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Gemstone
2003-Feb-20, 02:58 AM
Maybe someone here can explain something to me... If the space shuttles tires are inflated to some pressure, say for example, 30 PSI, how do they not explode when they enter the vacumn of space?... Or are the wheel bays always pressurized?... I don't understand how this works... If you pull a vacumn on an inflated balloon it's going to go POP!

joema
2003-Feb-20, 03:38 AM
The shuttle tires are inflated with nitrogen to 315 psi. The wheel wells are not pressurized so when on orbit the tires are in a vacuum. Plus or minus 14.7 psi doesn't make much difference when the tires are at 315 psi.

copabera
2003-Feb-20, 05:08 PM
Gemstone wrote:

If you pull a vacumn on an inflated balloon it's going to go POP!

Not necessarily. Depending on what the balloon is made out of, the balloon might inflate more, maintaining roughly the same pressure. If the balloon is made of a more rigid material (like a steel-belted radial tire), then, as joema pointed out, the pressure differential will simply increase by 14.7 psi. This has the same affect of over-inflating any ground-based tire by the same amount: They won't "pop".

BTW, I live at an altitude of 7400ft. Whenever I "drive down the hill", the tires on my car along with toys I'm carrying such as beach balls, soccer balls, etc become noticeably flatter. I keep an air pump in the car just to keep things inflated properly: a real pain.

On the other side, when a package arrives at my house the air-tight plastic bags contained therein are usually hyper-inflated, sometimes to the point where they "squish" the other contents of the package. But I have never seen any poppage.

Resu
2003-Feb-20, 05:25 PM
right, the balloon wont necessarily to pop giving the strength of the material the balloon is made of.

it is the net pressure that matters.

Gemstone
2003-Feb-20, 11:19 PM
Got it!! I should have known that!