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How? Dynon Autopilot Install on RV-3A

I used the standard Dynon wing mount kit for the roll axis, and made my own pitch servo mount. For connecting to the pitch bellcrank, I used Dynon's generic mount kit.

Here's the pitch servo. I don't seem to have a photo of the roll servo installation but it's fairly stock.

ZR6CD0w.jpg


Here's a view of the pitch brackets.

PrC6jRJ.jpg


With the roll servo, at first I installed GRT's servo and later replaced it with Dynon's. The Dynon one was easier to attach because the GRT one had a connector in a very awkward position. But the Dynon one did need a small bracket, supplied in their kit, for more rigidity, if I remember right. The wings are out at the hangar and I can't get there today for a photo.

Bottom line, I think that the 4/8 pitch kit and the 7/8/9 roll kits will work. Or you could assemble your own.

Dave
 
The 0.75" dimension confirmed by Dynon.

The bottom holes in the angles of course have to be made to work with the RV-3 fuselage bulkheads.

Finn
 

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As Dave has said the pitch kit for the 4 & 8 works well and is straight forward to fit. I used the roll servo kit for the 7,8 & 9 and apart from a length adjustment to a support bracket it works well. However this is for the 3B wing and as the servo mount bracket replaces one of the bellcrank brackets this could be different for your RV 3A.
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I have a Dynon EFIS-10A....

I'm more fascinated to learn how you got that EFIS between the instrument panel and the fuselage fuel tank. I was looking at doing that recently, but there was just no way it would fit in my plane. Colour me curious...
 
I'm more fascinated to learn how you got that EFIS between the instrument panel and the fuselage fuel tank. I was looking at doing that recently, but there was just no way it would fit in my plane. Colour me curious...

My 3A has wing tanks. It doesn't have a fuselage tank.
 
I used the standard Dynon wing mount kit for the roll axis, and made my own pitch servo mount. For connecting to the pitch bellcrank, I used Dynon's generic mount kit.

Here's the pitch servo. I don't seem to have a photo of the roll servo installation but it's fairly stock.

ZR6CD0w.jpg


Here's a view of the pitch brackets.

PrC6jRJ.jpg


With the roll servo, at first I installed GRT's servo and later replaced it with Dynon's. The Dynon one was easier to attach because the GRT one had a connector in a very awkward position. But the Dynon one did need a small bracket, supplied in their kit, for more rigidity, if I remember right. The wings are out at the hangar and I can't get there today for a photo.

Bottom line, I think that the 4/8 pitch kit and the 7/8/9 roll kits will work. Or you could assemble your own.

Dave

Perfect, here's my order for people who search for this in the future:
Autopilot Order
2 x SV32 standard arms
4/8 Pitch Kit - Install Instructions
RV-7/8/10 Roll Kit - Install Instructions
2 x Network Autopilot Servo Cable Kit

Hopefully that works.

Is the AP74 worth the extra $450 or does it work fine through the EFIS?

Thanks!
 
I too have a question about mounting an autopilot servo. Has anyone mounted the roll servo in the space just below your knee, near the stick? I was having questions as to whether I wanted to mount it in the wing and it not being easily serviceable. I have a trutrak ADI pilot II.
 
I too have a question about mounting an autopilot servo. Has anyone mounted the roll servo in the space just below your knee, near the stick? I was having questions as to whether I wanted to mount it in the wing and it not being easily serviceable. I have a trutrak ADI pilot II.

I think you’d find “under the knee” to be really constraining when it comes to shifting positions in flight. I often pull my heels back and get my knees up towards my chin to change seating positions on a long flight leg. If you clutter up that floor area, you won’t be able to do this, and the cockpit will be pretty tight.

Because of the geometry of the cockpit in my little jet, I really don’t have any alternate positions available (it makes the RV-3 feel spacious) - but I’m a glider in two hours due to fuel capacity, so most flight legs are only a touch over an hour anyway, so it doesn’t make any difference.

Paul
 
I think you’d find “under the knee” to be really constraining when it comes to shifting positions in flight. I often pull my heels back and get my knees up towards my chin to change seating positions on a long flight leg. If you clutter up that floor area, you won’t be able to do this, and the cockpit will be pretty tight.

Because of the geometry of the cockpit in my little jet, I really don’t have any alternate positions available (it makes the RV-3 feel spacious) - but I’m a glider in two hours due to fuel capacity, so most flight legs are only a touch over an hour anyway, so it doesn’t make any difference.

Paul

All good points, thank you. I am on the fence about an autopilot. I am VFR only, mostly a flagpole flyer and local formation flights. I can count on one and a half hands how many times I took my -4 or Rocket on a cross country, and only my Rocket had an autopilot...but I admit, it was very nice on that 3 hour flight to Idaho. My thoughts were that if I could put it down below my knee, I could add it later if I wanted to. My -3 is very bare bones.
 
I can fly my 3 on the manual elevator trim (useful when you are using your stick hand) and as I have relatively stiff ailerons it pretty much flies itself.
 
How to mount

So I got the brackets and the kits. But the belcrank is completely different. I can’t figure out how to mount the servo. Anyone do this before?
 

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Next time I'm at the airport, I'll try to measure the radius from the pivot to the pushrod attachment point for you. Mine is the RV-3B installation very much like Russell's. Perhaps using the same dimension might work for you.

And maybe someone with closer access to their wings might beat me to it.

Dave
 
So this is what I'm thinking. I'll get a piece of 1x1.5 aluminum angle and bolt it or epoxy it to the cross rib. Then I will mount the servo on that.

I don't know how easy it will be to get a drill in there to make a hole. Is epoxy sufficient? Anything I need to consider?

I'm not a builder at all.
 

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I need to replace these brackets for the pitch servo. These are riveted on with looks like two rivets. I don’t know how to rivet. Can I just put a bolt and nut on?
 

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Hello Derek,

Just looking at your last two posts on both servo mounts, I’d urge you to find a local builder to have a close look and talk it over with. First, forget about the epoxy for mounting anything to the structure - there is no way to be certain that you have a good bond, and it will work great until it pops off completely, all at once.

Second, the thought of substituting bolts for rivets sounds Ok until you start considering what is called “edge distance” - the distance the hole is from the edge of the sheet/part. that is generally going to be twice the diameter of the hole, and that is hard to achieve with a bolt that is going to be at least 3/16”.

Looking at the way the mounts for the pitch bellcrank are installed right now concerns me - it’s got two rivets that appear really close together - that sort of makes Swiss cheese out of the flange to which the angle is attached. When you drill those out there is no place to drill an additional hole and maintain any kind of integrity to the part, and the pitch bellcrank is REALLY important to safe flight! So there is going to have to be some repair work done there, and its going to take an experienced eye and some knowledge of acceptable repair techniques to solve. It’s solvable - just will take some thinking.

So....I urge you to get some on-the-spot experience to look over the design aspects with you. It’s pretty hard to to this well by remote conversations on the internet.

Paul
 
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I'll be seeing the plane in a few days - Derek is not far from me, and I can probably assist with repairs and installation of the pitch servo.

Dave
 
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Hello Derek,

Just looking at your last two posts on both servo mounts, I’d urge you to find a local builder to have a close look and talk it over with. First, forget about the epoxy for mounting anything to teh structure - there is no way to be certain that you have a good bond, and it will work great until it pops off completely, all at once.

Second, the thought of substituting bolts for rivets sounds Ok until you start considering what is called “edge distance” - the distance the hole is from the edge of the sheet/part. that is generally going to be twice the diameter of the hole, and that is hard to achieve with a bolt that is going to be any least 3/16”.

Looking at the easy the mounts for the pitch bellcrank are installed right now concerns me - it’s got two rivets that appear really close together - that sort of makes Swiss cheese out of the flange to which the angle is attached. When you drill those out there is no place to drill an additional hole and maintain any kind of integrity to the part, and the pitch bellcrank is REALLY important to safe flight! So there is going to have to be some repair work done there, and its going to take an experienced eye and some knowledge of acceptable repair techniques to solve. It’s solvable - just will take some thinking.

So....I urge you to get some on-the-spot experience to look over the design aspects with you. It’s pretty hard to to this well by remote conversations on the internet.

Paul

Got it! I need to not wing it.

Dave is coming to the rescue!
 
You might seriously think about mounting the roll servo in the wingtip. The bellcrank setup on the RV3 is different than the later models I believe from pictures I have seen and there is just no room in there for hands either to work with that rib in the way. I'm sure David will get you squared away with the pitch wig wag mount. Those rivets are kinda scary, should have bolts or at least screws there. Also if you make longer wig wag mount angles you can use them to mount your pitch servo also.
 
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