tailwheel spring rear support

[herman pahls 9]

My model 2 Kitfox tailwheel leaf spring is bolted in the front and semi captured in the rear by a C channel and not captured by vertical bolts and a strap on the bottom like I have seen on Model 4 Kitfox's and our Pacer.

Since I started flying on rocks I have removed the steering springs and modified the tailwheel to freely swivel so the tailwheel would not give feedback to the rudder.

My worst fear was a tailwheel leaf spring failure that would put pressure on the rudder that could not be overcome inflight.

My worst fear was realized yesterday when the leaf spring popped out of the channel and it was a none event because I was pushing it into the hanger when it happened.

Even with the steering springs removed, this could have caused a ground loop if I was moving at speed with the tailwheel on the ground.

I mention this since I assume my Kitfox was not the only Kitfox or Avid that came this way.

I plan to weld on some tabs to use bolts to capture the spring.

Anybody done this to share how they solved this issue?

I am concerned about welding right next to the fabric.

Thanks Herman

[Av8r3400 1178]

The rear of the spring should be captured side to side by two bolts and a plate on the bottom, just as you have seen elsewhere.

 

The two bolts should have sleeves on them so that the plate does not squeeze the spring preventing the sliding action between the leaves as it moves through it's range of travel.

 

Does that make sense?

 

 

 

Without a lockup on the wheel, it's only a matter of time before you loop the plane--  Not "if" but "when".  The poor brakes, lack of rudder authority at slow speed along with the short coupled nature of the gear on an early Kitfox will eventually get you.  For your case, I hope the damage is zero to very minimal.

Edited 15 Sep 2013 by Av8r3400

[C5Engineer 1170]

Herman when I upgraded my Tailwheel spring the kit has your drill a second hole farther towards the back of the plane in that plate. You have to grind the head the of the bolt down to the shape of a triangle to fit between where the longerons come together. I just cut a small square out of the fabric back there. The new hole was pre drilled in the new spring. I bolted the original bolt in and then used the new hole as a guide. Was relatively easy. Brent included the ground off bolt in the kit but with a little trial fitting it shouldn't be tough to do. Sorry I don't have any pictures of the new bolt but here's a thread I dug up from when I did the swap. Hope this helps.

 

http://www.avidfoxflyers.com/index.php?/topic/575-double-tw-spring-updgrade/?hl=double

[herman pahls 9]

Thanks Joey and Av8r3400 for replying and the advice.

I have a 2 leaf tailwheel spring similar to Joey's but I do not have the extra hole a few inches back, so Joey's method will not work unless I order a spring like his.

My plan is to flatten the C channel bends to make a flat plate that I can drill a hole on each side of the leaf spring for a AN-3 bolt to capture the spring with a plate on the bottom.

Av8r3400 mentioned that I  should use a steel sleeve on each side of the leaf spring to prevent squeezing the leafs and causing them to bind. 

I found a drawing on line showing the Kitfox Super Sport tailwheel spring installation, using steel sleeves.

What is interesting is that our much heavier Pacer had one -4 bolt on each side  capturing the spring without sleeves.

I tried bending the .070 cold without success and then used acetylene torch which worked well and thankfully did burn  the nearby fabric.

I realize ground looping is an ever present risk especially since my tailwheel is not connected to the rudder and if the brakes were to fail.

When I land, especially on short rough strips the tailwheel does not touch till I have virtually no forward speed.

I appreciate the concern.

Herman

Edited 16 Sep 2013 by herman pahls

[lv2plyguitar 172]

My leaf spring is a double.  One fits nicely in the channel, the other is slightly in the channel.  I overcame your fear by placing Raychem heat shrink tubing over both springs behind the channel closer to the wheel and heat shrinking them together.  That stuff is tough and will not rip.  This keeps the second spring from moving side to side. 

[allonsye 85]

Great thread. Heres my problem on my C HH:

 

I have the original single leaf and it's toast.

 

Calls and email to Airdale are going unanswered.

 

I need to upgrade my leaf spring. Can anyone direct me to a source? I'm not interested in a spendy solution but a simple upgrade to the leaf spring assy (hopefully making it safer and less loop prone) and retain my solid wheel Maule.

 

Thanks,

Paul

Edited 25 Sep 2013 by allonsye

[IFMT 36]

Go to your local machine shop that can sell you a spring a little wider that what is on there now. Match the length and angle. Drill the hole to match the original so your original lays over the new one. Grind the edge of the slightly wider spring to fit the tailwheel mount. You will need a press to get the bend right. Cost me about 30 bucks and it is superior to the original setup. You do need the extra bolt in back to keep it all aligned. I'll take a pic tonight on my way home. Cheers. B

[allonsye 85]

Go to your local machine shop that can sell you a spring a little wider that what is on there now. Match the length and angle. Drill the hole to match the original so your original lays over the new one. Grind the edge of the slightly wider spring to fit the tailwheel mount. You will need a press to get the bend right. Cost me about 30 bucks and it is superior to the original setup. You do need the extra bolt in back to keep it all aligned. I'll take a pic tonight on my way home. Cheers. B

Thanks B  - kinda what I had in mind. Pics would be great so to convey the idea to a machinist. The thing is, how do you know if you have the right spring tension?  I must say though, I live in NASCAR country here in NC --- rife w/machine shops. I should be able to get this done and done well.

 

Oh.....nother thing. As was pointed out above, this does have to be constructed so that the mated leafs are able to slide/move independent of each other right. You mention "extra bolt in back to keep it aligned" -- wouldn't that keep the leafs from sliding independent of each other?

 

Paul

Edited 25 Sep 2013 by allonsye

[akflyer 1427]

Mine has 2 bolts in it also.  The 2 spring can still slide at the bend point.  A custom 4X4 shop should be able to do the work also.  My first set of springs were not even tempered.  I think someone just went down to the local metal supply shop and grabbed some flat bar and bent them.  The least little thump on the tail wheel would flatten the damn thing right out.. I ordered a set of springs from Airdale (in 08 or 09) and have only bent those when I hit a frozen snomachine track.. but that thump woulda bent ANYTHING I had back there!  Make sure if you have it re-arched, that your geometry is good and the king pin is vertical or steering will suck at best..

 

[allonsye 85]

Mine has 2 bolts in it also.  The 2 spring can still slide at the bend point.  A custom 4X4 shop should be able to do the work also.  My first set of springs were not even tempered.  I think someone just went down to the local metal supply shop and grabbed some flat bar and bent them.  The least little thump on the tail wheel would flatten the damn thing right out.. I ordered a set of springs from Airdale (in 08 or 09) and have only bent those when I hit a frozen snomachine track.. but that thump woulda bent ANYTHING I had back there!  Make sure if you have it re-arched, that your geometry is good and the king pin is vertical or steering will suck at best..

 

There's something to be said about a sacrificial annode of sorts - it's easier to replace a bent TW spring then a bent section of fuselage in my humble opinion.

 

"keep the King Pin vertical". Oh yeah! In it's present state it won't swivel at all.

[Av8r3400 1178]

I need to upgrade my leaf spring. Can anyone direct me to a source? I'm not interested in a spendy solution but a simple upgrade to the leaf spring assy (hopefully making it safer and less loop prone) and retain my solid wheel Maule.

 

 

 

Link

 

Call these guys.  I know they do this, cheap...  (hint hint.)

[allonsye 85]

Link

 

Call these guys.  I know they do this, cheap...  (hint hint.)

Have you used them? They won't say NO because it's for an acft will they?

 

Should I simply have the OEM Avid spring rearched and tempered or go to a dual leaf?

[akflyer 1427]

I would go dual leaf.  Too many single springs have broke and that gets spendy for repairs when the dual springs would have saved it from happening.

 

Every Avid I know of is nose heavy anyways, so throwing a few more pounds on the tail really helps!

 

[allonsye 85]

I would go dual leaf.  Too many single springs have broke and that gets spendy for repairs when the dual springs would have saved it from happening.

 

Every Avid I know of is nose heavy anyways, so throwing a few more pounds on the tail really helps!

 

Someone here at work just suggested I simply go to the scrap yard and find springs there and cut them to fit. That actually sounds like a good pennytech idea.

[Av8r3400 1178]

I would not go dual.  Three leafs is the only way.  SIngles break, duals go flat.

 

This shop will talk to you about the spring you need officially for your "go cart".  If you explain that you need one of the 1-1/2" wide springs they have made for the airplane guy in Rhinelander, he will understand.

 

I think you will have $50 with shipping...

[allonsye 85]

I would not go dual.  Three leafs is the only way.  SIngles break, duals go flat.

 

This shop will talk to you about the spring you need officially for your "go cart".  If you explain that you need one of the 1-1/2" wide springs they have made for the airplane guy in Rhinelander, he will understand.

 

I think you will have $50 with shipping...

Thanks, I'll call them tomorrow.

[allonsye 85]

Every Avid I know of is nose heavy anyways, so throwing a few more pounds on the tail really helps!

 

Reason enough to go w/a 3/leaf. Mine is nose heavy and requires quite a bit of up elevator trim.

[allonsye 85]

Just found this at Aircraft Spuce. Which set would work?

http://www.aircraftspruce.com/catalog/lgpages/leafsprings.php

 

 

 

 

Edited 26 Sep 2013 by allonsye

[Av8r3400 1178]

$$$$$$ Wow. $$$$$$

[dholly 718]

I would not go dual.  Three leafs is the only way.  SIngles break, duals go flat.

 

This shop will talk to you about the spring you need officially for your "go cart".  If you explain that you need one of the 1-1/2" wide springs they have made for the airplane guy in Rhinelander, he will understand.

 

I think you will have $50 with shipping...

Perfectly sized, arched and tempered 3-spring delivered to your door... for $50!

Oye ve, perhaps it's true... you can lead a horse to water but you can't make it drink?

Personally, I just LOVE it when somebody does all the hard lifting for me. ;-)

[IFMT 36]

Here is what I did. The change up I bought from airdale broke. The top spring is the original avid with the end cut off. The lower is a modified trailer spring.file://localhost/Users/admin/Pictures/iPhoto%20Library/Originals/2013/21-Sep-13/IMG_1138.JPGfile://localhost/Users/admin/Pictures/iPhoto%20Library/Originals/2013/21-Sep-13/IMG_1136.JPG

Sorry guys. Need to learn how to post a picture.

Edited 27 Sep 2013 by IFMT

[akflyer 1427]

When you look at the bottom the reply box, there is a button to hit on the lower right side that says "More Reply Options"  When you click on that on the bottom left side of the box you should see a big paper clip that says attach files and a button under it that says "Choose files"  Click that then browse on the computer to where you have the file on your computer and click the picture.  This will upload from your computer directly to this site and you wont have to link through a 3rd party server like photo bucket or one of those sites.

 

[IFMT 36]

Here is my second picture upload attempt. One thing about the beefier spring is your aoa on the ground will be reduced slightly. If you are running bigger tires on the front it doesn't matter. Also, I have a sube hanging on the front, with extra weight at the back so a beefier spring is needed to take that extra weight. I think a heavier spring that is actually a spring is the way to go. The one I bought from Brett could be easily bent and the tailwheel broke off right at the mount kicking the **** out of my rudder as the springs to the horns dragged it along.

[C5Engineer 1170]

Your TW assembly is bolted to the lower of the two springs correct? Are you able to break your TW free with that set up? I had to extend my arms and then I tossed the Maule assembly and went with a Matco and then upgraded to the Matco dual fork 8" and haven't looked back.

[IFMT 36]

Yes the tailwheel would break free as it is intended. I took the cam of so it wouldn't break free after reading some other posts. I sure like the handling a lot more without it breaking free unexpectedly. The assembly is bolted to the lower spring. And yes I'm looking to upgrade too!