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  #1  
Old 02-23-2021, 07:36 PM
Acenels's Avatar
Acenels Acenels is offline
 
Join Date: May 2017
Location: Seattle, Wa
Posts: 44
Default Wing vs Fuselage autopilot

I know there has been some debate as to the ease of installation, but I'm most curious if there is a reason not to install in the wingtip.

I am replacing a TruTrak step motor (wing leveler) that was mounted problem-free in the right wingtip. I am upgrading to a full GSA 28 garmin autopilot.

I am debating mounting in the GSA 28 in the fuselage under the passenger seat vs. using the current bracket on the right wingtip. Under the seat would require moving the Comm 2 antenna, which isn't a huge deal.

I realize the fuselage mount is "spec" for garmin, and that trutrak went to a fuselage mount in later designs. My question is "why?" Is there a disadvantage to having the servo out there in the wingtip based on weather elements or something? It would probably be an easier install in the wingtip (and that under seat just looks crowded), but happy to move the antenna and put it under the seat if there is a compelling reason (or vice versa).

Any thoughts?
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  #2  
Old 02-23-2021, 10:04 PM
Taltruda Taltruda is offline
 
Join Date: Oct 2017
Location: Las Vegas, NV
Posts: 639
Default

Which model RV are you talking about? I don’t know anything about mounting the roll servo in the wingtip.. on my RV-8 kit, it gets mounted to the right aileron bellcrank bracket. The pitch servo goes in the fuselage at the bellcrank there. Why do you want to make up your own brackets and get creative when these other locations and brackets are available already?
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RV-8 empenage finished 10-2020

Wings Started.. 11-2020
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  #3  
Old 02-23-2021, 10:43 PM
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Acenels Acenels is offline
 
Join Date: May 2017
Location: Seattle, Wa
Posts: 44
Default

Quote:
Originally Posted by Taltruda View Post
Which model RV are you talking about? I don’t know anything about mounting the roll servo in the wingtip.. on my RV-8 kit, it gets mounted to the right aileron bellcrank bracket. The pitch servo goes in the fuselage at the bellcrank there. Why do you want to make up your own brackets and get creative when these other locations and brackets are available already?
Yeah—great point...model would help. It’s a flying RV6A. The current servo (step motor) is wingtip mounted. So I wouldn’t be getting creative, rather using the bracket in place vs using the Garmin bracket that is built for the GSA 28 and adding a bracket under the passenger seat.

I would reuse that wingtip location if there is no meaningful advantage to mounting it in the fuselage as is the “norm.” If there is an advantage, I’d do the better way.
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  #4  
Old 02-24-2021, 01:54 PM
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Laird Laird is offline
 
Join Date: Feb 2007
Location: SoCal
Posts: 79
Default Leave it in the tip....

For some history, when low cost AP's started showing up on the market (TruTrak for one), there were no "already available" mounts for them. On RV's that were already finished, it was easier to retrofit a servo mount in the wing tip and run a pushrod to the bellcrank instead of trying to shoehorn a servo thru the inspection plate. Same with mounting under the seat pan.

So a lot of us mounted it in the wing and it works fine. Maybe a couple of ounces more for the pushrod weight, but not much. Some 1800 hours later it's still working out fine for my RV6.

If you a servo already mounted in the wing, it's probably easiest to replace it there (easy access and your wires are already there).

I don't see a reason to try to mount it somewhere else at this point.

Laird
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  #5  
Old 02-25-2021, 06:59 AM
Scott Hersha Scott Hersha is offline
 
Join Date: Jan 2005
Location: Cincinnati, OH
Posts: 1,796
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I can’t see any reason not to put the new Servo in the wingtip, since everything is already there. You will only be swapping servos, and possibly run another wire or two (or not). The RV6 aileron bell crank is just like the one in the RV4, captured between two ribs, and had to be modified to make this work. That’s why the standard wing mounted bracket right next to the bell crank won’t work. See install instructions below (from Trio).

Click image for larger version

Name:	RV4-6_Servo_Wingtip_Install.pdf
Views:	42
Size:	1.79 MB
ID:	8735
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RV6/2001 built/sold 2005
RV8 Fastback/2008 built/sold 2015
RV4/bought 2016/sold/2017
RV8/2018 built/Sold(sadly)
RV4/bought 2019 Flying
Cincinnati, OH/KHAO
JAN2021
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