Subject:
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Re: hoovercraft with lift, thrust and steering
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Newsgroups:
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lugnet.technic
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Date:
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Thu, 6 Mar 2003 22:59:38 GMT
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Viewed:
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2435 times
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In lugnet.technic, Paul Kleniewski writes:
>
> "Øyvind Steinnes" <senniets@online.no> wrote in message news:HBAoL9.9CH@lugnet.com...
> >
> > "pixel" <pixsrv@poczta.onet.pl> wrote in message
> > news:HB9n89.DzD@lugnet.com...
> > > "Paul Krieg" <pdkrieg@epix.net> wrote in message • news:HB9KH9.8H1@lugnet.com...
> > >
> > > > Well, my rotor blades are a bit big (about 12 x 36 L).
> > > oh G! :)
> > > what motor will rotate it?
> > With those big blades you do not need the high speed to get lift, so you can
> > use a geared down motor for this I think? But that sounds more like an
> > helicopter then an hoovercraft...
>
> when we see helicopters
> they have slim blades with very high rpm
> so i think wide blades are not too good
> but keep working...
I think one reason helicopter blades are so thin is because they are
changing pitch every cycle with the cyclic control. Thicker blades would
require much more torque to change the pitch, making the hub much bigger.
Also the length of blade required means wider blades would be impractical.
> i saw few applications just prototypes
> (maybe it was just picture)
> of an helicopter with jet engines
> ther the blades was wide because the stop diring fly
> and then they was acting as wings
>
> but you know it was jet-something machine so... :)
>
> > > it has to create much resistance on the air
> > > > They are made this way to save weight as
> > > > your hoover craft is
> > > but it could cause the hovercraft will rotate instead of propeller :)))
> > > (joke)
> > Well it is not a joke, my craft is now so light that it actually spinns the
> > craft almost in about half the speed of the fan if I dont hold it back with
> > something...
> > How can I stop the air under the craft go spinning?
> > Some fins under the skirt hanging down? Some airtunnels going outwards?
>
> 1. do 2 propellers rotating in oposite sides
> 2. do the propeller which will act as small rotor in helicopter (it's just for this effect)
> 3. forme some kind of tunnels inside the body which will redirect the air flow in the oposite side
If the propeller is big, the biggest problem is simply the inertia of the
blades. So #3 wouldnt make much difference, unless you orient the propeller
on a different axis.
ROSCO
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Message is in Reply To:
 | | Re: hoovercraft with lift, thrust and steering
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| "Øyvind Steinnes" <senniets@online.no> wrote in message news:HBAoL9.9CH@lugnet.com... (...) when we see helicopters they have slim blades with very high rpm so i think wide blades are not too good but keep working... i saw few applications just (...) (22 years ago, 6-Mar-03, to lugnet.technic)
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