Aim

• To test at what pressure a reinforced bottle will fail.

Experiment Setup

The standard hydrostatic burst test procedure was used to carry out these tests. (See above)

The bottle re-enforcement technique based on Richard Wayman's technique described here:

http://wrockets.trib-design.com/index.php?project=RICHARD&page=hp

We used a 1.25L bottle with one half of the jacket made from a 1.5L bottle, and the second half (the neck) from another 1.25L bottle. Because we don't have a heat gun we used hot water instead to shrink the outer bottle. It gave a very satisfactory result.

	Re-enforcing a bottle with another bottle.
	They loosely fit together, and then the outer jacket is shrunk over the inner one.

Results

	On the test stand.
	The top jacket separated. This will need a bit more work.
	Stress fractures from 220 psi near the top of the throat. The bottle did not break.

We had three attempts at blowing it up but on the first attempt the hose released the nozzle at 160 psi. On the second attempt a connector broke at a thread on our pressure regulator at 200psi most of the water was drained from the bottle through the pressure bleed valve.

On the last attempt at 220psi the bottle again separated from the hose, and although there was virtually no air in the bottle, the bottle took off and skidded along the grass for about 15 meters. We will attach the hose properly next time through a different connector.

Conclusion / Analysis

Looking at the bottle after the tests it was obvious that this is likely to be a very good technique for building rockets that fly at 200+ psi. The top part of the jacket separated, but that is likely to be improved with larger overlaps, and perhaps glue.