tailwheel swivel release

GeorgeC

GeorgeC

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GeorgeC
When taxiing at low speed, is a (Lang, in this case) tailwheel expected to release into full swivel without the application of brake?
 
In my case, without brakes, it releases to the left easier than it does to the right. I don't know if this is normal or not. Spiraling slipstream? Apparently my tailwheel dresses to the left a bit:tail.jpg
 
Change to a Scott tailwheel.
Your is worn out, you show an old type Maule wheel, those were worn out when I still had hair.
 
It's a Lang, installed new a few years ago.
 
GeorgeC said:
It's a Lang, installed new a few years ago.
Click to expand...
there are several verities of LANG " MAULE " there are all the same.... junk. specialty when they are worn out.
NOTE the wheel in the photo isn't vertical. WHY.. it is worn out.
 
If you ever do go a different model- don’t ignore a rebuilt Scott 2000. I know the 3200 is the Mecca of tailwheel- but it’s more than ya need on the 120/140, nothing wrong w using one either. But the 2000 does great and can’t pop the tube... also lighter
 
Tom-D said:
OBTW,, there is no longer a Scott tailwheel
They are now
https://www.airframesalaska.com/Tailwheel-Parts-s/1814.htm
Click to expand...

Anyone with a Scott 3200 tailwheel should purchase a couple of these in advance...

50025712567_3a1ccbd155_z.jpg


I went through more than a few in my two Citabrias used for tailwheel training. The symptom is the tailwheel will lock in in one direction but not the other.They tend to break at one of the bends.
 
There is a free link to a Maule tailwheel service manual online. Google "Maule tailwheel" and look for Lightlink.com.
 
FastEddieB said:
Anyone with a Scott 3200 tailwheel should purchase a couple of these in advance...


I went through more than a few in my two Citabrias used for tailwheel training. The symptom is the tailwheel will lock in in one direction but not the other.They tend to break at one of the bends.
Click to expand...
The cam plate they lock into also gets worn. The corners of the latching notch get worn off.

The OP's tailwheel is indeed similar to the Maule, and they were never much good. It's kinda sad that you can buy some really nice tailwheels for your homebuilt (like the Matco) that work well and are far less expensive. The Scott is a robust tailwheel but it has its drawbacks, too. It has a brake to try to control shimmy, and that makes it sticky for steering. The McCauley tailwheel was the same but had an external adjustment for the brake. I have found that dynamically balancing the tailwheel itself stops much of the shimmy, and making sure that the steering pivot axis is not tilted forward at the top at all is also very important. Airplanes that mount their tailwheels on flat springs will gradually flatten that spring and mess up the axis. Shimmy follows. If the shimmy is persistent it breaks other stuff, like the Citabria tailpost we had fail due to that.
 
Dan Thomas said:
The cam plate they lock into also gets worn. The corners of the latching notch get worn off.

The OP's tailwheel is indeed similar to the Maule, and they were never much good. It's kinda sad that you can buy some really nice tailwheels for your homebuilt (like the Matco) that work well and are far less expensive. The Scott is a robust tailwheel but it has its drawbacks, too. It has a brake to try to control shimmy, and that makes it sticky for steering. The McCauley tailwheel was the same but had an external adjustment for the brake. I have found that dynamically balancing the tailwheel itself stops much of the shimmy, and making sure that the steering pivot axis is not tilted forward at the top at all is also very important. Airplanes that mount their tailwheels on flat springs will gradually flatten that spring and mess up the axis. Shimmy follows. If the shimmy is persistent it breaks other stuff, like the Citabria tailpost we had fail due to that.
Click to expand...
If you have a shimmy with a Scott it is not rigged correctly.

when the tail wheel is allowed to droop, it will shimmy. at all times the plane rotation of tail wheel must aways be leading edge up.
When the tail spring is allowed have a reverse curve, it causes the spring to be in the wrong position
 
Replacing the tailwheel leaf springs was not an
uncommon occurrence in our Citabrias. Training is tough on them. Twice had the tailwheel pushed up onto the rudder, bending the u-channel on the bottom. I had students and renters take note of the distance between the top of the tailwheel assembly and the bottom of the rudder on preflight. As I recall, it was about the width of an average hand when OK.
 
FastEddieB said:
Replacing the tailwheel leaf springs was not an
uncommon occurrence in our Citabrias. Training is tough on them. Twice had the tailwheel pushed up onto the rudder, bending the u-channel on the bottom. I had students and renters take note of the distance between the top of the tailwheel assembly and the bottom of the rudder on preflight. As I recall, it was about the width of an average hand when OK.
Click to expand...
I was always reminding the instructors and students to report ANY shimmy, especially after it broke the sternpost. That was an expensive repair. Cut the fabric, peel it all back, cut out the lower section of tubing and weld in a new section with an internal tube for reinforcement, and weld on a new tailspring bracket.
When the tailwheel shimmies it yanks the leaf spring back and forth, twisting it at the mount and putting bending loads into the sternpost. That post fatiuges and breaks.
upload_2020-6-20_18-9-48.png
Tom-D said:
If you have a shimmy with a Scott it is not rigged correctly.

when the tail wheel is allowed to droop, it will shimmy. at all times the plane rotation of tail wheel must aways be leading edge up.
When the tail spring is allowed have a reverse curve, it causes the spring to be in the wrong position
Click to expand...
 
Tom-D said:
If you have a shimmy with a Scott it is not rigged correctly.

when the tail wheel is allowed to droop, it will shimmy. at all times the plane rotation of tail wheel must aways be leading edge up.
When the tail spring is allowed have a reverse curve, it causes the spring to be in the wrong position
Click to expand...
That's what I said. If the pivot axis tips forward at the top, it'll shimmy. Same as saying the plane of rotation lower in the front.
 
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