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I made my own tiedown rings.

T

TimSPEED

Active Member
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Hi everyone.
Thought I would share a little side quest I did whilst I am building my RV-8A. When building the wings (I am nearly finished here) I really did not like the way the mount for the tie down rings sat around a quarter inch above the wing lower skin. It means you cannot screw in a tie down ring and do it up tight.
Now I know some would say they don't need to be tight, but really who wants to rely on a bolted type fastener that is not properly tight? And further, the mount is actually stronger when it is tightened up as it reduces bending stresses on the threaded portion of the mount. Not being able to find a satisfactory off the shelf solution, I made my own, and it looks like this.
TW-TD-2.jpg

TW-TD-3.jpg

What you can see is I gave it a small shoulder that reaches thru the lower skin and screws hard up against the internal mount. The hole for the rope to pass thru is 3/4 inch. I think it looks a lot neater.
And, because I wanted it light, I made it from Titanium. As you can see, the part weighs only 36 grams, almost nothing :)

TW-TD-4.jpg

A much cleaner looking solution I would think. For me, I will probably screw them in and leave them in. But obviously, I can still take them out if I preferred that.
 
Very nice!

I recommend that you round the inside of the loop to prevent stress concentrations on your ropes. Otherwise, you'll need to use carabiners, and there goes your weight savings.

Dave
 
i felt the same and just made shouldered sleeves that allow the ring to tighten against the internal block. I will admit that yours is a more attractive and elegant solution.
 
Nicely made, but Is titanium the best material for the job? Thinking tensile strength, brittleness, malleability, etc..
 
David Paule said:
Very nice!

I recommend that you round the inside of the loop to prevent stress concentrations on your ropes. Otherwise, you'll need to use carabiners, and there goes your weight savings.

Dave Looks like he has the inside edges knocked off. its great do way it is
Click to expand...
 
Hi everyone, thanks for the comments, appreciate it! Just regarding strength, I did choose a higher strength grade of titanium, enough that it is stronger than the 316 Stainless I was going to use. So both stronger and lighter. Plus titanium seems cool :). And yes, I did note there are some other similar tie downs to the ones I made, but I did not find any that actually extended thru the lower skin to the mount surface to give a proper solid mount.

Just regarding the interest in obtaining your own set of these, whilst I had not particularly planned on making them for sale, I did make a couple of extra pairs to help justify the effort of CNC programming, setup, and material purchase. Each part I built, at cost for this small batch worked out to $70 USD each ($140/pair) so if anyone would like to help me by sharing in the build I would be happy to sell the spares.

Please send me a message if you are interested. And thanks again for the feedback. I can't wait to use these properly on my own RV.
 
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They are beautiful.
Just another option.
By the way, if you have a space between the tie down bracket and skin, screw in a headless hex bolt with a dab of blue loctite. It will act as a stop so the ring doesn't deform the skin.

I mounted my tie down brackets flush to the skin.
 
wirejock said:
I mounted my tie down brackets flush to the skin.
Click to expand...
Can’t say for other models, but for the 6, per plans, they are mounted flush with the bottom of the spar. I’m a “follow the plans” kind of guy figuring there might be a good reason they did that.
 
a small package reached my house 2 days ago... put those lovely tie-downs to test today, the numbers speak for themselves.
Another weight saving on my neverending quest for efficiency ;)

Thanks for a 1st class product Tim!

IMG_7249.jpegIMG_7250.jpeg
 
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Thanks everyone for feedback on my parts. I have now sold out the remaining of my first small batch, so not taking orders just now.
But thanks so much to the fine folks who did order, much appreciated.
 
I approached the gap between the wing skin and the tie down thread bar from another angle.

I made a packer approx 1 1/2" 3/4" by 1/8" that packed the 1/8" gap between the skin and tie down bar, riveted it to the wing skin so now am able to screw the tie down hard up against the skin.

Just my solution

Rob
 
Dan 57 said:
@F18Sailor
bought the stuff a while ago, but nails were from Aliexpress of 12" length.
Here's one of the article, Aircraft Tiedown, on the subject by Vintage Airplanes:
Click to expand...
Hey Dan,

I recognized the design...they call for 18in stakes. I settled on some 40cm (~15.75") Ti Stakes from Aliexpress: Boundless Voyage Ti Stakes

I do wonder what the pull strength is for shorter; that would ease the baggage requirements a little bit!

-Sam
 
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