Rigging questions

deyoung

deyoung

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Chris
First, how much does it typically cost to re-rig a Cherokee, roughly?

Second, how do you know (in varying degrees) when you need it?

I'm pretty sure I do... I don't get quite as much speed as others with the same plane report, though only by a few knots, but still. Bigger clue---in smooth air when trimmed out for hands-off flying as close as I can get (which is really pretty close), the ball is not quite centered. If I adjust rudder trim until it is centered, the plane wants to roll slowly. More generally, it's pretty hard for me to find a rudder trim spot where it really "feels" right... obviously that's really subjective and could very well just be me, but it's still a thing.

Thanks!
 
Power off stall is a good start
 
James331 said:
Power off stall is a good start
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For what -- does it break more to one side or the other than I would expect? Or something else? No, it doesn't particularly break one way or the other, but Cherokees are pretty darn docile in stalls...
 
If it’s out of rig most planes in my limited experience will show it in a power off stall as well as hands off cruise
 
If you think it’s draggy or not flying true, take it to your mechanic and ask him to check it out.
 
Check the TC first and make sure the ball is centered when the airplane is parked on a level surface.
 
dmspilot said:
Check the TC first and make sure the ball is centered when the airplane is parked on a level surface.
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This.

As far as yours being a little slower than your peers, people sometimes fib about things like that. Maybe you are being honest with yourself.

Or there could be some plumbing issues with your pitot/static system that cause a slight decrease in indicated airspeed.
 
My 140 was the same when I got it. Made the tool and checked aileron and flap rigging per the maintenance manual. Ended up having to lower the right flap a bit to adjust for the heavy right wing.
 
Which wing is heavy? I always burn the left tank first because I'm normally solo and that makes the left wing heavy. I know my plane (also a Cherokee type) is properly rigged because I can tell my passenger's weight based on the aileron feel in level flight.
 
How much more speed do you really think you're going to get? It's a Cherokee for Odin's sake.
 
deyoung said:
First, how much does it typically cost to re-rig a Cherokee, roughly?

Second, how do you know (in varying degrees) when you need it?

I'm pretty sure I do... I don't get quite as much speed as others with the same plane report, though only by a few knots, but still. Bigger clue---in smooth air when trimmed out for hands-off flying as close as I can get (which is really pretty close), the ball is not quite centered. If I adjust rudder trim until it is centered, the plane wants to roll slowly. More generally, it's pretty hard for me to find a rudder trim spot where it really "feels" right... obviously that's really subjective and could very well just be me, but it's still a thing.

Thanks!
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Are you correcting your indicated air speed to true air speed? At seven thousand feet, you have a few more knots than would be showing on the airspeed indicator.
 
steingar said:
How much more speed do you really think you're going to get? It's a Cherokee for Odin's sake.
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That extra knot or two is more important in a Cherokee than it is in a Mooney. ;)

When I was a Cherokee owner I remember reading an article by the late Art Mattson about the importance rigging his Cherokee played in achieving the astounding performance he had. I think his STCs are now owned by these folks: http://planedynamix.azurewebsites.net/

One problem with the Pipers is they do not have an eccentric bushing on the rear wing attach, like Cessna, to adjust the angle of incidence of each wing.
 
We re-rigged my plane at the last annual. Pretty easy to follow the service manual when all the inspection panels are off. You'll need a cable tensiometer and lots of safety wire since all the turnbuckles will be loosened and then re-tightened. I also made an aileron holder using two 2x4 pieces and a long screw to hold the aileron straight while we tightened the cables. Once the plane was opened up and I had removed the wire and loosened the turnbuckles it took about two hours. The hardest part was removing and replacing the push-rods and adjusting them so they were even. Mine were off by about 1/2 inch. Probably done when the plane was painted.
 
I know from the Cirrus forum that on a Cirrus the wheel fairings installed at slightly the wrong angle can have a big effect on drag.

Not sure if there's any room to adjust the fairings on a Cherokee, but just something to consider.
 
steingar said:
How much more speed do you really think you're going to get? It's a Cherokee for Odin's sake.
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Well, yeah, it's not really about a couple of extra knots; it's more about I just want it to be right. :)
 
You aren't alone Chris. I had a heavy wing and got the rigging adjusted which fixed the heavy wing but now I have an issue at straight and level and hands off, my yoke is turned about 10 degrees to the right. Same as you, I tried rudder trim and it wants to roll over. My annual is in a couple days and I'm just going to have them break all the safety wire and re-rig the whole thing. Lots of Cherokee's out there that are out of rig or have problems staying IN rig.
 
Last year, I flew a 172N that had been owned and maintained by a couple of fussy old gents for a number of years. Compared to the newer R's and S's, it was so much lighter on the controls and so smooth and well balanced, I remarked to its new owner about it several times. He told me the previous owners had told him that the difference was in the replacement of the pulleys and associated hardware, as well as maintaining proper cable tension. I suspect that there's more than a few old Cherokees and Cessnas out there that could benefit from, not just "checking" the rigging, but going through it to replace worn hardware.
 
Timbeck2 said:
You aren't alone Chris. I had a heavy wing and got the rigging adjusted which fixed the heavy wing but now I have an issue at straight and level and hands off, my yoke is turned about 10 degrees to the right. Same as you, I tried rudder trim and it wants to roll over. My annual is in a couple days and I'm just going to have them break all the safety wire and re-rig the whole thing. Lots of Cherokee's out there that are out of rig or have problems staying IN rig.
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Mine too...both the heavy wing and/or slip without rudder trim, as well as down a few knots vs what the book says it should be. Common problem, but I can live with it.

Funny side note, I have a camera that mounts on the tail hook. I've noticed on the camera when the plane is rudder-trimmed to fly without a slip, my front wheel pant is turned to the right probably 10 degrees...that's a LOT of trim to keep it straight.
 
Yesterday I fixed a slightly heavy right wing on the RV with some model-plane tech...a piece of balsa trailing edge stock, 1" x 6". Coated it with epoxy, attached it to the underside of left aileron with servo tape, and then added some foil tape to smooth the leading edge transition. A little touch up paint for good measure.

I think later, I'll take the tape off and make a dry micro fillet along the leading edge, and then sheet the whole thing with foil tape for a more finished appearance.

So nice to have the trim neutral...shoulda done this sooner. Before, when I flew solo I had enough adjustment to trim it out, but with pax I'd always have to exert a small amount of stick side pressure. I was pretty luck to guess the correct width of the wedge on the first try.

I like having a little bit of model plane in the full size one. :D

IMG_3229.jpg
 
SoCal RV Flyer said:
Yesterday I fixed a slightly heavy right wing on the RV with some model-plane tech...a piece of balsa trailing edge stock, 1" x 6". Coated it with epoxy, attached it to the underside of left aileron with servo tape, and then added some foil tape to smooth the leading edge transition. A little touch up paint for good measure.

I think later, I'll take the tape off and make a dry micro fillet along the leading edge, and then sheet the whole thing with foil tape for a more finished appearance.

So nice to have the trim neutral...shoulda done this sooner. Before, when I flew solo I had enough adjustment to trim it out, but with pax I'd always have to exert a small amount of stick side pressure. I was pretty luck to guess the correct width of the wedge on the first try.

I like having a little bit of model plane in the full size one. :D
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Did you try following Vans Heavy Wing recommendations first?
 
Ray Eaker said:
Did you try following Vans Heavy Wing recommendations first?
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Yeah, checked all the usual suspects. Can't squeeze the aileron trailing edge to fine-tune on a -9 because the skin rivets to the AEX wedge; it's not a folded aluminum edge like on a -7. Wing incidence is not adjustable, but I triple-checked incidence before I drilled the holes in the rear spar, locking it in.

Very happy with the mod!! It looks enormous in the zoomed-in photo--smaller in real life and hardly noticeable since it's on the underside.
 
wilkersk said:
Last year, I flew a 172N that had been owned and maintained by a couple of fussy old gents for a number of years. Compared to the newer R's and S's, it was so much lighter on the controls and so smooth and well balanced, I remarked to its new owner about it several times. He told me the previous owners had told him that the difference was in the replacement of the pulleys and associated hardware, as well as maintaining proper cable tension. I suspect that there's more than a few old Cherokees and Cessnas out there that could benefit from, not just "checking" the rigging, but going through it to replace worn hardware.
Click to expand...

Yup. I long ago lost count of the times I have found seized pulleys and cable tensions way out of spec. That's what you get for a $500 annual. A drop or two of Royco 363 on a pulley bearing every few years can save a ton of money; it doesn't seize and get cut up by the cable, and the cable doesn't get abraded and start fraying.
 
Timbeck2 said:
You aren't alone Chris. I had a heavy wing and got the rigging adjusted which fixed the heavy wing but now I have an issue at straight and level and hands off, my yoke is turned about 10 degrees to the right. Same as you, I tried rudder trim and it wants to roll over. My annual is in a couple days and I'm just going to have them break all the safety wire and re-rig the whole thing. Lots of Cherokee's out there that are out of rig or have problems staying IN rig.
Click to expand...

They probably tried to fix the heavy wing by adjusting the ailerons. It does not work. Not one bit. Ever. Rigging one aileron down just results in it pushing up against the cables, which pulls the other aileron down so that now they're both down a bit and the wheel is now canted. I don't understand why mechanics can't figure that out. The only airplane where it would work is in an airplane with an aileron-centering device like the Cirrus uses, and the Cirrus has aileron trim that just moves the centering as necessary.

The only other option is an aileron trim tab, and there are multiple issues with that. Legality of modification, mass balance and flutter, and so on.
 
Thanks for that Dan. I wasn't there when my heavy wing was "fixed" so I don't know. I DO know however that it was an IA that did it and a well respected one at that. That very may well be the case of how he fixed it but it doesn't explain how its getting worse.
 
deyoung said:
First, how much does it typically cost to re-rig a Cherokee, roughly?

Second, how do you know (in varying degrees) when you need it?

I'm pretty sure I do... I don't get quite as much speed as others with the same plane report, though only by a few knots, but still. Bigger clue---in smooth air when trimmed out for hands-off flying as close as I can get (which is really pretty close), the ball is not quite centered. If I adjust rudder trim until it is centered, the plane wants to roll slowly. More generally, it's pretty hard for me to find a rudder trim spot where it really "feels" right... obviously that's really subjective and could very well just be me, but it's still a thing.

Thanks!
Click to expand...
deyoung said:
First, how much does it typically cost to re-rig a Cherokee, roughly?

Second, how do you know (in varying degrees) when you need it?

I'm pretty sure I do... I don't get quite as much speed as others with the same plane report, though only by a few knots, but still. Bigger clue---in smooth air when trimmed out for hands-off flying as close as I can get (which is really pretty close), the ball is not quite centered. If I adjust rudder trim until it is centered, the plane wants to roll slowly. More generally, it's pretty hard for me to find a rudder trim spot where it really "feels" right... obviously that's really subjective and could very well just be me, but it's still a thing.

Thanks!
Click to expand...
deyoung
One fellow said to check the ball on a level surface. Good idea. I tried that and had to use a different approach. Lift up the back seat. Lay a long level on the main spar. Jack the wings until the level shows level, then check the ball. When I did this, I found that the instrument needed to be adjusted. That's an easy place to start.
 
Lots of good advice here for sure. Lots of information in the maintenance manual too. As for advice, figure out how many turnbuckle retainers you'll need instead of safety wire. It's so much faster. I think they're all -1's.
 
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