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Looking for a Scott 1302 Rudder Arm for my new old airplane

RVBottomly

PATRON
Asotin County Washington (KLWS)
I ended up buying the [FONT=Verdana,Arial,Tahoma,Calibri,Geneva,sans-serif]Commonwealth SkyRanger 185 I had been looking at for six months. It flies like a dream, climbs better than expected, and is all around fun.

Except for one thing: she is squirrely in the extreme on pavement while taxiing. No problem with landing, but once you rely on tailwheel steering she is slow to respond, and then jerks.

I'm pretty sure I know why. The rudder arm does not extend down far enough and the springs to the tailwheel are on a sharp angle.

tail-wheel-rotated.jpg

The drawing shows it like this:

tailwheel-drawing-16-146.jpg

See how the tailwheel springs are below the leaf spring instead of up at the sharp angle.

Drawing specifies a Scott arm 1302-1. I can't find one in my online search. Does anyone know where one might be found? I suppose I could build one if necessary.
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Another consideration might be a leaf spring with less arch or just longer to get the tail wheel further back providing you with a better steering setup.
 
Another consideration might be a leaf spring with less arch or just longer to get the tail wheel further back providing you with a better steering setup.

Good point. The tailwheel on there now is a Maule. The original is a Scott 2000. It does look like the leaf spring is a bit aggressive.
 
I looking at the image zoomed in a bit, I prefer to have the TW pivot as vertical as possible so the plane is not trying to "fall off" to either side. You probably have no spring shops that can bend springs to your drawings near by but a set of springs made for that plane will tame it down considerably.
 
I looking at the image zoomed in a bit, I prefer to have the TW pivot as vertical as possible so the plane is not trying to "fall off" to either side. You probably have no spring shops that can bend springs to your drawings near by but a set of springs made for that plane will tame it down considerably.

Thanks for the idea. We have a custom 4x4 shop that might be able to help. I've seen some pretty amazing suspensions come out of his shop.
 
steering arm play

Another question: how much play is normal on the tailwheel arm?

Here's a video of what I have:

 
My belief is there should be "little to no" free play inside the TW. But is is not uncommon to see the amount you have.

My opinion, Or lets say, If it were mine,

I would find a shop that can De-arch that spring so the caster is proper.

Disassemble the TW to see in there are any worn parts, "there might not be any"
But due to the excess arch in the spring that TW is probably beating itself to death.

Is there any freeplay at the rudder arm?
 
Resurrecting this old thread with an update.

I found a rudder arm that is an exact match to the drawings. Also decided to replace the Maule tailwheel with a replica replacement to the Scott 2000 tailwheel.

The airplane is in annual right now, and I'm having a few other things fixed up. One thing my IA does not like is the tail spring. Apparently someone in the past ground down the sides to get it to fit the 1.25 fitting for the Maule assembly. Also, as pointed out by CharlieN, the bend is too sharp.

So now I'm looking for a tail spring that matches the 14-057 in the drawing above. I'd go with trying to rebend, but grinding on the spring means I can't use it.

So it goes. We might make a Champ spring work.
 
Vic

Like Charlie referenced in #4 try to keep the pivot point vertical. Not only for ease in handling but to prevent shimmy.
 
Resurrecting this old thread with an update.

I found a rudder arm that is an exact match to the drawings. Also decided to replace the Maule tailwheel with a replica replacement to the Scott 2000 tailwheel.

The airplane is in annual right now, and I'm having a few other things fixed up. One thing my IA does not like is the tail spring. Apparently someone in the past ground down the sides to get it to fit the 1.25 fitting for the Maule assembly. Also, as pointed out by CharlieN, the bend is too sharp.

So now I'm looking for a tail spring that matches the 14-057 in the drawing above. I'd go with trying to rebend, but grinding on the spring means I can't use it.

So it goes. We might make a Champ spring work.

Where did you find a steering arm? I was doing some work on a pre war aeronca L bird and the steering arm looks like that but the holes are worn out pretty good


Sent from my iPhone using Tapatalk
 
Wasn't paying much attention. I ran Maules for 55 years (only on lightweight Cubs) and had made my peace with them. They are not great tailwheels, and the jerking reported in post 1 might be a design characteristic, unrelated to the rudder connection.

The 3200 will of course cure your problem, as you will see. We found it to be the only solution on Stinsons, Maules (!), and Super Cubs. It is the gold standard.

But for the smaller Cubs, we graduated to the API last year. Double-fork, so I can get the Cessna towbar on, and I added an additional fiber (Bakelite) washer at the bottom of the kingpin to give the swivel some friction (a shimmy damper), and now with many hundreds of pavement landings on two Cubs, I am happy to report - bulletproof. But caution - without the damper it will shimmy. All good tailwheels have some form of damping.

Oh - and with 6000 tailwheel hours, count me in the "loose chain" group.
 
Worn holes can be welded shut then re-opened if a compatible filler material is used. Seen it done in the last century.

A 7GCBC tail spring might fit the Commonwealth frame. An 8GCBC is even longer to the wheel if needed.

Gary

Edit: A search for Scott tailwheel rudder arm shows several on E-Bay.
 
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They are so worn there isnt enough room to drill them out. And they are oblong. Thats why you put an AN42 eyebolt in them
Use the worn out edge of the oblong hole as a limit. Clamp it in your drill press or mill. Mill a proper sized hole centered on the original hole for a 1/4" od press fit bushing. If it will take an AN42 it will take a bushing. If it's worn beyond that, just center your new hole and bush it. Slide an over length steel bushing in the new hole. Then with your tubing flaring tool, flair the two ends.
 
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Where did you find a steering arm? I was doing some work on a pre war aeronca L bird and the steering arm looks like that but the holes are worn out pretty good


Sent from my iPhone using Tapatalk

Ebay. But it did not match the part number on the drawing. This arm is fairly unique--I saw lots of Scott steering arms with shorter arms that fit inside the rudder tube. This one fits on the outside.

I emailed the seller for dimensions and decided to buy it to see. It turned out to be the exact thing shown in the drawing.
 
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