Tempered Aluminum?

epanzella

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I've been flying RC planes for a good many years now and have a lot landing gears laying around. New ones are getting pricey so I'd like to recycle some of the old ones. They look to be made out of 1/8 inch aluminum that has been bent to shape. . They've all been drilled for previous planes so to recycle them I would need to TIG the holes shut and drill new ones in the proper locations. The problem is that these landing gears are springy so they can take quite a bit of deflection and return to their original shape. What makes them springy rather than ductile? Is it the alloy or some kind of heat treating and will the heat of TIG welding change the properties of the material? If they become soft and bendable after welding then they will be useless. Any incite will be appreciated.
LANDING GEAR BLOCK 2.JPG
 

kb58

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Welding it will absolutely reduce its stiffness to that of 1000-series aluminum - dead soft. It is possible to temper it, but it's not nearly as simple as annealing. What you have there will bend like it's made of lead.

Also, aluminum work-hardens. This means that with use, it'll get harder and harder, and eventually crack. Not a great choice for landing gear, but if you keep an eye on it, it can be replaced before cracking through.

My advice is to replace it with an thinner (and more aerodynamic) strip of steel. To achieve the equivalent stiffness, a strip of aluminum and steel will end up having the same weight.
 

Latinrascalrg1

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I agree about the aluminum not being the best choice! If your looking for a low cost replacement look for some of that metal banding straps used to tie down pallet loads and such. That stuff if usually a spring steel and can be trimmed down for weight purpose and will last much longer then the aluminum and best of all can be had for free, usually just have to ask!
 

royesses

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I remember when a teen building u-control and RC airplanes in the 50's and 60's those landing gear were made of Dural® aluminum. It is considered non weldable. Very springy and tough for aluminum but great for landing gear.
Here is some info from mat web:

Material Notes: High strength, low weight alloy; in the solution heat-treated and aged condition, mechanical properties are as good as, or better than, low-carbon steel. Limited weldability. Used in aircraft and aerospace applications. Poor corrosion resistance.
Made from aluminum, magnesium and copper. More info available on the internet. Search for Dural®


Roy
 

RobertB

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I remember when a teen building u-control and RC airplanes in the 50's and 60's those landing gear were made of Dural® aluminum.
They still are. Most of the RC catalogs usually list them as "Dural Landing Gear"
 

Chewy

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Doing the Google thing. This stuff has a dozen trade names under Duralumin. Used by Zepplin in their airships. Here is link to a post from 2013 Home Machinist: http://www.chaski.org/homemachinist/viewtopic.php?t=97444. Look up the 2024 material and it shows friction welding only and is readily available. The 2000 series of aluminum is interesting. I am only familiar with 6061 & 7075 & cast aluminum.

I learn something new everyweek from this group. Thanks Charles
 

epanzella

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Well if I can't move the holes in the gear I'll have to adjust the threaded holes in the fuselage to match the existing gear. Thx for the replies.
Ed P
 

markba633csi

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I agree with RobertB: just slot the holes and put washers under the bolt heads- unless that won't hold firmly enough and works loose? If that's the case then yes, make new ones out of steel instead
M
ps alternately, perhaps you could try filling the holes with epoxy mixed with aluminum filings
 
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rzw0wr

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Depending on how far you need to move the holes.

You can drill them out big enough to include the new hole.
Put a small screw in the threads of the plug and work the plug down.
On a thin piece of stock like yours a little AC glue may help.

All you need is a plug large enough will let you get 1/2 or better of the new hole.

The plug needs to be of the same material of the that is being plugged unless the plug is big enough to iclose the entire new hole.
A soft screw works great.

We did this at work about every day.

Dale
 

MrWhoopee

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The aluminum alloys most frequently used in manufacturing are 2xxx, 6xxx and 7xxx series. 6061 is the one most commonly available. They are all precipitation (age) hardening alloys.


When these alloys are welded, the heat affected zone becomes solution treated (frequently, if incorrectly, called annealed), making it soft. It can be re-hardened, but because the entire part has not been equally heated and the filler material is not the same as the base material, the hardness will vary. In welded parts, the machinability of the heat affected zone is poor because the material is soft and gummy. Machinability can be greatly improved by boiling the part in water for a couple of hours or longer.

Welding up the holes in your landing gear will soften the area immediately around the hole making it easy to bend. You MAY be able to recover some of the hardness by boiling or heating in an oven at temps up to 350 F., but this will also affect the material not in the HAZ. At some point, over aging begins and the material starts to get softer. I would suggest a non-welding method of plugging the holes, but the strength will never be equal to the material that has not been drilled. Also, if 2024, welding is not recommended, it has a habit of cracking.
 
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AGCB97

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I had an ultralight airplane and it used 7075 for the gear
 

JPMacG

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Some of my RC planes had the aluminum gear still labeled "6061T6" when I opened the box. I think they were in kits from Great Planes.

I have reused landing gear many times. I just drill more holes. Some of mine look like Swiss cheese. If one hole breaks into another it is no big deal - a washer covers it.

I have never had aluminum landing gear fatigue and break. I have had them splay from hard landings many times. I just bend them back using a vise. On the other hand, carbon fiber landing gear love to crack.
 

WarrenP

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I have never had landing gear break on a RC Plane but they seem to break rather easily on RC helicopters for some reason. Must be how they land.
 
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