Subject:
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Re: "real" LEGO Hovercraft ? (with/without batteries/RCX "onboard")
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 29 Nov 2002 15:05:23 GMT
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Viewed:
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5852 times
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but wher is the fun?
my skirt has been done as a cut of the sphere
the same shapa as the tunnel has to hav (i think)
so it was a middle part of sphere without upper and lower domes
that's why i said "a little bit hard to do it" :))
you said CD is too big
?
CD has 5 1/4 inch so it's not much bigger than you said - 4 inches
but i suppose you are right!
have a look here
http://web.mit.edu/sp.742/www/motor.html
i must check the weight of lego-motors to use your formulas
but they are useful - thanx
i've been trying 12V
and read somewhere that 18V quadruple torque!
so:
aprox:
0.37W * 4 = 1.5W
and 1hp = ca 750W
so lego motor has 0.002 hp
so
we can lift ca 0.3lb
so i think lego motor cannot lift itself
so end of topic isn't it?
the answer is: you stole whole fun from this issue :((((
and now - me too :(((((((((((((
:)
best regards
pixel
"Jim Choate" <lego-robotics@crynwr.com> wrote in message
news:Pine.LNX.4.33.0211290805310.1275-100000@einstein.ssz.com...
> On Fri, 29 Nov 2002, pixel wrote:
>
> > 1. pure turbine has to be placed in some kind of tunnel but not exactly
> > funnel
> > the tunnel has to be as a part of ball (sphere) without hats :)) at • the
> > upper and the lower side
> > because the stream of air has to compact and air cannot escape near • the
> > blade of rotor or turbine
>
> Bingo.
>
> > 2. lego motor http://peeron.com/inv/parts/2838c01 is the only one useful
> > because the new motor has no enough speed
>
> Take a look at some of these micro motors that are being used in the new
> mini-RC cars. You can buy a whole car kit, radio, and controller for about
> $75US.
>
> > 3. propeler has to be non-lego beacause of weight and shape and • stability
>
> A helo tail rotor is your best bet. Wood or a composite is your best bet.
> Stay away from -any- metal blades as they are a serious safety hazard in
> this application.
>
> > 4. turbine can be weighty so motor can rotate it and keep the speed
> > (flywheel)
>
> No, you don't need a turbine. What you're missing is the ratio of the
> inlet area to exhaust plenum area and the delta-v of the air flow.
>
> 200lb's will get a good lift from 1/4hp.
>
> 200lb's weight of hover
> ------- = ---------------
> 1/4hp power of motor
>
> > 5. good turbine is cd-disc :)) cut on chords and bent termicaly (it's • heavy
> > enough) (you need some tools to do it)
>
> Yuck. A CD disk is -way- too big across, and it's aerodynamic efficiency
> is insufficient to move enough air. At high air speeds the flat 'blades'
> will stall and you will find the flow going down with increases in fan
> speed. Your fan shouldn't be more than about 4 inches across.
>
> > 6. for me it's impossible to do lego frame light enough (in fact lego • parts
> > are heavy especialy axles)
>
> I suspect this isn't true. I'd start with a standard green plate and
> eschew the whole idea of a frame, insufficient rigidity in Lego plastic.
>
> > 7. making skirt is very important (i did it from plastic bag) it's a • little
> > bit hard to do it
>
> Shouldn't be. I'd suspect it's your process, remember you -must- pleat the
> corners or the skirt will dump. Hint, the pleats -must- be vertical with
> respect to the running board/ground reference frame.
>
> If you're making a tubular skirt then you want to make it in eight (8)
> seperate sections. Four (4) straight tubular pieces, use a wood dowel
> or a similar form to make. Then the four (4) corner pieces.
>
>
> --
> ____________________________________________________________________
>
> We don't see things as they are, ravage@ssz.com
> we see them as we are. www.ssz.com
> jchoate@open-forge.org
> Anais Nin www.open-forge.org
>
> --------------------------------------------------------------------
>
>
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