There have been many posts about bending brass tubing, and in the past, I have mentioned replacing it with copper tubing (available from most Auto Parts stores for about 50 cents a foot).

Well, a picture is worth a thousand words so here goes...

To prove my point, Last night I wrapped a piece of 1/8" copper tubing around a 5/23" landing gear wire just to show you how well this stuff bends.

I didn't do anything special; no heat, no filling with sand, or weed wacker line. I just held the gear wire in a vice, and wrapped the tubing around it.
(And yes, fuel will still flow through it)

Is there a danger with copper that it is more susceptible to fatigue crystallisation caused by vibration? I thought that this was the reason for using brass in preference...

Any metallurgists out there who can help?

I have been using copper for about 12 years with no ill effects. In fact, at least 2 of my planes that have copper tubing are over 9 years old.

I would think most vibration would be absorbed by the fuel tubing and the rubber tank plug. Not a metallurgist, but I would imagine it's not a problem in the short lengths and silicone cushioned installations we mght use.

Metal to metal connections might be another concern. (Remember when we had to make our own tanks for free-flight and control-line out of sheet brass?)

Thanks for the great idea MinnFlyer.

Charlie P.

The only thing "wrong" with copper as opposed to brass is weight. But in the small amount we use on large planes that isn't a problem. If brass was of the same wall thickness we might feel differently about brass. The only reason to use brass IMO is for bushings or where you need an assembly to maintain it's "roundness" and "staightness". Copper is so much easier to use. Because is has a thicker wall it is much easier to silver solder as it won't burn through as will thin wall brass.

Bish

There y'go see. I learned something today, so I ain't dead yet. Thanks...

As a glider man I really did not know. Now I do

I'm working on a scale exhaust for a 1:6 scale Beaver and need to bend some 1" dia aluminum tubing with a .08" wall thickness. Two 45 degree bends need to be made at either end. I've heard that filling the tube with sand before bending it can help to make a smooth bend. I'm thinking about trying to borrow an electrical conduit bender, which may work.

Ideas??

MinnFlyer - you the man!!

Another nice thing about using the copper...

I make the lines much longer than the tubes that come with the tank. Then I bend them however I need them so I can put them right through the fire wall. That way, there is no silicon tubing behind the fire wall (where a split can ruin your airplane even if it IS fuel proofed).

Minn, were did you get the tubing?

I recently opened a tank that is only a couple years old. The brass inside the tank literally crumbled. I've never had that happen before. I'm wondering if it's the fuel I'm using or if the brass is a different composition than I've used before. I'm thinking it's the fuel, but I'm not using anything much different than I've ever used. Wildcat 15% premium (synthetic/castor). I might just try out the copper tubing.

Bill,
Go for it. Too much time messing with sand.
Tip for Alum tubing, crutches and walkers have some nice anodized diameters and are cheap second hand here!

Any fuel with nitromethane in it will eat holes in brass over time.

You can get the copper tubing from almost any Auto Parts Store. I've never seen one that didn't have it, although some only sell it in pre-packaged bundles of 6 or 8 feet, but many will cut it to whatever length you want. And it only costs about 50 cents a foot. As I said, I've been using it for over 10 years with no ill effects.