Help! Making landing gear

[FlyawayClyde]

That is a neat bit of handy.....

 

[acerc]

If you stick to about 1.5 x the diameter in radius you should be ok. At 5/8” that is 2x. You may wish to consider some mild steel cold roll rod versus the piano wire or drill rod. Less tendency to crack in those tight bends, but you’ll have less “spring” available to you before it takes a permanent set. Probably doesn’t matter much in that application. Where is the tight radius located and how many degrees are you talking?

Here is a pic of the same style gear, the arrow denotes the bend I am talking about, that is the only bend that will be that tight. I believe the rest would be ok. I know I said 5/8" but the wire may be a tad smaller, won't know for sure until I get closer to needing it.

 

[acerc]

Ok hear goes trying my best to explain this tool and how it works. Bolt is 1/2 socket head screw and the pins are 5/16 drill rod. ( you can use a drill bit or any steel). The bolt is the item that the wire is bent around that is why I used a 1/2 inch bolt because that is the correct radios up to 5/16. Bent 5/16 but never anything heavier. Top plate is just leverage to bend the wire make it as long as you which, it is made from 1 inch wide by 1/4 by the length you need. The smaller block of steel is the block that is held by the vice. When it is in the vice the pin in that block is what stops the P.W from rotating. So you put the wire between the pin and the bolt. The pin in handle is what is used to wrap the wire around bolt. So with bottom part held in the vice with the bolt through both blocks of steel when you rotate the it pivots around the bolt wrapping wire around bolt.

This is a very doable tool, thanks.

 

[Alky6]

Here is a pic of the same style gear, the arrow denotes the bend I am talking about, that is the only bend that will be that tight. I believe the rest would be ok. I know I said 5/8" but the wire may be a tad smaller, won't know for sure until I get closer to needing it.

If that gets brazed to the axle support that goes vertical including the washer, I wouldn’t worry about it cracking a little bit. And further with the struts included, you should be fine with mild steel cold rolled, IMHO.

 

[acerc]

If that gets brazed to the axle support that goes vertical including the washer, I wouldn’t worry about it cracking a little bit. And further with the struts included, you should be fine with mild steel cold rolled, IMHO.

What do you consider mild steel?
By the way this will be a 40lbs'ish airframe.

 

[Alky6]

What is cold steel?

When steel is rolled through dies, it is done either hot or cold. Hot is cheap and usually has a dark crusty finish and os inconsistent in its sizing.. Cold rolled is the same process but the steel is formed cold. Takes a heck of a lot more pressure and work to form the steel into the determined shape. Cold rolled has a nice finish on the exterior of the surface and is typically much more workable and machinable and has consistent sizing along its length. ASTM A 108 -1018 is a very common mild steel (low carbon). It is also available in small sizes 1/4”, 5/16, etc.
An example of a supplier:
https://www.fastenal.com/products/details/47704

 

[Alky6]

What do you consider mild steel?
By the way this will be a 40lbs'ish airframe.

To give you a rough order of magnatude on the capacity of a 5/16” A108-1018 rod in straight compression (one rod by itself), assuming no buckling, you would be good for about 1,000 pounds (Using allowable stress). Your design in the photo has three separate legs - call it good for 1,700 pounds. On a 40 pound plane an assuming a single tire hard hit that is a 43 g load. That would bend the axle long before the strut failed.

You may wish to consider using piano wire for the piece that makes up the axle. The big concern you would have (if you were an aircraft full scale) is repeated loading and fatigue failure. With steel, as long as you remain under 50% of the yield stress, the member would have infinite life. But again, to give you a sense of maganatude - we are talking hundreds of thousands to millions of cycles. With your landing gear, I doubt you would ever see that.

A108 1018 has a yield stress of about 56ksi. Compare that to piano wire or spring steel and the yield stress is over 200ksi. (1 Ksi = 1,000 psi). It is designed to handle more cycles.The yield stress is equal to the point at which you bend the material and it takes a permanent set (it is bent at that point).

 

[Snoopy1]

Here is a pic of the same style gear, the arrow denotes the bend I am talking about, that is the only bend that will be that tight. I believe the rest would be ok. I know I said 5/8" but the wire may be a tad smaller, won't know for sure until I get closer to needing it.

Here is a pic of the same style gear, the arrow denotes the bend I am talking about, that is the only bend that will be that tight. I believe the rest would be ok. I know I said 5/8" but the wire may be a tad smaller, won't know for sure until I get closer to needing it.

Trying to understand the picture of the landing gear. Could you take a picture from the front. Just look at how the gear will carry the load or impact. Looks like three legs going to either wheel. Would like to see how the centre leg is supported and how it is connect to the plane. But just for reference you mentioned that you are trying to wrap or bend the wire around the axel. If I understand you correctly and I understand the gear setup then I would use piano wire but at the location of the axel just heat it up to a very dull red in the dark and wrap it around the axel. At that location the strength of piano wire is not required and the loss of some strength due it a little stress relief will not in way comprise the strength of the gear. But please understand that a can not see exactly how the gear is put together. Just trying to help.

 

[49dimes]

Ok..... just throwing this out here.....found that cool bending tool on ebay for about 70 bucks. What's nice about it is that it does ribbon or flat stock and tubing along with solid wire. https://www.ebay.com/itm/New-Manual...332070&hash=item4d50faeac3:g:ybMAAOSwmiZZwdxi

 

[acerc]

But just for reference you mentioned that you are trying to wrap or bend the wire around the axel. If I understand you correctly and I understand the gear setup then I would use piano wire but at the location of the axel just heat it up to a very dull red in the dark and wrap it around the axel.

This confirms what I was thinking or hoping. Thank you.
I am not quite sure as to the rest of the gears design until I get that portion of the airframe framed. But like posted earlier the rest of the bends will be minor in comparison.