Source for Carbon Rods?

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stanislavz

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Once tested and incorporated into wing load calculations, approximately how much more % weight did your self made uni caps need compared to calcs for similarly functioning pultrusion caps? Did you do any type of comparisons at the calc stage?
Also you can find this on Jim book on composite. On compression it was at least three times worse.
 

davidjgall

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Does anyone have drawings/layup schedule lists for extremely lightweight wings using CF pultrusions and probably CF Dtube in the design? for wings in the 70-130 sq ft area range and design gross weights under 400lbs is what I am interested in seeing. Glider aspect ratios preferred.....
Marske Monarch 'F' plans. Buy them from Jim Marske.
 

davidjgall

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"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.
When Goodwinds says they are no longer manufacturing "longer lengths," they are speaking in relative terms. I spoke to them last year (they actually invite phone calls on their website -- check it out!) they said that they had a shipping liability issue with the big 1000 ft coils. There is a LOT of potential energy stored in such a coil and they were having issues with people cutting the restraining tapes and having violent unwindings, etc. Their manufacturing process was thus modified: they now "only" make 200 ft segments and then cut those up to ship. I asked whether I could order custom cuts, say, 30 ft and they said yes, but that shipping would be my problem since they were not interested in coiling the product. A length of PVC pipe could be a suitable and reuseable shipping container, I presume, and such lengths could easily be shipped by truck. So, if you "just gotta have" Goodwinds' product it IS possible in the lengths we need for wing spars.

As for vinylester matrix material, there is a strong case in favor of that but it requires SANDING (roughing up) the individual rods before bonding and that is a process that adds time, complexity, and quality control issues that are best avoided. According to Jim Marske in my conversations with him, that is the primary reason he stopped carrying the rectangular rods. The smaller diameters of round rod are (were?) still manufactured with epoxy but that may also be changed since I did my research. I would not hesitate to use vinylester-matrix rods for my own design and build, doing my own testing along the way, of course. Vinylester has been used in many homebuilt planes and kits, such as the Glasair series, and it makes secondary bonds with epoxy just as readily as epoxy-based parts do; in fact, I'm surprised that the epoxy-based rods do not also require sanding prior to bonding since epoxy does not make chemical bonds with cured epoxy so the resulting mechanical bond is identical to a bond between epoxy and vinylester.

Disclaimer: I'm outside my field of expertise on these issues so everything above is subject to being completely wrong -- DYOR. The Marske design method that acknowledges the extreme flexibility of long, lightweight structures resulting from use of these rods (glider wings) and, thus, designs to deflection criteria and results in huge strength margins, that method MUST be tempered by designers of stubby-winged things that approach anything close to (more than 1/2) the material strength limits and appropriate testing becomes obligatory. However, the material is so light that doubling or quadrupling the margins by "pretending" that the material is only 1/2 or 1/4 as strong as the test coupons predict can still result in significant savings over other materials, whether in weight or cost or uniformity or availability. Caveat Emptor.
 

proppastie

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The Marske design method that acknowledges the extreme flexibility of long, lightweight structures resulting from use of these rods (glider wings) and, thus, designs to deflection criteria and results in huge strength margins,
how does one determine "deflection criteria"?
 

stanislavz

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Marske Monarch 'F' plans. Buy them from Jim Marske.
Or jsut his old web site. Can't find it now. But its shows you layouts + ribs spacing. Plus some tests on single skin made from cf / vs fiberglass.

And yes - he was not using foam in his wing from start.. Only on later design.
 

patrickrio

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I have the Marske "Composite Design Manual" ordered already, hasn't arrived.

I just went to his website and I could find no pricing or way to order monarch F plans. It really isn't what I am interested in for me personally but I would like to see some general wing construction details if I could. I could not find layouts/rib spacing on the website.

I am mostly interested in more modern/recent designs that have higher L/D with lower wing area for similar or lighter gross weight than the Monarch design.
 
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stanislavz

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I am mostly interested in more modern/recent designs that have higher L/D with lower wing area for similar or lighter gross weight than the Monarch design.
Monarch is a kind of floater - D cell + fabric. Similar is all carbon, carbon dragon - D cell with single cf + cf ribs. No foam.. All standart gliders are much faster and have less wing - so no fabric, only rigid skin.
 

Lendo

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patrickrio, 400 lbs. is very light is that the MTOW, or just the weight of the aircraft?
Generally speaking it's the MTOW plus HT download less the wing weight multiplied by the G rating you wish to apply.
That is the maximum load carried by the wing at the fuselage attachment points, half of which is carried by each wing.

Using Jim Marske's Manual you calculate the Max rods at attachment points. The minimum one would have at the tips of wings is 2 Rods.
The rods are very strong and Wing Tip Flex should be considered/ calculated following Marske's method.
What's not in the manual is he uses the 'rule of thumb' of reducing the rods evenly along the length of the Wing. This gives an even flex.

That's the best I can do for you.
George
 

proppastie

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Are Jim's gliders ultralight USA part 103. I think 150 lb empty?
 

TLAR

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Patrickrio, there is a wealth of information on HBA. Anyone interested has gotta get out the shovel und use the search function.
This will brush up your reading comprehension skills. No offense intended. In the end every calculation is just a guess. Testing is required, but just tlar will get you into the testing phase.
Lendo I appreciate you posting I learn from you.
DavidJGall I would be inclined to sand epoxy rods. Secondary bonding with confidence requires attention to detail. Ain’t no doubt about it
 
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patrickrio

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Yes I know 400 is light. I was just using weight of the whole aircraft at max takeoff weight.

I picked 400 as that is the max weight of the Wood Skypup. In the vicinity is fine too, for sure below 450lbs gross is what I am wanting to see. Aircraft that accomplish this will probably have different construction techniques than 1000+lb max gross weight gliders.
 

patrickrio

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Patrickrio, there is a wealth of information on HBA. Anyone interested has gotta get out the shovel und use the search function.
This will brush up your reading comprehension skills. No offense intended. In the end every calculation is just a guess. Testing is required, but just tlar will get you into the testing phase.
Lendo I appreciate you posting I learn from you.
DavidJGall I would be inclined to sand epoxy rods. Secondary bonding with confidence requires attention to detail. Ain’t no doubt about it
Yes, I have been digging. Finally figured a way to search only "The Light Stuff Area" with google so now search is working better..... couldn't figure out how to use this websites advanced search to only search that sub topic forum so my searches were not targeted before.

spoke too soon. search technique failed....
 
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stanislavz

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TLAR

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Patrickrio
The SkyPup is ripe for an upgrade, I am 50ish% through it with about 85% to go.
Waiting on engine development from Russia.
The pup has one sweet ass wing. I’m gonna put Ailerons on my version
 

patrickrio

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Patrickrio
The SkyPup is ripe for an upgrade, I am 50ish% through it with about 85% to go.
Waiting on engine development from Russia.
The pup has one sweet ass wing. I’m gonna put Ailerons on my version
Sometimes I am not sure if you are serious or if you picked TLAR because you wanted to humor troll people.... hahah.

Assuming you are serious, how are you going to change that wing to get ailerons on it? by the time you strengthen the back edge sufficiently to add ailerons, and add torsional strength so it won't twist as you flip them from side to side, I think the wing would be a ground up redesign......
 
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