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 14:04:09 GMT
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Original-From:
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Jim Choate <RAVAGE@stopspamEINSTEIN.SSZ.COM>
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Viewed:
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766 times
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On Sat, 30 Nov 2002, SuperFly wrote:
> i want to do it but i think we would have to figure out the power to weight
> ratio does anyone no the formula
It's not one formula.
The first hurdle is to balance the force of gravity.
F=ma
m is the weight of the hovercract assembly.
a is the -negative- acceleration due to gravity.
F is the total force the fan must provide.
Then you've got to figure for a given fan/rpm design what
the air flow is.
Then you've got to figure out what force that will generate
(F=ma again) over the area of the plenum. You can assume that
the air at the -input- side of the fan has a=0.
Then you've got to figure how the force/area is going to change
from the inlet plenum to the effective area of the skirt bottem
(ie the area of the running board).
Then you've got an efficiency figure to calculate (different for
each skirt design and surface the skirt moves over). For a fixed
rpm design like this will likely be this step is really
irrelevant.
Note that this is a static, steady state design. All these numbers
change the moment the hover begins to move and the temperature and
air pressure are reasonably constant, and it gets even more complicated
when it turns.
Your time would be better spent experimenting as compared to
pushing keys on a calculator (I use Scientific Notebook).
--
____________________________________________________________________
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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