12:55 AM by edkyle99 »

Online DaveS

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Re: IUS Q&A
« Reply #13 on: 09/08/2014 12:53 AM »
To me it looks like the ring is almost or the actual 114" OD of the top of the ESS. And yes, some sort of CSM is high on the wish list here.
"For Sardines, space is no problem!"
-1996 Astronaut class slogan

"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 edkyle99

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Re: IUS Q&A
« Reply #14 on: 09/08/2014 04:47 PM »
This may or may not help.  It is a drawing from the environmental impact statement for the IUS/Galileo mission.

 - Ed Kyle

Online DaveS

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Re: IUS Q&A
« Reply #15 on: 09/08/2014 11:18 PM »
Ed, do you have a number on the ID on the ring with the arrow pointing to it? If I have gotten things right, the ESS part of the second stage rests on it when the two stages are still together.
"For Sardines, space is no problem!"
-1996 Astronaut class slogan

"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 edkyle99

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Re: IUS Q&A
« Reply #16 on: 09/09/2014 03:51 AM »
Ed, do you have a number on the ID on the ring with the arrow pointing to it? If I have gotten things right, the ESS part of the second stage rests on it when the two stages are still together.
I found some more dimensions in the following document at DTIC
http://www.dtic.mil/docs/citations/ADA318329

It includes some detail of the Stage 1/2 separation plane (STA 359.0).  It seems to show a roughly 102 inch flat surface diameter and a roughly 111 inch maximum outer diameter at the ring.  The extreme top part of the ESS is about 110 inches in diameter at the flat surface, and thus would presumably extend out to the 114 inch OD previously mentioned, if not further.  A lot of detail surfaces on this thing!

 - Ed Kyle
« Last Edit: 09/09/2014 04:03 AM by edkyle99 »

Online DaveS

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Re: IUS Q&A
« Reply #17 on: 09/09/2014 05:52 PM »
Found this document on DTIC: http://www.dtic.mil/docs/citations/ADA318331
It contains alot of nice schematics. And according to it, the entire interstage structure is 80" in length running between STAs 279.0 and 359.0.
"For Sardines, space is no problem!"
-1996 Astronaut class slogan

"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

Online DaveS

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Re: IUS Q&A
« Reply #18 on: 09/09/2014 08:25 PM »
Any guesstimates on interstage stringer distance? This could be calculated by the taking the number of stringers and dividing it by 360.
"For Sardines, space is no problem!"
-1996 Astronaut class slogan

"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 gosnold

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Re: IUS Q&A
« Reply #19 on: 11/22/2014 06:41 PM »
Does anybody know how long an IUS (or any other solid rocket motor for that matter) can stay in space and still remain operational?

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