On Jun 6, 3:21 pm, Buy_Sell <werksp...@[EMAIL PROTECTED]
> wrote:
> Once again, I have to agree with what you are saying. However, there
> must be a way to achieve this without inducing excessive drag. If you
> watch enough science-fiction, you might come to the conclusion that
> mankind is doing it all wrong. We should be using "magnetics".
> There must be a way of reducing the drag created by the prop itself.
> The prop itself is the generator of the noise. If you feather a prop,
> it doesn't make much noise but once the prop is pitched to move the
> air, the associated friction is somewhat responsible for the noise
> being generated. This is of course, when the tip speed is below
> mach. As discussed in an earlier post, the owl is one of the most
> stealthy birds because of it's tattered feathers. I can just imagine
> that either a hairy prop or dimpled prop would reduce the noise
> factor. Efficient thrust aside, the desire is to make an absolute
> stealthy hovercraft.
I can only go so far with you here.
I used to get caught up in sci-fi with the wildly improbable stuff. I
still like sci-fi, but I try to filter out the wildly improbable.
Yes, today's sci-fi is tomorrow's science, but they take the only
moderately improbable to make science out of.
My understanding of things is that drag and lift are two sides of the
same coin. Having lift without drag would be a perpetual motion
machine, which I for one Do Not Believe.
I drank that kool-aid back in the 5th grade with a permanent magnet
motor as a science experiment. It consisted of two boards, one nail,
a bunch of magnets and a strip of lead. It took me years to figure
out why I got a perfect score on that experiment when it didn't work.
My classmates ridiculed me horribly even when they had worse scores.
Back to the point, though, yes you can improve a propeller. That's
what I said in my previous post. Yes, you can improve the duct.
Feather the edges, do whatever unsteady flow magic you need to do.
My main point restated is that once you have noise, then you have an
energy state which you must expend energy to correct. If you avoid
making the noise in the first place that is always preferable to
muffling noise after it's made.
In my book, a stealth hovercraft is one which the people on the shore
can't hear until you come around the bend. Some have commented that I
already have that.
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