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Old Jan 30, 2009, 12:19 PM
Knobbs
Friday Harbor, WA -San Juan Island
Joined Aug 2008
479 Posts
Help!
Evo 9 Dual Elev Servos-Mix w/rudd help

Hi all, I've been doing the best I can to learn this radio theory, the Multiplex thought process. I've learned a lot from Joedy's tutorial, but there is one thing has me stumped. Here goes:

Giant scale Yak- Two elevator servos
One normal direction, one reversed
Plugged in to separate channels on Rx
Elev works great until...

I built a mixer to add elevator while knife edge (rudder)
It works as far as the percentages of travel, but, the servos for separate elev halves go in opposite directions. Well I haven't looked if the SERVOS actually go in opposite directions--not the point--control serfaces go in opposite directions.

So---how come the mixer does not maintain the direction to keep that one servo reversed? Do I need TWO mixers for one simple elev/rudd mix?
Please help>> Thanks Rishelman
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Old Jan 31, 2009, 05:03 AM
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GlowFly's Avatar
Midlands, UK
Joined Jun 2004
1,337 Posts
Did you add 'Rudder' or 'Rudd -Tr' to your ELEVATR+ mixer?
--
Steve
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Old Jan 31, 2009, 07:44 AM
My other TX is a P4000.
Joedy's Avatar
USA, VA, Raphine
Joined Sep 2002
2,254 Posts
I would suggest two mixers in this case.

By default, most elevator servos are intended to work in tandem, not in opposite like aileron servos are.

-joedy
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Old Feb 01, 2009, 03:39 PM
Knobbs
Friday Harbor, WA -San Juan Island
Joined Aug 2008
479 Posts
Quote:
Originally Posted by GlowFly
Did you add 'Rudder' or 'Rudd -Tr' to your ELEVATR+ mixer?
--
Steve
I added 'Rudder'. Not real clear on what purpose the 'without trim' function serves. Educate me please.
Thanks. Rishelman
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Old Feb 01, 2009, 03:41 PM
Knobbs
Friday Harbor, WA -San Juan Island
Joined Aug 2008
479 Posts
Quote:
Originally Posted by Joedy
I would suggest two mixers in this case.

By default, most elevator servos are intended to work in tandem, not in opposite like aileron servos are.

-joedy
I was afraid of that, just hoping to not burn two mixer slots for one mix.
Thanks. Rishelman.
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Old Feb 02, 2009, 12:02 PM
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Joined Apr 2004
68 Posts
to control pitch coupling(elevator) you only need one mixer not a different mixer for each elevator half. You can get different values for both left to right knifedge and right to left.

to control roll coupling you may need two mixers, one for left wing and one for the right wing. If you need to compensate different amounts for both left to right knifedge and right to left then you will need two mixers. I am only using one mixer for aileron also !! I use the same percentages from left to right and right to left. You will never get it perfect anyway so i get it close and compensate with my flying skills to clean it up.
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Old Feb 02, 2009, 04:00 PM
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GlowFly's Avatar
Midlands, UK
Joined Jun 2004
1,337 Posts
Quote:
Originally Posted by Rishelman
I added 'Rudder'. Not real clear on what purpose the 'without trim' function serves. Educate me please.
It means that as you adjust the Rudder trim with the trim buttons, it won't also affect any mixer that uses it - like Elevator in your case. The normal Rudder input includes the trim offset - that may not be your intention.

The reason I asked which you used is that from memory the two are treated differently within the Evo as far as left/right coupling is concerned. I can't test it at the moment since I upgraded to Pro which behaves differently.
--
Steve
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