Servo question

[Glen.Watson at aspentech.com]

Gray,
 
If you are consistently over-rolling I would contribute that to having more
surface deflection and expo than needed.  More expo you add you're more
likely when rolling moving the transmitter stick position into the curve
slope where the servo transitions from the shallow expo curve back to linear
resulting in a hard to manage roll rate.   What I did was reduce the overall
aileron degree deflection using Futaba's AFR function while maintaining 100%
ATV, same can be done mechanically by changing servo horn position, then I
readjusted (reduced) expo amount to taste.  
 
Glen
 
 
-----Original Message-----
From: Gray E Fowler [mailto:gfowler at raytheon.com]
Sent: Friday, August 01, 2003 8:08 AM
To: discussion at nsrca.org
Subject: RE: Servo question
 

Glen 

I have never been able to really reproduce that coreless feel, yet with more
control due to digitals. I added more expo but all surfaces around center
are still more active. I rarely under roll, always over roll. Are you saying
that if I reduce the travel of the servo, yet keep the same surface
deflection that it gets more controllable? If this is the case I should
easily be able to move up from 22nd place to 21st... 



Gray Fowler
Principal Chemical Engineer
Composites Engineering 



 
Glen.Watson at aspentech.com 
Sent by: discussion-request at nsrca.org 
07/31/2003 03:59 PM 
Please respond to discussion 
        
        To:        discussion at nsrca.org 
        cc:         
        Subject:        RE: Servo question



Early this season I swapped my Futaba 9102 coreless wing servos for 9150
digitals.  As Gray mentions I first added more expo to reestablish feel.
With this added expo (mushiness) when doing points and slow rolls it was
difficult to maintain a consistent roll rate.  By decreasing travel volume
(9ZAP AFR) in addition to reducing relative expo, roll rate became more
controllable and predictable. I sense there is a relative amount of travel
volume + expo needed to overcome surface blow back with non-digitals to
achieve desired mushiness. 
  
Switching to digital wing servos has greatly changed the rolling
characteristics for me in a positive way.  Rolls are crisper, more
predictable in all air speeds and stop-start with more authority. 
  
Glen 
  
  
-----Original Message-----
From: Gray E Fowler [mailto:gfowler at raytheon.com]
Sent: Thursday, July 31, 2003 3:04 PM
To: discussion at nsrca.org
Subject: Re: Servo question 
  

What I noticed when switching to digitals was the need to add more
exponential. The coreless had a built in mushiness around center. Now I
program in the amount of mushiness I want. This probably means that once you
get used to a certain mushiness you would fly as well with or with digitals.



Gray Fowler
Principal Chemical Engineer
Composites Engineering 
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