Newsgroups: comp.robotics
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From: djbarnes@eos.ncsu.edu (DONALD JAMES BARNES)
Subject: Re: Flying robots...
Message-ID: <1993Feb19.185609.10714@ncsu.edu>
Originator: djbarnes@c00484-224wi.eos.ncsu.edu
Sender: news@ncsu.edu (USENET News System)
Reply-To: djbarnes@eos.ncsu.edu (DONALD JAMES BARNES)
Organization: North Carolina State University, Project Eos
References: <1lv6npINNbkd@bowen.rick.cs.ubc.ca> <1m1b2f$77c@bigboote.WPI.EDU>
Date: Fri, 19 Feb 1993 18:56:09 GMT
Lines: 45


In article <1m1b2f$77c@bigboote.WPI.EDU>, jimzad@bigwpi.WPI.EDU (James Peter Aduskevich) writes:
> > - Anybody with experience in small, light-weight yet powerful fans that may be
> >   appropriate for this construction?
> 
> It depends on the amount of thrust you want, but a 05 size eletric motor (used
> in most good R/C cars-available at most hobby stores) with a model airplane
> prop attached would give a lot of thrust and is relatively inexpensive.  The
> weight is not too bad; the main problem is they draw a lot of current (1200 mah
> batteries usually last about 7-10 min)
> 	Another idea (for less power/draw) is a prop from a rubber-band powered
> plane on a small motor (look in Radio Shack, they have a few different types).


If you don't mind spending the money once, you can be the modified model of the
05 styled RC motor for around $50 mail order.  Sounds steep (unless you race
RC like I do), but these motors are easily rebuilt and are bearing motors.  They
also have adjustible timing that will allow you to adjust the power output thus
adjusting the current draw.  These motors are the most efficient of their size.
And as for batteries, RC racers now use 1500mah packs that can be quick recharged
over and over and still retain their life.  For the same money, you can get 1700
mah batteries that can stand only one charge per week, but last much longer.
I would estimate that you could power one motor running a fan at moderate speeds
off a 1500 pack for over 45 minutes (including, say, a miniboard to control).

Another thing to think about is the speed control.  RC racers use highly 
sophisticated electronic speed controls that have near zero voltage drops and
are fully adjustable.  These units are very small, and can be controlled as if
they are simple servos.  A recent post was that software was in the works to 
control servos with the miniboard.  My opinion is that one motor and two servos
to possibly control two servos for two rudders might be a good way to control
one of these things.  (Of course, my only dealings with flying devices was the
crash of an RC airplane that I built when I was 15 on its maiden voyage, so I
may not be the best one to give advice.)  

If anyone wants any other info on RC devices, just email me.  After all, they
are almost robots:-)

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                         |
Donald Barnes	         |     	"You can think about it, but don't
djbarnes@eos.ncsu.edu    |
N.C. State University    |			do it."--Smokey
                         |
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