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The Feature Creep

Join Date: Feb 2005
Location: Boston, MA
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Shuttle Foam

08/02/2005 10:43 AM

With all the speculation over the foam used on the space shuttle I decided to look up the technical specs on the foam. This is from NASA's Thermal Protection System.PDF

Some interesting facts:
The housing is actually two layers, it the outer layer comprised of "low-density, closed-cell foam" and a "denser composite material called ablator, made of silicone resins and cork. An ablator is a material that dissipates heat by eroding."
The foam is sprayed on the tank.
"The closed-cell foam used on the tank was developed to keep the propellants that fuel the Shuttle's three Main Engines at optimum temperature."
"The foam insulation must also be durable enough to endure a 180-day stay at the launch pad, withstand temperatures up to 115 degrees Fahrenheit, humidity as high as 100 percent, and resist sand, salt, fog, rain, solar radiation and even fungus."
"Though the foam insulation on the majority of the tank is only 1-inch thick, it adds 4,823 pounds to the tank's weight. Insulation on the liquid hydrogen tank is somewhat thicker -- between 1.5 to 2 inches thick. Though the foam's density varies with the type, an average density is about 2.4 pounds per cubic foot."

So I hope this helps answer some of the questions people might have about why the foam is used and exactly what the stuff is made of.

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The Architect
Engineering Fields - Software Engineering - S/W Architect Popular Science - Evolution - Fascinating! Fans of Old Computers - TRS-80 - A fine computer United States - US - Statue of Liberty - NY

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Good Answers: 5
#1

Thickness seems wrong...

08/02/2005 10:56 AM

The "1 to 2 inches" thick part seems wrong to me... I recall them using pretty big chunks for the chicken gun test, and that was supposed to mimic the actual size that fell off in '03.

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Mark Gaulin
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The Feature Creep

Join Date: Feb 2005
Location: Boston, MA
Posts: 1055
#2
In reply to #1

Re:Thickness seems wrong...

08/02/2005 11:01 AM

Chicken gun? I assume you must be talking about Mythbusters.
As for the thickness, it can get thicker where the ablative coating is needed. The 1-2 inch guideline is for the average, not the high heat areas.

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The Architect
Engineering Fields - Software Engineering - S/W Architect Popular Science - Evolution - Fascinating! Fans of Old Computers - TRS-80 - A fine computer United States - US - Statue of Liberty - NY

Join Date: Dec 2004
Location: GlobalSpec, Troy NY
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#3
In reply to #2

Re:Thickness seems wrong...

08/03/2005 9:44 AM

The chicken gun test is a standand (more or less) in the airline industry, and NASA used the same equipment to shoot the foam at a wing section. (It blew a 10" hole in it.)

I can believe that they did something like that on Myth Busters, but I sort of doubt they used the "real" equipment. Knowing them, before they were done with the experiment they attached a rocket to a chicken, or better yet, to a crash test dummy version of a chicken, with real fake blood inside it!

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Mark Gaulin
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The Feature Creep

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Location: Boston, MA
Posts: 1055
#4
In reply to #3

Re:Thickness seems wrong...

08/03/2005 10:25 AM

Ok, I found one to look at. So this is a chicken gunchicken gun and how it's used. Any yes they do use chicken carcasses in it to hurl at planes.
As for Mythbusters they also had one, but they used it to do the same thing.

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