Source for Carbon Rods?

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Lendo

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BoKo, those thin wide strips from China are for external concrete strengthening, like for older concrete Bridges and the like. Their strong in tension as their very high tensile strength, to my mind that makes them less suitable for Aircraft Spars, which is best suited for moderate Tensile strength, which is far less brittle.
Jut my opinion after researching the material and considering the flexible strength needed for Spars.
I am interested in your tests, perhaps their strong enough, but you will have very stiff wings and don't mind a rougher than normal ride.
George
 

berridos

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Do you test yourself the compression or send it to a lab? Would be nice to shed some light on the test.
 

Lendo

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brridos, there different strength carbon rod test videos on the internet, if I had one to hand I would attach it, but the bending strength example of High Tensile Carbon Rod compared to a moderate strength, was very obvious.
As Billski always says, always test!
George
 

BoKu

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The critical metrics here are modulus and compressive strength. I will be fixturing coupons to go to a friend's testing machine to get these values. Unfortunately too late to appear in the article on load testing he's publishing in Kitplanes in a month or two, but a sidebar on my tests on RV-8 landing gear hardware will be in there.

Edit add: fixturing coupons of stuff like this for compression is harder than it might seem, and the results are not always clear-cut. A lot of it is about getting the column length right. I intend to make coupons of both the China material and its Goodwinds equivalent so we can make meaningful comparisons.
 
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Lendo

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Good work BoKu, I'm keen to see the results, have you considered Carbon for the Main Landing Gear Legs?
Billski help me with an example using Carbon.
I worry about where materials comes from, from Goodwinds, without a QA Certificate, I'd probably be happier with Rod material from Jim Marske. Anything from China is suspect IMHO. From research I've found material quality from Taiwan seem to be much better and they have International QA standards.
George
 

dino

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Wouldn’t a simple deflection test between the standard and the unproven sample provide at least a qualitative comparison?
 

BoKu

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Wouldn’t a simple deflection test between the standard and the unproven sample provide at least a qualitative comparison?
Sure, that will give us the modulus. But what we really need is the compression strength.
 

tailwind

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Thats the problem with composits coupon testing, it is very subjective to the actual usage and structure. So a coupon test numbers have to be tested with the builders processes. If cure, atmosphere, support structure.
 

Lendo

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David Gall - that's news to me , did you get that from Jim Marske himself. I've had discussions with Goodwinds in the past - it wasn't very encouraging. Perhaps check with the Manufacturer, as far as I was aware Jim was their preferred agent.
George
 

davidjgall

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David Gall - that's news to me , did you get that from Jim Marske himself. I've had discussions with Goodwinds in the past - it wasn't very encouraging. Perhaps check with the Manufacturer, as far as I was aware Jim was their preferred agent.
George
Yes, I got that information from both Jim Marske and from speaking directly with Goodwinds on another matter, a conversation that drifted into talking about Jim whereupon I said that I also wanted some products that Jim carries, to which Goodwinds replied that I should order those materials from him.
 

BoKu

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how are those made ..... glue?....what do you use?
Yeah, I'll glue the strips into the blind holes in the aluminum slugs using the EA9360 left over from the last set of CElipse wingtips. This is the compression coupon arrangement shown in the recent Kitplanes article on materials testing by Eric Stewart.
 

Matt K

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I had been discussing the rod issue with Jim for some time.
This is from email Jim sent about a year ago.

"Our carbon rod source is in jeopardy. My supplier (Goodwings) says the rod is now made with vinylester resin instead of epoxy. Not good!
I placed an order for a supply of rod but Goodwinds say they are no longer supplying long lengths.?? I don't think that's the truth.

I tried to call the manufacturer, Diversified Composites, but got no answer. Their web site says they sold out to a European company. I'm afraid they may have shut them down. The only other suppliers are in China and that's not good either. "

Jim did design a spar using rods made from vinylester resin. The bigger rods only came in vinylester. I built it with epoxy and got good results. I don't know what numbers he used for modulus and strength but know they were different that epoxy rods. I had the calculations some where but cannot find them.

Last time I spoke with Jim he talked like he had a deal to get a batch of old rods but that didn't happen.

I have some original rods if they are needed for comparison testing.

When we first learned of the rods there were being used in wing spars for V-22 Osprey. Not sure if it was a prototype or production version.
 

blane.c

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I had been discussing the rod issue with Jim for some time.
This is from email Jim sent about a year ago.

"Our carbon rod source is in jeopardy. My supplier (Goodwings) says the rod is now made with vinylester resin instead of epoxy. Not good!
I placed an order for a supply of rod but Goodwinds say they are no longer supplying long lengths.?? I don't think that's the truth.

I tried to call the manufacturer, Diversified Composites, but got no answer. Their web site says they sold out to a European company. I'm afraid they may have shut them down. The only other suppliers are in China and that's not good either. "

Jim did design a spar using rods made from vinylester resin. The bigger rods only came in vinylester. I built it with epoxy and got good results. I don't know what numbers he used for modulus and strength but know they were different that epoxy rods. I had the calculations some where but cannot find them.

Last time I spoke with Jim he talked like he had a deal to get a batch of old rods but that didn't happen.

I have some original rods if they are needed for comparison testing.

When we first learned of the rods there were being used in wing spars for V-22 Osprey. Not sure if it was a prototype or production version.
Sad.
 
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