I've heard it in the air.

Gary

T o d d P a t t i s t wrote:
Andreas Maurer wrote:

As John already
pointed out, you need only a small differential positive pressure to
blow up your wing.

According to the manual, my Ventus wing will withstand an
overpressure of about 3 feet of water or roughly a tenth of
an atmosphere. That's about a pound and a half per square
inch. My vent hole is roughly 0.2 inches in diameter, or
only 0.03 square inches in area. Thus, the plastic should
burst when .045 pounds or about 3/4 of an ounce of pressure
is applied to the area of the small vent hole. Otherwise,
I'd be outside the manual limit on overpressure. I doubt
the ZipLoc plastic is that weak.

OTOH, it's not clear how good of a seal you get with air
attempting to escape. Perhaps a small hole in the plastic
would assure minimal leakage of water when the "one-way"
valve is sealed and still allow rapid dumping.

I heard a wing crack during water filling (from a hose)
without adequate pressure relief. It's a pretty sickening
sound. As much as I like the nifty design here, I'd really
hate to hear it on something I owned while I was in the air.

I'd strongly suggest to email Shempp Hirth about this topic - you
should get a reliable answer quickly.

It would be nice to get a solid answer, but I doubt they're
going to say "Sure go ahead." without some reasonable
testing, and that costs money. You're more likely to be
referred to the manual that already has overpressure
guidelines related to filling the ballast tanks.