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Trim tab controls

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Lew Gallagher

Joined: 04 Jan 2008
Posts: 402
Location: Greenville , SC

Posted: Tue Jun 07, 2011 10:16 am Post subject: Trim tab controls

Hey Guys,



I've about finished up with Linn's idea of using a micro controller and RC servos to operate a small tab extension on the aileron and rudder.



Here's a first, somewhat crude, youtube video of my demonstrator: 



 http://www.youtube.com/watch?v=rPFUCQeOM4Q 



The servos are digital, high torque (88.88 oz-in) that weigh 1.59 oz.  They are not like the old analog servos -- they don't "hunt". They have carbonite gear sets and there are metal control arms available.  The idea is that they are light weight enough to mount on a small access panel inside the rudder and aileron.  The digital readout can be customized to pretty much whatever the pilot wants -- or to a bar LED like the one supplied for the elevator trim.  I like the digital cuz it gives a much more refined position, and cuz it was more of a challenge, but I'm aware that most pilots probably would see that as a distraction.



The switches would be incorporated into the hat switch, toggle on the stick, or on the panel.  Brightness of the digital display is controlable.  I was concerned that the signal to the pulse motor servos might be compromised by the length of the wire, so I put 25 ft. on each -- and they work fine.



I programmed in the feature to "save" the position you want, so that you don't have to reset the trim every time you start up the plane (i.e., the basic program sets the servo to neutral each time it powers up).



I got most of the materials off Ebay and RadioShack for the demo. Probably around $100.

The brain of the system is the Parallax BS2 micro controller and I've built in the MAX7219 8-digit display driver to control the digital displays.  I started from zero and taught myself enough Pbasic to program this thing to do  what I wanted it to do -- WHAT A BLAST!!



If I can talk Wes into it, I'll probably build these into an aileron and the rudder that I have for the next -10 I'm building, then swap them out in his plane to see if they work.  If they don't or no one likes them, it's still been an awesome project.

Later, - Lew

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_________________
non-pilot
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NOW OFICIALLY BUILDER #40549
Fly off completed !

rbibb

Joined: 16 Jul 2009
Posts: 37

Posted: Mon Jun 20, 2011 7:15 am Post subject: Trim tab controls

Had the same idea awhile ago - can you supply mfg pn on servoes?



Richard Bibb

571-379-3290 mobile

 

 

--

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Lew Gallagher

Joined: 04 Jan 2008
Posts: 402
Location: Greenville , SC

Posted: Mon Jun 20, 2011 1:49 pm Post subject: Trim tab controls

Hey Richard,



The servos are Hitec HS-5485HB.  Let me know if you get something tested in 

flight.



Later, - Lew

---

- The Matronics RV10-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?RV10-List

_________________
non-pilot
crazy about building
NOW OFICIALLY BUILDER #40549
Fly off completed !

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