High aspect ratio wings

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stanislavz

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Just a Heads-up, there is a Carbon STRIP product, produced somewhere in Europe (1.2mm/ 1.4mm thick with widths 50, 100, 200). It's sold by Sika as a Reinforcement to Concrete Buildings Bridges etc. it's called CarboDur S512. If anyone in Europe is reading this could they tell me where and by who exactly, is making this product - it would be greatly appreciated. It may well be a Sika owned Company. I can't get much sense from the local so called experts in Sika Australia.

In my opinion this is ideal for Spar caps as it can be easily bent and stepped to cater for the elliptical distribution loads. It would be easier to manage and the Carbon Rod Voids (filled with resin) would be avoided.
The strength and resin content is similar to the Carbon Rods and is readily available here in Australia whereas products from Europe and US is much more expensive to procure. I awaiting response from Sika on my questions.

There is another manufacturer in China using German Technology and Equipment, that Company is called 'Horse', the product may be as good, research and time will tell.
George
https://mpkm.org/carbonwrap/

http://carbonwrap.su/

I can read it as being produced in Russia..

But not able to find is it as only produced in Russia, or not.
 

Speedboat100

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You can find a some carbon fiber on fleabay for fraction of shop prices - ie 8oz / 16 oz (300/600) ud for ~ 1.5/3 usd per square metre.

But even if buy new - pultruded carbon is a winner - i would not bet my life under locally sourced wood spar.

Is the wood in your country rotten ?
 

sming

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it's called CarboDur S512. If anyone in Europe is reading this could they tell me where and by who exactly, is making this product - it would be greatly appreciated. It may well be a Sika owned Company
I don't know if it's them, but member Autoreply mentionned multiple times the dpp pultrusion company, as a leader in this domain: https://www.dpp-pultrusion.com/en/the-product-micro-pultrusion-products/standard-pultrusion-sections-in-carbon-epoxy/rectangular-rods/
prices: https://shop1.r-g.de/en/art/610305
It looks cheaper than the Sika product?
 

danmoser

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From reading it sounds like the higher aspect ratio you can make your wing the better. Less induced drag and high lift/weight. Why then would we continue to use low aspect ratio designs? Are they less efficient at speed?

Feels like I'm missing some piece of information.
Others have given you some good answers already, but I'd like to add a couple other high aspect ratio wing characteristics;

* The lift from a high AR wing is more sensitive to angle of attack changes.. This means a higher AR aircraft will generally give you a rougher ride in turbulence when there are vertical gusts.. this also means that you have to be more careful on landing approaches to stay in the correct glide path at the correct airspeed. Google "lift curve slope vs aspect ratio" for more information.

* Higher AR wings are generally less stable around the yaw axis.. meaning that you generally should design the high AR aircraft to have more vertical stabilizer area to provide adequate stability and damping. I qualify with "generally" because there are other geometric factors, such as wing sweep and twist, that are also significant.

* Higher AR wings generally exhibit more adverse yaw tendency.. IOW, tending to yaw out of a turn when you roll into it... you can compensate by using extra rudder input at the beginning of the turn, and/or employing differential aileron motion in your aircraft design.

+ Higher AR wings have a greater tendency to over-bank in a turn.. this is due to the greater difference in airspeed between the inside and outside wing tips, compared with a shorter span craft turning at the same average airspeed.. extra caution must be exercised to avoid wing tips stalls.

* Induced drag is dominant at the lower end of the airspeed range, and less significant at the upper end. So if your main objective is maximizing cruise speed, parasitic drag reduction via streamlining and reduction of wing area is more important than increasing wing span.
 

Lendo

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Stanislavz,
The Carbon Rods are well proven, especially in the States, there is many and varied ways their used. My preferred method is in a Carbon Spar, with Carbon Caps, extremely light and extremely strong. There is round and rectangle rods available through Jim Marske and he produces a Manual to show how to calculate what's needed.

The issue for us in Australia is the initial price, exchange rate, and transport costs - so we search for something supplied (at least) Locally.

The beauty of the strips is that their thin easily kept in shape and bent into the Dihedral angle - price is yet to be established.

I had been contemplating winding my own Caps with Carbon TOW, Yes! it has been done before (in Glass), but the PULTRUDED strips, would make it so much easier and lighter.
George
 

Lendo

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Sming,
I know about DPP but thought they did rods like the US product, however with your prompt I will investigate and THANKS!
George
 

lr27

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Nov 3, 2007
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Nope. But have to source it. Dry it, And hope to be ok :) My grandfather was an Woodworker. So i do know how to work with wood, that to expect from it.
ANC-18, as I recall, has criteria for grading wood. If you are strict about it and maybe test a few random samples, I think you can do a little better than "hope to be ok".

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Lendo:
The allowables I've seen for carbon tow are much lower than for pultrusion, but maybe you can work up a process that's more consistent and perhaps keeps tension on the fibers during the cure? It would probably involve a fair amount of research, work, and testing before you could really rely on higher allowables. How much money it would save you, and how much work would be required to save it are of course significant questions.

I've seen pre-cured carbon strips and sheets which have been tested to at least 150 kpsi by someone I know. The material usually comes in multiples of .007" thick. My guess is it's uni cloth cured under controlled conditions. Those results are from some years back, and probably didn't have enough samples for complete confidence, so it would be prudent to verify. If you were laying up more than one layer of uni, you'd probably do best to avoid the kind with cross stitching or anything else that prevented the fibers from being really straight. It makes a difference.
 
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