Aluminum vs Brass bushings

[Paul Taylor]

I'm going to bush my wheels. Will aluminum tubing bushings work as well as brass?

[Wynn Robins]

why are you bushing wheels???  dont they have a nylon hub?

[Bill Gruby]

 If you are talking about K&S Tubing listen to Ty. K&S Aluminum is 6064 T6 and extremely soft.

 "Billy G"

[Jim Kraft]

Wynn; They do have nylon hubs, but in the larger sizes they are usually drilled out to 5/32", and need to be bushed for 1/8" axles.

[W.D. Roland]

The K&S tubing seems to gall worse than any aluminum I have ever tried.

The T6 would be about a medium hardness I think.
6064 is alloyed with lead.
The alloy would explain the galling.
Hard to believe that it is T6 heat treat

Don't know much about all the various Aluminum alloys other than 6061 T6 has properties similar to mild steel.
The other is that trying the K&S for axle bushes didn't work very well.
K&S brass works good.


David

[John Stiles]

I generally scavenge plastic tubing in the correct size to bush axles with. It's not a huge task when you realize that spray bottles like windex and other spray cleaners all have straws that extend to the bottom of the bottle. I've used wd40 straws and q-tips for hinge pins and stuff like that. Much lighter than brass.

[George]

Wynn; They do have nylon hubs, but in the larger sizes they are usually drilled out to 5/32", and need to be bushed for 1/8" axles.

How about affixing the tubing to the axle and letting the friction be between the nylon wheels and the tubing?

I have not tried this, just asking.

George

[Ted Fancher]

How about affixing the tubing to the axle and letting the friction be between the nylon wheels and the tubing?

I have not tried this, just asking.

George

Just a FWIW comment regarding wheels and competition stunters.  Whatever the mating surface between the wheel and the axle I always put some sort of "braking" material between the wheel and the wheel collar which allow me to restrict the freedom of the wheel to rotate.  The "brake disc" can be something as ordinary as a 1/8" id "O-ring".  I personally made up a little cutting jig that allows me to cut of ~ 1/16" donuts of fuel tubing.  When the wheel is installed I apply pressure to the collar while tightening the set screw, being careful to achieve equal tension on both main gear wheels.  When my wheels are set to my preference they cannot be spun on the axle but still roll when the weight of the airplane is on them.

 The primary reason for doing so is to increase the pilot's control over the touchdown and roll out, especially in windy conditions.  An airplane that will roll forever with zero friction on the axles can get you in trouble when rolling around the circle into a strong wind.  In addition, if you've had a bit of bother starting the engine the extra five to ten seconds of rollout could easily put you over the eight minute limit thus forfeiting your landing points (and now, again, pattern points).  One other advantage that is harder to quantify is that on touchdown (on smooth hard surfaces) the small amount of drag on the wheels will have a small tendency to draw the main gear aft a fraction.  This is generally a positive asset as it moves the touchdown point of the wheels back towards the CG a small amount reducing the tendency for the tail to drop and set the wing at a positive angle of attack and perhaps balloon the ship back into the air.

If you fly off grass all the time its not an issue.

Ted

[John Stiles]

How about affixing the tubing to the axle and letting the friction be between the nylon wheels and the tubing?

I have not tried this, just asking.

George

Good answer!

[W.D. Roland]

Hi Ted
I have tried the brake idea before and it works well and also helps to lenghten take off run on airplanes that like to leap into the air.
My problem is 3-4 flights and the friction material is gone. Mostly exhaust residue and grit do the outside wheel brake in first.
Have wanted to try phenolic washers but so far have not.

What are your thought on the Phenolic?

Thanks
David

[john e. holliday]

Go carbon for brake pads/discs.   

[PJ Rowland]

It looks more professional when your ship rolls to a nice controlled stop, instead of going around and around. My first time flying over concrete, had a hot landing downwind and proceeded to roll 1 1/4 laps........ It doesnt look very appealing.

Watched Ted at the 2004 Worlds, His landing was crisp and to the point - the Number 9 point at that.

[Pat Johnston]

I have had to bush the wheels, too.  Here is a trick that is really cool.  There are really neet little 1/8" long brass gromets which fit the 1/8" grear nicely and are a handy, easy way to bush the wheels.  Brodak sells them, along with other hobby suppliers.  I keep a stash of them in my parts tackle box for this purpose.  Simple and easy.  The nicely rolled flange on them is a clean facing on the outside, too.
Pat Johnston
Skunk Works

[rustler]

Remember the (probably apochryphal) story concerning Steinway pianos. This salesman was trying to sell them his new ali pivot pins. Steinway knew their brass ones were the best, but this salesman was persistent. Eventually Steinway said to the guy "Tell you what sir, we'll build one piano and test your pins. Then we'll decide". Salesman overjoyed. "Great, when shall I come back?" - "In about 100 years".

[Ted Fancher]

Hi Ted
I have tried the brake idea before and it works well and also helps to lenghten take off run on airplanes that like to leap into the air.
My problem is 3-4 flights and the friction material is gone. Mostly exhaust residue and grit do the outside wheel brake in first.
Have wanted to try phenolic washers but so far have not.

What are your thought on the Phenolic?

Thanks
David

David,

I've not had that problem although I must point out that any airplanes I fly a lot are tuned pipe powered so the oil isn't an issue.  I'm not an expert on phenolic material.  I always thought it to be a hard substance and I wan't something that I can compress with finger pressure so as to be able to adjust the drag on both wheels the same (or a smidgin more on the outboard side for takeoffs).

Ted