Servo Types

[Ryan Wiesehan]

Hello,
I tried to research this on my own without rehashing servo talk on the
list, but I couldn't find an answer that satisfied my curiosity.  I will
outline my research first so that you may better help me out.  I want to
put new servos in my Used Summit III, it has 148's in it now and I think
it flies great, no problem with torque, and there isn't a centering
problem between days and flights.  But, I am always hearing that better
servos will make you fly better.  And I want to be a better flier.  So,
I have spent the last three weeks researching servos.  This research
must be one of those instances when you are confused because you are
paying attention.  I want is spend less than $180, $25 - $40 per servo
and 40oz ok ailerons, 60oz rudder and elevator.  Here is how it breaks
down in my mind from the research.  
 
1.         The four basic qualifying specs for servos:  speed, torque,
weight and price.
2.         Then you have motor type and non-digital vs. digital.
3.         Lastly, you have brand, and I've tried JR, Futaba, Hitec,
TowerHobbies and Expert.  
 
I am most interested in hearing your opinions about #'s 1 and 2; I don't
really care to debate brand in this thread
 
 
3-pole non-digitals; can have problems centering due to the splits in
the armature.
 
5-pole non-digitals; don't know there isn't really much information.
Would someone help?) I assume they have better centering and maybe more
power than a 3-pole, I am thinking these might work for me so please try
and sell me on the coreless. 
 
Coreless non-digital; has a different armature system without poles that
allows for better centering and a lighter core.  Most of the low end
coreless seem like they are slower than a 3-pole.  I am starting to
thing that the standard specs for speed are misleading. If the coreless
motor is lighter and accelerates more quickly than a 3-pole why does a
$30 coreless post the same specs as $9 el cheapo?
 
Now, here is where I really get confused, change all of the above to
digitals.  If the circuit board is always sending centering and position
location at 3 times the rate previously to a 3-pole motor, why wouldn't
I want to buy it?  It should center fine because with a digital servo
centering is powered. 
 
Wow, sorry, that was a long email.  I guess all that I am asking is for
someone to explain why money spent on servos is valid.  Because, I just
took out my plane last weekend after all this research and I couldn't
figure out how it could be better. 
 
Thanks,
 
Ryan Wiesehan
 
FreightQuote.com
New Business Sales 
 
 
 
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