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 16:37:16 GMT
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Original-From:
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Jim Choate <ravage@einstein.ssz.ANTISPAMcom>
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Viewed:
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3468 times
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On Fri, 29 Nov 2002, pixel wrote:
> but wher is the fun?
You'll have to answer that for yourself. A lot of what I find fun would
probably bore/scare most to death. For example, I find all these
transformers and such that a lot of Mindstorm folks rave over completely
and utterly uninteresting, and I'm a major Transformers (c) freak. If you
like 'em, rage on. I also find the Brick to be a toy (Styx-on-a-Brick
being the major exception) and not worth the effort to mess with, though
the Lego pieces themselves are great!
> 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" :))
Last time I checked a sphere didn't have a 'middle' per se. The piece
you're talking about is a rubber sheet toroid. Also, there is a specific
term for the 'upper and lower domes'...;)
> 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!
That extra inch is a problem (pi*r^2), a 5in circle is a -lot- bigger
than a 4in circle. A similar problem a lot of folks have is e=m*v^2.
In general they spend way(!!!) too much time playing with m when they
should be looking for improvements in v since it grows much faster (Hint).
The show stopper for using a CD is that it has zero aerodynamics. Flat
plates don't move air well, most especially at high speed (there's that v
again...).
> i must check the weight of lego-motors to use your formulas
> but they are useful - thanx
NO...the 'mass' of the hovercraft is what you want compared to the torque
of the motor coupled with the efficiency of the air handling.
Force over area is what you need to pay attention to.
Also, they're not my formula. They come straight out of any physics book.
> i've been trying 12V
> and read somewhere that 18V quadruple torque!
That would depend on the motor design I suspect.
> 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?
A simple experiment with levers and pullies....you forgot
time. Horsepower is a -time dependent- quantity. I can say that you can
build a rope climber with Lego (and that requires a motor to lift it's own
weight and then some).
> the answer is: you stole whole fun from this issue :((((
> and now - me too :(((((((((((((
-You- asked, be carefull for what you ask. You might get it. I can't
help it if hovercraft are a major interest of mine (check out the roll in
the new James Bond movie, I think that is a first).
--
____________________________________________________________________
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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