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#11
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"Stephen McNaught" wrote in message
... Might be bad in case of electrical failure. What about having two "opposite" bleeder like valves, that when there is a pressure difference, one opens up to equalize the outside, and inside of the floats? Well, first...what you're talking about would be simply an open passage. So forget the "two 'opposite' bleeder like valves" idea. If you have two valves, one of which allows air movement with a negative pressure difference and one of which allows air movement with a positive pressure difference, then you just have the equivalent to an open passage for air to move. Second, for it to work, you'd need a float that worked correctly when inflated only to ambient pressure. Most "inflatable" objects (the floats in question included) generally maintain a higher pressure inside than ambient, and this is what gives them structure. It wouldn't be appropriate to operate the floats when the internal pressure is the same as ambient pressure. You really need the internal pressure to remain at least somewhat higher than ambient. Third, an inflatable object is pretty good at resisting an internal pressure higher than ambient, and a calibrated valve certainly would allow one to maintain any specific pressure or relative pressure difference desired. But it would be hard to get the internal pressure *below* ambient, which would be required in order to allow external air to flow back into the object. Without any structure built into the object to prevent it from collapsing (such as that found in self-inflating camping bedrolls, for example), an increase in ambient pressure would simply make the object smaller. It wouldn't take on more air. There are a variety of solutions to dealing with the pressure changes due to altitude. But in general, they all involve enough complexity and weight that you're better off just getting rigid floats if you anticipate significant altitude changes. Inflatable floats do exist, and they are appropriate solutions for some aircraft, but just not those that climb any significant amount. Pete |
#12
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George Patterson wrote:
I wonder if it would be possible to make inflatable floats that could be deflated once in the air to reduce drag. Maybe a little electric air pump to inflate them again before landing? I looked at a T-Bird II that was forsale, it had inflatable floats that were fed from the exhaust of the Rotax engine. Didn't look closely at the rigging for that as it was hanging from the roof of the hanger... The owner was deceased, but seller attested to seeing it work as setup... |
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