Auto Pilot

[moving2time]

Reading through the rudder discussions on the Rudder Bungee thread got me thinking. How would you install the auto pilot servos on a Highlander that are necessary to operate an Auto Pilot system? The aileron and elevator are both push pull systems but the rudder is only pull pull. Seems I remember people on this forum that have installed an Auto Pilot system on a Highlander so how do you connect the rudder on the Highlander to a servo? Am I missing something? I currently fly a CTLS, and it has a Auto Pilot system, but it's rudder does not have slack in it like the Highlander. The auto pilot is a great accessory when flying. It so nice to be able to spend all my time sight seeing the landscape below, I mean, scan the area for traffic! OOPS.

[sonex293]

The experimental's I have flow and the one I built only had servos on the Elevator and Ailerons. The Rudder was trimmed, such that in a normal cruise flight you could fly with your feet off the pedals, but during climbs or other power setting, the Pilot was the Rudder Auto Pilot. I'm looking to add Pitch and Roll servos to my Highlander build. If anyone has ANY pictures of AP installations in the Highlander, SuperSTOL, or Escapade, please post them!

==
Michael

[danerazz]

I'd venture to say MOST general aviation autopilots are 2-axis (pitch/roll only) with some only being roll, you trim the pitch to hold altitude and the autopilot just turns/levels the wings.

I think an autopilot on a highlander defeats the purpose of the plane, but I guess I could see some use to it. The ailerons would need a capstain servo.

[BRS]

Highlander pitch servo installation.

Instead of starting a new thread, this one seems like a good place to post this. I'll try to get some shots of the roll server and post that info here later.

Pitch servo, here are some pictures of my pitch servo installation. I got the generic install kit. Swapped one of the heim joints to a 1/4 bore X 1/4-28 thread and just used a longer bolt on the elevator side of the mixer. I cut about 1/2" off the linkage tube then tapped both ends to 1/4-28. It worked out that using the last hole on the short arm that the arm travel was just about 5˚ (on each side) shy of the 60/60 safety limiter.

Performance: out of the box with no adjustments to the skyview (software 11.x) the autopilot captures and holds altitude to within +- 10˚. I'm very happy with this. Note worthy is that on the ground the highlander elevator is heavy and the servo can't hold it up, in flight this is not an issue at all. So just remember to help it a bit on the stick while doing the initial calibration.

Changes, I might change how the mounting plate holds the tubing though what I have now seems quite secure. I'm open to ideas. Also I'll probably install some sort of tether on the servo side of the linkage arm up to the push tube. I can't imagine this linkage failing but if it were it could fall down in front of the servo making up elevator problematic.

[kenryan]

Here's how I mounted my elevator servo. It allows full control deflection when attached to the middle hole on the servo arm. It seems it will work good, but hasn't been tested.

Elevator Servo 1

Elevator Servo 2

Elevator Servo 3

[kenryan]

Here's how I mounted my aileron servo (before safety wiring). I added an extra aileron pulley so the servo cable can loop back and connect to the control cable right where it exits the doghouse. It seems like it will work good, but hasn't been tested.

Aileron Servo 1

Aileron Servo 2

Aileron Servo 3

[sonex293]

Thanks guys for all the pictures. The pitch installation was exactly how I thought it would be, very similar to a previous airplane installation. Thanks Ken for the Aileron (Roll) servo installation. Anyone have other Roll Servo Installation methods and/or pictures?

==
Michael

[danerazz]

I was considering installing one and was planning on putting it under the turtledeck with a capstan servo on the interconnect cable. Never did it so can't say how it would have worked, but that was my plan.

[dennis123]

I was considering installing one and was planning on putting it under the turtledeck with a capstan servo on the interconnect cable. Never did it so can't say how it would have worked, but that was my plan.

i would recommend you to take advise from those who had already installed this then try this. here people can give you there remarks and may be that can help you out

[sonex293]

Bringing back this topic too see if there's been any new installs recently? The devil is in the details.

My build partner and I are at the point right before covering the fuselage and trying to get those things done that would be easier to do before covering. The Pitch servo install seems pretty straight forward. We can either mount the servo under the seat and tie into the control stick or mount it behind the baggage area and tie into the bellcrank. We'll probably do the bellcrank method. More room back there, but definitely needs to be done before covering.

The roll servo is another beast. We've got a servo with the Capstan kit and trying to decide on servo location and how to tie into the control cables. Two options: Under the seat or under the turtledeck. Connecting into the cabling under the turtledeck looks like it could be a nice clean install, no extra pulleys required, and fewer restrictions. One drawback I see in this install is that there is less cable movement (if I remember my aileron cable attach bracket correctly). Does that matter? We've also played around with the placement under the seat. Making sure the cables don't rub any cross members or violate any pulley/capstan angle restrictions is quite difficult.

BRS and KENRYAN, how's your autopilots installs working out?

Anyone have any new pictures/recommendations?

==
Michael

[kenryan]

Michael, I'm still not flying so no test reports. Regarding the roll servo, I mounted it under the control stick assembly. My original plan was to run the servo cable to a pulley mounted under the aileron pulley and then back to the stick, making the connection in the area between the stick and the pulley. It works that way, but I didn't like having that cable clamp in the short section of cable between the stick and the pulley (if it moves it could easily jam the control) so I am going around the pulley the opposite direction and connecting in the cable run alongside the seat. This necessitates a couple of fairleads to guide the cable from the capstan to the pulley. I have not finished fabricating those fairleads so I don't have pictures of the final solution. Attached are a couple of pictures showing the current state of affairs.

[sonex293]

Ken,

Where did you get your Bridle clamps? Looks like they are a plastic/teflon material with two bolts and large washers. I've asked Garmin about them and the only way to get them from Garmin is to order a RV-10 Rudder servo kit and throw away most of the kit. I'm trying to make some using two aluminum plates, but that hole for a 1/16" cable is damn small. I've broke two #53 drill bits.

Any info you can provide on the bridle cable clamps would be appreciated.

--
Michael

[kenryan]

Michael, they came from Dynon. They are designed for 1/16 and 1/8 (rather than the 3/32 we have). Don't kick yourself for having problems making the clamps. Because they don't fit (1/8 v 3/32) I tried making some myself, and failed. Then I went to a machine shop, they too failed. (They said they didn't really have the proper tooling, but tried anyway.) What I am going to try next is to sand them down (or maybe scrape them) just enough so they grab the 3/32. I have already confirmed that if I wrap a tiny piece of silicone tape around the 3/32 it works really well, but it would be hard to adjust them with that tape in there, which is why I'm going to try sanding them. I have confirmed with Dynon that they have replacements if I screw something up. What would probably work would be to put a piece of heat shrink at the proper location on your 3/32 control cable. Unfortunately my cables are already made, so I can't do that. I'm pretty sure sanding them lightly is going to work. Just haven't gotten to it yet.

[danerazz]

Something like that should be made in two halves that sandwich the cable, and instead of drilling the recesses for the cable they should be milled with a fine or “V” milling bit. Obviously alignment is important but I cannot believe a machine shop couldn’t do it, unless they usually only work with large items and don’t have fine milking equipment.

A dremel milling setup jury rigged should accomplish a one-off. Or two flat plates with a spacer instead of grooves

[sonex293]

Dane,

I'm doing that right now but with a ball-nose bit. I'm cutting the two grooves into a long piece of aluminum and then I'll cut them to the required length once they are done. I've got the 1/16" groove milled and I'm waiting on the 3/32" bit to arrive tomorrow. Takes time due to the extremely small bit sizes, but the 1/16" groove came out very nice. I almost forget I had the mini-mill in the back of the workshop I use it so seldomly. Definitely the right tool for the job.

==
Michael