Clamp on vs weld on float fittings

[Charlie Longley]

I’ve decided to set my Super Cub project up for floats. What’s the consensus on clamp on vs weld on float fittings? Anything else that should be done during rebuild?

 

[skywagon8a]

The clamp on is particular to the make and model of floats you will use and are part of the float installation kit.
The weld on you will have to develop your own fitting to join to the rear strut.

Installing the bolt on fittings is not a big deal when the time comes.

 

[Charlie Longley]

The camp on is particular to the make and model of floats you will use and are part of the float installation kit.
The weld on you will have to develop your own fitting to join to the rear strut.

Installing the bolt on fittings is not a big deal when the time comes.

Doesn’t Atlee have weld on fittings? Anything else to consider during rebuild?

 

[skywagon8a]

The drawings for the weld on fittings are on the Northland Super Cub drawings available here: https://store.straight-level.com

Just a few pieces of flat 4130.

 

[skywagon8a]

Structurally there is a small difference between the two. Not a particular advantage for one over the other.

The weld on fittings hold the strut fitting away from the fuselage so that the loads must be transferred through the fitting, the attachment bolt in double sheer then into the longeron tubing at the welds.

The bolt on is just a saddle on which the lower longerons rest. The bolts which hold the fitting to the fuselage are just there to keep the fitting aligned and from falling off.

 

[Farmer Hank]

This is a homemade float fitting on my EAB SC.

 

[Steve Pierce]

Less corrosion issues with clamp on fittings since they can be removed and tubing treated. Found corrosion in the cracks and crevices of weld on fittings. Also find Airframes fittings fit the bend at that station better than Atlee's without having to fill in as much gap.

 

[Charlie Longley]

Less corrosion issues with clamp on fittings since they can be removed and tubing treated. Found corrosion in the cracks and crevices of weld on fittings. Also find Airframes fittings fit the bend at that station better than Atlee's without having to fill in as much gap.

Yeah that’s what Skysigns told me. So bottom line is I don’t really need to do anything special during the rebuild for a possible future float install? (I actually don’t have a float rating.)

 

[skywagon8a]

If EDO still made 2000s, it is an 8 hour job from the time you open the crate until the Cub goes out the door on floats. That's assuming a stock Cub which no one has altered in an inconvenient location.
If I were you I would look at Aerocet just a half day's drive east of you. Ask them about their rear fittings. Their 2200s would be my choice of what is currently in production for a new straight float.
https://aerocet.com/products/2200#block-397

 

[stewartb]

I can’t imagine preferring bolt-ons. I have no floats in my future but my plane has welded fittings. If I don’t run bolts through them, they’ll still have the original paint when I hand the plane over to the next owner. If the paint gets chipped out? I’ll give them some CorrosionX like the main gear fittings.

 

[Steve Pierce]

Mark Englerth can explain it to you. Made perfect sense to me coming from a guy who spends a lot of time 9n floats and is methodical about maintenance.

 

[stewartb]

Maybe salt water guys have different priorities. I like welded.

 

[Steve Pierce]

I've seen rust in the cracks of Super Cubs that have never been on floats. Talking to Mark about it the biggest thing was being able to remove, inspect and treat. Learned a lot about floats from Mark. He has operated them for a long time and I respect his experience and knowledge.

I maintain a couple of fresh water float planes but they have welded fittings. About all I can do is blow out and spray Corrosion X in there.

 

[stewartb]

To the original question, I just walked the dog around my home strip. There are 11 Cubs parked outside this afternoon. 10 on Bushwheels and 1 on amphibs. 11 of 11 have welded float fittings. Clearly it’s a popular mod whether going on floats or not. Maybe it’s an Alaska thing.

 

[Steve Pierce]

Yep, weld on are way more popular but giving an alternative option and reasons.

 

[cubpilot2]

If EDO still made 2000s, it is an 8 hour job from the time you open the crate until the Cub goes out the door on floats. That's assuming a stock Cub which no one has altered in an inconvenient location.
If I were you I would look at Aerocet just a half day's drive east of you. Ask them about their rear fittings. Their 2200s would be my choice of what is currently in production for a new straight float.
https://aerocet.com/products/2200#block-397

I put Aerocet 2200s on a couple years ago and as I recall the STC calls for welded on fittings.

 

[stewartb]

I wish Aerocet would come out with a 2200 amphib.

 

[Charlie Longley]

To the original question, I just walked the dog around my home strip. There are 11 Cubs parked outside this afternoon. 10 on Bushwheels and 1 on amphibs. 11 of 11 have welded float fittings. Clearly it’s a popular mod whether going on floats or not. Maybe it’s an Alaska thing.

Well this Cub will be based in the Anchorage area when done..

 

[stewartb]

Well, hell. There’s no better place to get a float rating in a Cub than around here. The land of a million lakes. Rivers are fun, too.

 

[aktango58]

If you weld on fittings, be sure your welds do not have any voids. The corrosion issue is that water finds a way into any nook and cranny. Most weld on fittings do not fit perfectly onto the frame, and even with a perfect fit, there is space between the tubes and fittings. That space is the incubator for rust.

The bolt on fittings use a U-bolt to hold the fittings on. Quite often the torque and abuse transfer from floats to the frame through the U-bolt can damage the tubes. I have been told also that the U-bolt can be tightened such that it will crimp the tubes.

Long story short, no perfect answer. Planning to weld fittings on my Maule, though I don't have plans right now for floats.

As far as the corrosion, reality seems that the planes around Anchorage have more trouble with cellulose friction or air molecule velocity than rust, (meaning that trees and windstorms seem to damage more planes than the float fittings rusting).

 

[skywagon8a]

The bolt on fittings use a U-bolt to hold the fittings on. Quite often the torque and abuse transfer from floats to the frame through the U-bolt can damage the tubes. I have been told also that the U-bolt can be tightened such that it will crimp the tubes.

There is supposed to be a flat saddle between the U bolt and the tube to prevent this.

 

[AkPA/18]

My issue with weld on is that I just can't see a way to get a good preventative coating between the fitting and the tubes. I haven't tried as my flying cub came with them, so someone smarter than me can probably figure someway to accomplish that. Weld on fittings are needed product for our old cubs as bolt on are hard to acquire. And yes salt can be a problem. A friend of mine got a cub fuselage in to rebuild and as he put it, the longerons were barely holding hands under the Weld on. This is the only fuselage like this that I am aware of. I have a new replacement powder coated fuselage ordered without float fittings but I also have a brand new never used set of boltons that came with my floats. Just personal preference on going that direction. Weld on fittings are great just be vigilant in that area. Rust never sleeps.
Thank for bringing me out of hiding Steve!

 

[1934A]

Here's a trick that would work to prevent rust... Before welding the fittings on, coat the fitting and longeron with soldering paste, then weld the fitting on. After it's welded on, heat it up enough to pull solder into the void between the longeron and float fitting. Done correctly, it would completely fill the void.

 

[The Kid]

I have had bolt-on float fittings, on my Piper airframe, for my 2000s. Now I have an Airframes fuselage with welded. 1. Would Aerocets bolt right on and 2.I didn't understand what I have to do to put my 2000s on that is different from when I put them on the original airframe? Speak slowly as I am slow.

 

[skywagon8a]

I have had bolt-on float fittings, on my Piper airframe, for my 2000s. Now I have an Airframes fuselage with welded. 1. Would Aerocets bolt right on and 2.I didn't understand what I have to do to put my 2000s on that is different from when I put them on the original airframe? Speak slowly as I am slow.

With the clamp-on fittings there is one bolt which goes through both the strut and the fitting.
With the weld-on fittings, two bolts are required with an additional fitting between the strut and the weld-on which accepts both bolts at 90 degrees to each other.

 

[55-PA18A]

I have had bolt-on float fittings, on my Piper airframe, for my 2000s. Now I have an Airframes fuselage with welded. 1. Would Aerocets bolt right on and 2.I didn't understand what I have to do to put my 2000s on that is different from when I put them on the original airframe? Speak slowly as I am slow.

I'm only familiar with EDO 2000's and how they attach, but I originally had bolt on fittings and replaced with AD weld-on aft fittings during recover. These weld-on fittings come with a "swivel block" (see the photos on the AD web site) which bolts between the fitting and the float strut. There is no difference on how you attach the float struts. You'll probably be able to use the same bolt/clevis pin you used with the bolt on fittings.

Charley, many have gone to the weld-on fittings, so if you want to use the bolt-on fittings it probably wouldn't be too hard to find a used set. If you want to buy a new set, be sitting down when you're told the price. As noted in previous posts those fittings have "U-bolts". However, they really aren't regular U-bolts, but special bolts sold by EDO with rolled threads. So if you find a used set, be sure it has the correct bolts and saddles. Again, if you have to buy new bolts, the prices will stun you.

In the original post you ask what else you might need to do during your build. For the 2000's, cables run from the water rudders to the rudder horn on the bottom of the plane's rudder. A pulley is attached to each lower longeron for the cable running from the rudder horn, forward to the pulley, down to a pulley on the float, then back to the water rudder. Typically this pulley is attached to the lower longhorn by cutting a slit in your fabric and inseting a stainless strap (or adell clamp) around the longeron and fasten with eye-bolts for attaching the pulley bracket. So, while you're building, you could weld on tabs with nut plates like you would use for belly panels and thread in the eyebolts for the pulleys.

Jim

 

[skywagon8a]

Typically this pulley is attached to the lower longhorn by cutting a slit in your fabric and inserting a stainless strap (or adell clamp) around the longeron and fasten with eye-bolts for attaching the pulley bracket. So, while you're building, you could weld on tabs with nut plates like you would use for belly panels and thread in the eyebolts for the pulleys.

Jim

If you use the EDO eye bolts for this you will need a stack of washers also as the eye bolt will be too long to tighten to the bottom.

 

[BC12D-4-85]

I've had a couple of float installs with these clamped to the longerons. Two side by side with a hole in each thumb pad spaced accordingly for a bolt to hold the rudder pulley brackets. Maybe a bush fix but worked.

Gary