How much weight did NASA "save" by not painting the Shuttles Ext.Tank?

[Up2Late]

Does anyone know; how much weight did NASA "save" by not painting the Shuttles Exterior fuel Tank?

I had an idea last night, and posted a question in GD, I got some good responses, but I think it's time to pose the questions to the Science Forum.

Below is the text of my original post and am adding the question above to these below.

A link to the original post is at the bottom.

Hey! I just thought of a simple way to fix the Shuttles "Foam Problem"

Remember when they first launched the Space Shuttle back in 1981?

Remember what they changed on the Second Space Shuttle Launch, and everyone after that?

Give up?

They Painted the First Shuttles "External Fuel Tank," but they stopped painting the tanks, after the first one, to save time, labor costs, and Weight. Some of you are probably saying weight, how much weight could paint add?

In two words, A Lot, but really not that much considering that a lot of other things (like Computers) have improved and become lighter.

And WHY would this fix the problem? Because it would create a very thin, Hard, paint sealing shell, sealing in any imperfections in the foam. :think:

And they might not even have to paint the whole tank, just the problem areas!

What do you folks think, any reasons why this wouldn't work or be completely wrong? :shrug:

<http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=104&topic_id=4266037&mesg_id=4266037>

[salvorhardin]

1. IIRC correctly it was about 600 pounds

that was shaved off the launch weight of the STS. There have been two subsequent rounds of improvements in the manufacture of ETs that have shaved an additional 17,000 pounds off the combined weight of the STS.

I don't know, but I would be surprised, if the paint would help at all. I'll check a couple of references and post again if I can find anything worthwhile.

On edit: It was 595 pounds for a costs saving of $15,000.

On second edit: The reason for discontinuing the paint was not just to save a measly $15K out of a ~$250M launch budget. It also improved flight performance. Obviously, with ETs that weight about 17K pounds less than they did in the early 1980s, and with the better flight software NASA is using today (which means more efficient use of propellant) this is not so big an issue now.

[Up2Late]

5. Wow, that's not much!

Sounds like this is an idea that would be worth NASA's consideration and testing.

Let me know what you find.

[tridim]

2. My idea still stands..

A gigantic nylon "stocking" covering the entire tank. The drag couldn't be much worse than the foam surface alone.

Of course ideally, they should hire Burt Rutan, start from scratch and redesign the whole program.

[Up2Late]

3. Your idea was one of the ideas that sparked mine!

I thought, yeah, but how much weight would that add? And, like you said, what about the extra drag.

Someone else suggested adding long fibers to the foam mixture, and then I though, Hey! Maybe they should just paint the Tank again.

Back in 1981, other than saving weight, they wanted to cut turn-around time to get the shuttle back into space faster, when they were trying to meet their, "Shuttle Flights as common as flights to Europe" or what ever it was.

Now that we realize Safety is more important than bragging rights, I think they have time to paint the tanks, and it might help.

[salvorhardin]

4. Minor correction

The first 2 shuttles flew with painted ETs.

[Up2Late]

6. Did they notice any foam shedding on the first two fights?

I heard last night that they have had a lot more foam shedding than has been reported to the General Public.

[salvorhardin]

7. IIRC The first two flights did shed foam -- and paint chips/flakes as well

There has been no effort to keep any information from the general public. Foam, and tiles, have been falling off the STS from the beginning.

Incidentally, the white color of the paint also helped reflect the sun and keep the foam from heating up but again this is probably no longer an issue.

Henry Spencer had this to say in a 1998 usenet post:

Incidentally, the reason that the early ones were painted was not that NASA was stupid, but that the early test flights were expected to spend a long time on the pad before launch, and there was some concern about weathering of unprotected insulation. The change was possible partly because pad times were getting shorter (as expected), and partly because improved knowledge of the insulation's weather resistance cleared it for reasonable exposure times.

http://groups-beta.google.com/group/sci.space.shuttle/msg/ac08f0ab53826652?dmode=source&hl=en

[Up2Late]

8. The Henry Spencer comment does bring up another issue...

...or idea, I wonder if the relatively long time between the first roll out of this Shuttle (APRIL 7, 2005) and its final launch, almost FIVE (5) months later (July 27, 2005), could that be the factor that was not taken into account?

That's a LOT of time in the Florida Weather, and in the salt air of the Ocean, including one passing Hurricane.

Maybe it SHOULD have been painted? It looks like they were only planning for it to be on the pad until mid May!

How long did they determine was an acceptable amount of weather exposure, back when they were discussing this? :shrug:

<http://www.cnn.com/2005/TECH/space/04/06/shuttle.rollout/index.html>

Shuttle rolls to launch pad

NASA: Crack found in external fuel tank not an issue

By Michael Coren
CNN
Thursday, April 7, 2005 Posted: 10:02 AM EDT (1402 GMT)

(CNN) -- Since the loss of Columbia in 2003, thousands of people have spent the past two years working to make the space shuttle a safer vehicle.

That labor inched closer to payoff Wednesday afternoon when Discovery, with its two solid rocket boosters and external fuel tank attached to its belly, rolled out of the Vehicle Assembly Building (VAB) at 2:04 p.m. EDT for a four-mile journey to the launch pad at Kennedy Space Center in Cape Canaveral, Florida.

A crawler transporter moved the shuttle to pad 39B where it will sit until launch -- set for no earlier than May 15.

(more at link above)

<http://www.cnn.com/2005/TECH/space/07/26/space.shuttle/index.html>

Shuttle returns to space

NASA examining video of debris spotted during liftoff

From Thom Patterson
CNN
Wednesday, July 27, 2005; Posted: 12:01 a.m. EDT (04:01 GMT)

KENNEDY SPACE CENTER, Florida (CNN) -- Discovery roared into orbit Tuesday in NASA's first shuttle flight since the 2003 Columbia disaster, and afterward engineers began evaluating pictures of falling debris to determine the chances of another mishap....

(more at the link above)

[Up2Late]

9. Anyone know an e-mail address for someone important at NASA?

I keep hearing them say, they don't have any ideas right now, regarding the foam.

I really think they should consider what we have been knocking about here.:shrug: