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Trio Avionics Roll Servo location

M

Mustang

Well Known Member
Guys and gals,

We are presently installing the aileron controls in the left wing and I thought that mounting the autopilot roll servo in this wing might be a good idea. We were looking for locations for the servo and thought that the second inspection panel out from the root might be a good spot.

Then I got reading the Trio installation manual, and they talked about clamping the servo actuator rod to a section of the control system that had NO ROTATION in it's travel.. We manually rolled the main (big) tube to the aileron bellcrank and it rocked back and forth. Hmmmmm. Maybe no good?? Then I thought, "What about when the pushrod tube is connected to the torque tube under the stick, would it still rock then?" The other bearing is oriented in the vertical plane and the bellcrank bearing in the horizontal plane. Of course we cannot hook the pushrod tubing up to the stick/torque tube because the fuselage is in the hangar and has nothing in it anyway.

Can anybody answer this question or does anybody have experience in mounting the servo out in the wing, and how did you do it.

Cheers, and thanks,
Pete
 
I mounted mine just outboard of the bell crank. I used some extra z brackets so I could easily remove it. It will come out the access place. I mounted mine to the spar web, using z brackets and platenuts in the spar web. Push rod is connected to the bell crank.

Works. This method has been successfully used in the roll servo installations for many years.

Oh and you will Love the Trio
Good luck
 
aileron servo mounting

Then I got reading the Trio installation manual, and they talked about clamping the servo actuator rod to a section of the control system that had NO ROTATION in it's travel..
Click to expand...

The clamp is used on various "Rutan-type" planes and not RV's. You need to connect the servo pushrod directly to the aileron bellcrank using the supplied hardware. The servo can be either mounted in the wing close to the bellcrank or out on the tip rib with a longer pushrod to the bellcrank.

Here is detail about a wing-tip mount:

http://thervjournal.com/navaid.html

There is a photo in the article that shows the pushrod connected to the bellcrank.

Sam Buchanan
 
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I was speaking to Chuck at Trio about this just a couple of days ago. In general they recommend a wing installation, either at the bellcrank or at the wing end. This is because the motion is completely linear at this point, and the servo push rod can connect directly to the bellcrank using the same bolt as the main pushrod. I used the SafeAir1 installation kit in the last bay of the wing and it went in perfectly. On an RV-8, an installation like Mickey's is fine although there are issues doing this in a side by side aircraft like the 6 or 7.

The main thing to remember is that the aileron should hit its stops before the servo its its stops. Also, the longer the arm on the servo, the better (within limits of course) as you get more torque with a longer arm. It is best to try to match the pivot to push rod distance on both the bellcrank and the servo control arm, if possible.

For a simple installation, go with the SafeAir1 kit. Trio thinks it is a good installation, and the SafeAir1 guys are great to deal with.
 
Any Pics or instruction sheet for SafeAir?

Can any one post a picture of the SafeAir Servo installation Kit, of can some one scan the instruction sheet and email it to me. Thanks George [email protected]
 
Here're some pics of my install. Tony at SafeAir1 is terific; I'm sure he'll send you the install manual if you give him a shout. The kit contains a premade pushrod, a mounting plate cut 'n bent to fit the spar web and clear the flange, and necessary hardware -- quick 'n easy!

 
Thanks Alan

Alan Erickson said:
Here're some pics of my install. Tony at SafeAir1 is terrific; I'm sure he'll send you the install manual if you give him a shout. The kit contains a premade push rod, a mounting plate cut 'n bent to fit the spar web and clear the flange, and necessary hardware -- quick 'n easy!
Click to expand...
That is all I need. I wounder why they go several bays out. Is that for wing tip access? George
 
George,


SafeAir1 designed the kit so it could be installed in a completed aircraft through the wing tip. Although I installed mine when the wing was under construction, you can do so through the lightning holes in the outboard rib without any problem.
 
Guys,
Thanks for the great write-ups and photos. I've got lots to work with. Now I gotta make a decision!

Cheers, Pete
 
I wonder how one would get the wiring through the wings on a completed airplane if you don't have conduit through there. All I have is snap bushings, and they have wires in them already. Any ideas?
 
I wonder how one would get the wiring through the wings on a completed airplane if you don't have conduit through there. All I have is snap bushings, and they have wires in them already. Any ideas?
Click to expand...


Paul, if you can remove the wing-tip, you can add a lightweight PVC conduit by running it through the lightning holes. The new conduit can be secured at the ends and at mid-span (work through the inspection hole) with whatever means you deem necessary (nylon ties, some sort of bracket pop-riveted to the ribs, etc, etc, ...). Obviously, it is important to make sure the conduit is secure and can't interfere with the aileron pushrods. I used this method to add a conduit for the LRI probe plumbing since the original conduit was too full of lighting and autopilot wires.
 
Gotcha Sam. I guess I'll secure it in 3 places. Wing tip, inspection cover, and wing root. I'll pull the wingtip (thank goodness it is screwed on) next week and see.
 
Another method is to use one of the existing wire to pull a drag line through the conduit. The pull that wire and a new one back with the drag.
 
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