Highlander Aileron Rigging (adverse yaw)

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Highlander Aileron Rigging (adverse yaw)

Postby BRS » Mon Oct 06, 2014 1:28 am

I've been working on an issue with my Dynon roll servo which made me think that reducing adverse yaw might finally get this unit to stop over shooting while tracking. My wing is a bit longer than the standard Highlander wing so I might have more adverse yaw than the rest of you folks. So anyway here is my question...

The build manual shows the rigging to be equal up and down aileron. A common method for reducing adverse yaw is to make the aileron travel up more than down as the down creates more drag and is on the outside of the turn trying to pull the nose right when you bank left (visa versa). Has anyone tried rigging so that the ailerons move up more than down? This could be done simply by adjusting the cable lengths. The obvious downside would be that in their neutral position they would be slightly up and not in line with the retracted flaps.

Any experience with this out there?

Thnx
-brs
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Re: Highlander Aileron Rigging (adverse yaw)

Postby moving2time » Mon Oct 06, 2014 9:45 am

I can't comment on your adverse yaw question but I would like to know why and how your wing is longer than the standard Highlander?
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Re: Highlander Aileron Rigging (adverse yaw)

Postby BRS » Mon Oct 06, 2014 11:49 am

Long wing:

The original builder (Steve H.) wanted longer flaps so he added one more bay (rib) to the end of the wing and moved every thing out.

So, since I have a non standard wing, and it's the only Highlander I've flown, can some folks pip-in about how much adverse yaw you have?
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Re: Highlander Aileron Rigging (adverse yaw)

Postby SheepdogRD » Mon Oct 06, 2014 3:54 pm

I remember Steve writing about the changes he made to the wing, but I thought he lengthened the flaps one bay and shortened the ailerons by the same amount, leaving the wing standard length. As I remember, he also changed the tips. Perhaps I'm thinking of a different plane...
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Re: Highlander Aileron Rigging (adverse yaw)

Postby moving2time » Thu Oct 09, 2014 9:51 am

I have been collecting photos of as many completed Highlanders and SS's as I can find so I went through all four He Haw's and it looks like the plane in question is #2. The flaps were definitely extended out to the strut attachment point but none of the photos I have colected show the entire wing in such a way to allow me to determine if it has been extended. Steve is all about the weight to power differential and If the wing was extended then he would have had to build the wing from scratch including making up the tubes from scratch. I would be surprised if he extended the wing mostly because of the weight it would add as well as the work it would take to build the new tube spars from scratch. Extending the wing would also add a lot of drag to the Highlander which would be detrimental to it's performance. I would be surprised. Joe B
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Re: Highlander Aileron Rigging (adverse yaw)

Postby SheepdogRD » Thu Oct 09, 2014 11:13 am

Here's N642SC in a picture from Steve's website, http://www.wildwestaircraft.com. It shows extended flaps, but the aileron cable is in the standard position.
N642SC-1.jpg

This picture shows the "splates" on the wingtips:
N642SC-2.jpg

I'd bet Steve can clear this up for us...
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Re: Highlander Aileron Rigging (adverse yaw)

Postby danerazz » Thu Oct 09, 2014 11:33 am

Can you just measure your span, or even easier, count ribs? 7 ribs outside the fuel tank including tip rib, plus one each side of tank for 9 total if it is normal length, or maybe Steve will chime in with the info straight from the horse's mouth (don't mean to throw you under the bus here, Steve).
Dane

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Solved (adverse yaw)

Postby BRS » Sat Oct 11, 2014 2:08 pm

This thread was about Adverse Yaw not so much about the fact that the wing was extended.
As of yesterday the adverse yaw has been solved and now the autopilot is tracking smoothly. Here is what I discovered and did. The solution was quite simple.

First I had to call the factory to figure out where the ailerons were supposed to be rigged. They first told me to line them up with the wing tips. Oh, that's easy I thought, then I remembered I don't have wing "tips" but wing "splates" (see earlier pics). So then they told me how to do it with a straight edge on the trailing edge of the wing. Upon laying a straight edge on the aft flat spot of the wing it was very clear the ailerons were rigged to droop. They were also noticably lower than the retracted flaps. Then I seemed to remember Steve saying something about this for added STOL capability (or perhaps I dreamed that he said this). I guess I could just ask him. If you are reading this, Steve, feel free to say hello.

So the solution was to readjust the turnbuckles. I managed to bring the ailerons up by 3˚ and now they line up with the retracted flaps. Whats more, the adverse yaw has almost disappeared and the autopilot is quite happy.

For reference, I zeroed my digital level to the small cross tube near the wing attach points for the wing strut. Then I layed it against the bottom of the aileron. The angular difference is now 3.1˚ where as it was 6.4˚ before. Thanks for all your input.
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Re: Highlander Aileron Rigging (adverse yaw)

Postby kenryan » Sat Oct 11, 2014 2:20 pm

Is your roll servo SV-32? Do you have elevator servo, too? If so, is it also SV-32?
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Re: Highlander Aileron Rigging (adverse yaw)

Postby BRS » Sun Oct 12, 2014 12:50 am

Is your roll servo SV-32? Do you have elevator servo, too? If so, is it also SV-32?


Yes they are both SV32. The aileron forces are quite light on this plane I have the Roll force at 50%. Steve H installed the roll servo and did a great job.

I installed the pitch servo two weeks ago. It can't hold up the elevator while on the ground as there is no air holding it up but in flight it works great.

I can upload some pictures on an appropriate thread if you like.
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Re: Highlander Aileron Rigging (adverse yaw)

Postby kenryan » Sun Oct 12, 2014 10:27 am

Yes I would love to see how the servos are mounted.
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Re: Highlander Aileron Rigging (adverse yaw)

Postby BRS » Sun Oct 12, 2014 1:08 pm

kenryan wrote:Yes I would love to see how the servos are mounted.


Here you go. I've put the info an a thread about autopilots.

viewtopic.php?f=218&t=23196&p=46081#p46081
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Re: Highlander Aileron Rigging (adverse yaw)

Postby taildrgfun » Tue Oct 14, 2014 2:10 pm

I was gone to a fly in in Nevada the last few days and just noticed this thread this morning when Jac mentioned it to me.
I did make the wing on that Highlander 10 inches longer than normal and then put a flat wingtip or splate on the end of it. I wanted more wing area so the airplane would fly and land slower which is also why I made the flaps 18 inches longer towards the outside and about 4 or 5 inches longer towards the inside. The inside pieces are removable so that the wings can still be folded. This also allowed me to have more aileron on the outboard end to help make up for some of the aileron that I took away from the flap end of it. I was extremely happy with the way it all worked out.

I am pretty sure I had the flaps set up so that they would go up more than the normal position for more cruise speed but I did not have the ailerons set up that high because slow landing was my number one priority. Brock I am glad you got it set up to better suit you and how you like to fly and use the autopilot.
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