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tcraft128
08-11-2009, 08:23 PM
There has been a ton of discussions on what spring can be used, but what the different spring specs are and what are the differences in height, stiffness and overall effectiveness have yet to be determined. Lets assume it is for a 1 hole tail wheel.

So, what spring are you using? (Std or extended gear?) What springs have you BROKE? What springs are the tallest? Shortest?

Any others you have found that are worth adding?

-Jay

Here are some links to univair's offerings.

3 leaf pawnee
http://univairparts.com/shopping/product_info.php?products_id=10056

4 leaf pawnee

http://univairparts.com/shopping/product_info.php?products_id=10055

Pa-18 4 leaf
http://univairparts.com/shopping/product_info.php?products_id=10049

mike mcs repair
08-11-2009, 10:15 PM
usually I put only 3 leafs on all my projects......

remember as you (need to)put more leafs on and use it hard/turn in tundra you will be doing more welding repairs to back end...

bent/flat spring and rudder much much cheaper....

aktango58
08-11-2009, 10:55 PM
No vote for stock spring.

jgerard
08-12-2009, 12:04 AM
After fixing a few twisted tails on aircraft equipped with the 1 3/4" Pawnee springs I think I like the idea of a more forgiving stock 1 1/4" 4 leaf setup. Having a spring that can twist side to side might be a good thing.

I have yet to see a set of new tail wheel leaf springs that don't need additional arc put in them before use and again after a few hundred hours of use

Arcing springs is easier than fixing bent tubing or broken longerons.

Jason

Flying Miss Daisy
08-12-2009, 06:40 AM
Jason,
I have the Pawnee setup and never had issue with it and never had a tailwheel shimmy until I put on the 31s and the baby bush. Now if I land on pavement any bit hot at all I am getting a major shimmy. It has been my understanding that a shimmy is from the angle of the spring causing the tailwheel angle to be aft in a flat configuration which puts it off center.
By the way this is not with a heavy rear load?
John

supercrow
08-12-2009, 06:56 AM
Hi John: The angle of the tailwheel is most often the problem with the shimmy. However, in your case you already have the ext. gear and now the taller tires, and more tailwheel tire surface on the pavement, which does in fact mean considerably more tail weight on the ground in a three point position. The higher the nose gets, the heavier the tail gets when the machine is on the ground. Hope to see you at Greenville on your flyout day. Reid

Steve Pierce
08-12-2009, 07:33 AM
AK Bushwheels Husky tailspring is the best way to go in my opinion. See the other thread for details.

willyb
08-12-2009, 08:29 AM
I had tailwheel shimmy for the first time a couple weeks ago when landing on pavement(I love grass).Checked everything and all is tight.Looks like the spring has settled since new and it needs to be re-arched to get some more caster in the pivot.I may try a wedge between the spring and tailwheel first before I bend the spring.

Bill

tcraft128
08-12-2009, 08:36 AM
Here is a link to the Husky spring from ABW.

http://www.akbushwheel.com/HuskyTailspring.html

Steve, do you run one of these? What is the differance when mounting? How does it sit compared to the PA-18 spring?


-Jay

jgerard
08-12-2009, 09:43 AM
John is right, the width of the spring will not keep the tail wheel from shimmying. It's the arc of the spring and the castor angle that affects steer-ability and shimmying.

I think I remember that the factory had a hard rubber shim between the tail post and the springs. I see a lot of planes with out any shim at all. I replaced the rubber shim with a 3/16" aluminum one on my plane.

I baby my tail. I never taxi with the stick all the way back in my lap. I keep as much weight off the tail as possible and push the stick forward when making turns.

Try sitting in the plane with the brakes on and at about 1/2 throttle. Move the stick back and forth and take notice of how much the tail spring is flexing from the down force applied by the elevator.

I like to think of tail wheel springs and hardware as wear items. Every time I change the oil the tail goes up on a stand to level the airplane. This way I can easily inspect the tail wheel setup with no weight on it.


Jason

jgerard
08-12-2009, 10:04 AM
This happened when the tail was swung around to park and the tail wheel hit a small hole. The plane has the "X" brace installed and every thing aft of it bent.

Jason



http://www.supercub.org/photopost/data//500/medium/DSCN1878.jpg
http://www.supercub.org/photopost/data//500/medium/DSCN1881.jpg

OLDCROWE
08-12-2009, 11:13 AM
AK Bushwheels Husky tailspring is the best way to go in my opinion. See the other thread for details.

Ok Steve, Now I'm really confused...

Kirby

SteveE
08-12-2009, 12:25 PM
Jason,,, Might be a good reason for the Baby Bushwheel..... It might have just bounced out of the hole.....

Course I havent seen the hole either.

OldCuby
08-12-2009, 01:17 PM
Like Jason, I baby my tailspring. Now only wheel landings on hard surface and low downward forces. This keeps me awake on landings! I've 2 sets of stock springs(Univair) and keep one set rearched ready to go when the other set has lost its arch. I've rearched each set once. I wonder how much they can take? I guess eventually they loose their spring and need to be trashed...
Taking up some of my 200+ lb passengers really gives 'em a workout!
Jim

OLDCROWE
08-12-2009, 01:30 PM
There has been a ton of discussions on what spring can be used, but what the different spring specs are and what are the differences in height, stiffness and overall effectiveness have yet to be determined. Lets assume it is for a 1 hole tail wheel.

So, what spring are you using? (Std or extended gear?) What springs have you BROKE? What springs are the tallest? Shortest?

Any others you have found that are worth adding?

-Jay

Here are some links to univair's offerings.

3 leaf pawnee
http://univairparts.com/shopping/product_info.php?products_id=10056

4 leaf pawnee

http://univairparts.com/shopping/product_info.php?products_id=10055

Pa-18 4 leaf
http://univairparts.com/shopping/product_info.php?products_id=10049

From my order placed Monday with Univair that may not be the correct part number for the 4 leaf PA-18, they said that one is for the solid tail wheel? I'm not sure but they seemed quite sure and what they are sending me was a bit more buck$.

Kirby

hotrod180
08-12-2009, 02:12 PM
AK Bushwheels Husky tailspring is the best way to go in my opinion. See the other thread for details. Ok Steve, Now I'm really confused...
Kirby

I'm looking for a replacement tailspring assembly for my C150/150 taildragger. The existing tailspring set (3 leaf) doesn't have enough arch, and is too soft to boot. The ABW site doesn't show any dimensional data for the Husky tailspring. I emailed them about a week ago asking for info on length and curvature angle, but no reply. This tailspring assembly BTW is 1-1/2" wide and about 18-1/2" between the forward (fuselage) and aft (tailwheel) mounting holes. The Sprice catalog shows dimensions for several possible replacements, unfortunately they're all too short by several inches. A shorter spring assembly won't work as the fuselage mounting hole can't be moved aft, and if the t/w was moved forward the steering chain angles would be totally out of whack. I'd appreciate any ideas on a suitable replacement.

Eric

jgerard
08-12-2009, 03:59 PM
Eric,

I'd re-arc them with a bench vise and a 4' chunk of pipe.

Jason

hottshot
08-12-2009, 05:52 PM
This happened when the tail was swung around to park and the tail wheel hit a small hole. The plane has the "X" brace installed and every thing aft of it bent.

Jason



http://www.supercub.org/photopost/data//500/medium/DSCN1878.jpg
http://www.supercub.org/photopost/data//500/medium/DSCN1881.jpg


Jason I would recomend moveing the attach eyebolts to the bottom of the rudder horn (put spring under rudder horn insted of on top)

DW
08-12-2009, 06:32 PM
Wup have you got those Husky tailwheel springs done yet---I'm waiting--??

Dennis

hottshot
08-12-2009, 06:37 PM
Wup have you got those Husky tailwheel springs done yet---I'm waiting--??

Dennis


Not quite yet ..... still working on one other project that needs done :crazyeyes: :crazyeyes:

hotrod180
08-13-2009, 01:56 PM
Thanks for the suggestion, Jason- I'd try the re-arch but the tailspring set is too light for my tastes anyway, esp since I took some of the weight off the nose. The tail weighs 110 pounds in level attitude. I'd rather just replace the spring assembly with something a bit stouter.
Wup, while you're here..... what's the width & center-to-center dimensions for the Husky tailspring? And maybe the approx angle in degrees of arch? Thanks,

Eric

don d
04-28-2010, 10:40 PM
Any one have a cub type 1 1/4" tail wheel spring that would work on an experimental. I need one but don't want to spend $105....

Don

FdxLou
04-28-2010, 11:16 PM
I have the ABW Husky Tailspring on my Smith Cub and am very happy with it. It replaced a sagging 3 leaf Pawnee spring. I have a heavy Cub with a very heavy tail weight ( too much to comfortably lift).

Like Wup said, it should be approved for certified Super Cub's soon...a great upgrade. And, it is lighter than the one it replaced on my plane!

Lou

Bugs66
04-29-2010, 12:41 AM
I got my 3 leaf Pawnee tail spring from Larry Bauer, www.calumetcub.com . Not sure if he is still selling them but was a good deal.

highroads
06-22-2010, 10:32 PM
I have a PA12, the parts list shows a 3 leaf spring for the tail wheel, the airplane has a 3 leaf spring, single hole type of the correct width. The PA18 parts list I have looked at shows a four leaf spring. The univair catalog shows a 4 leaf spring, same part numbers as the 12, but four vs. three. There are two different mounting brackets called out for the 12 and 18, I assume the difference is the channel depth for four leafs, vs. three. Now the question, is it within conformity requirements to put the four leaf 18 spring and bracket set on a 12? and just for curiosity, since the 12 with a wide fuselage and "2" pass in the back seat, should have the stiffer set up of the 18 tail spring?

Thanks for your comments

Darrel Starr
06-22-2010, 11:30 PM
One thing surprised me about the tailwheel in my SC. When the weight and balance was checked with the airplane empty and up level, the weight on the tailwheel was about 60 to 65 lb. What I didn't realize then was that in the three point attitude with 8.50X6 tires, 3 inch extended gear and with all 44 gal in the Dakota Cub tanks, the weight on the tailweel is around 200+ lb. For planes with Bushwheels, even more weight is on the tailweel as the deck angle increases. Something to think about --- that itty bitty wheel and mechanism is working pretty hard.
Darrel

kevin
06-23-2010, 12:28 AM
I have a PA-12. The shop manual calls out for a 4 leaf, 1 1/4" wide spring. This is the same spring and tailwheel that came on J-3's. If you use the 1 1/4" wide spring, you have to use the converter bracket that goes between the spring and the tailwheel. I did not want to use this converter bracket. I chose to go to the Pawnee spring. It is 1 3/4" wide and fits perfectly inside the tailwheel mount. I only used 3 springs, not 4. It has been said that the 4th spring is too stiff and could make the lower longerons too stressed when encountering bumps. I believe that the 3 spring set up will be plenty strong when loaded. Keep in mind that if you use the 1 3/4" wide springs, you have to use a different bracket that holds the spring up against the spring pad on the tailpost. Univair carries them.

ag-pilot
06-23-2010, 01:10 AM
I have broke several stock and a couple pawnee 3 leaf springs over the years and never bent a longeron. As long as your careful turning a good cub fuselage that has the A model beefups and the longerons boxed will take a hell of a pounding without damage. Side loads from turning is where they get bent. I have run the 3 leaf pawnee setup for a long time and the weak link there is the single bolt that attaches the tailwheel to the spring. ABW's 2 bolt setup looks like a great upgrade to me.

Bent rudders and lookiig for lost tailwheels in the sagebrush isnt much fun

Dave

highroads
06-23-2010, 01:25 PM
Thanks to those that commented, As always this forum and the folks contributing make it more than enjoyable to be part of.