Carbon fiber lay up

[revhed]

Yes, there is a system proposed by Frankite ( for sure one of the true fathers of modern foil design and build) on the french forum.

http://kitefoil.forumactif.org/t1580-me ... ion-du-mat

I just read it again and will get some more specifics before posting here.
In a nutshell, as you mentioned, it is about fixing the base plate vertically and adding weight to the strut and measuring deflection.
And adding weight to the fuse and measuring twist.
I am off to sleep so will try to get to this tommorow.
It would be cool if guys out there with other foils (home made and commerical) could add their findings as well!

[Soren Gabriel]

I have been following this post about layup of front wings with interest as we are a bunch of friends working on a DIY kite foil project. Until now we have only been posting about in Danish
(https://www.facebook.com/#!/groups/dani ... lbuilders/ ) but I am planning to make an English summary for Kiteforum as soon as we have tried the foils (hopefully during Easter).
We have already made our first front wings by making two halves and gluing them together. From the molds we have made we end up with a stiff but very thick (15 mm) 600 mm straight wing. The production is quite time consuming and we would like to make something a bit thinner and more race like. Therefore we are discussing to layer up a fiberglass blank and shape some different wings from that.
I wonder if anybody has experience with this method and if you have suggestions for the necessary thickness of the wing. We are working with two layers of biaxial glass 430 gr (15 oz) and then a lot of unidirectional 600 gr (21 oz).

[TPink]

Yes, there is a system proposed by Frankite ( for sure one of the true fathers of modern foil design and build) on the french forum.

http://kitefoil.forumactif.org/t1580-me ... ion-du-mat

I just read it again and will get some more specifics before posting here.
In a nutshell, as you mentioned, it is about fixing the base plate vertically and adding weight to the strut and measuring deflection.
And adding weight to the fuse and measuring twist.
I am off to sleep so will try to get to this tommorow.
It would be cool if guys out there with other foils (home made and commerical) could add their findings as well!

Hey Rev,
any luck getting some english specs on stiffness testing?
I'm holding on my vid till I can do the lab work.

Thanks,

[revhed]

Hello tpink,
What I do not know fron frankys info is where to measure the flex of the strut?
I see what I think is a trace at 85 cm but that would mean the weight is at about 75cm.
Look carefully at the photo.
this needs to be standard to be acurate!
If you place, hang, 5 kilos, 5 liters of h2o at 85 cm from the t bar top do you measure at the 85 cm?
The twist is easy to see.
But it seems that you could hang at 30 from the axis of the strut and not have to add a bar forward?
I was waiting to contact him to ask, so now I will.
R H

[TPink]

Thanks!

That's why i asked. i did look at the photo's and tried to understand some of the french speak, but couldn't determine where they actually took the measurment from. There would be a relatively large difference between measuring the flex at the end of the strut or at the 85cm point.

Also if they are including the base when measuring out to the 85cm point or starting where the strut intersects the base. I guess i could do both...

on the torsional twisting test, it seems that the weight and position of that clamp holding the measurment arm would play a roll in the test results? no? Also the point where the vertical post holding the strut level meets the fuselage. In the pic it looks slightly aft of the center of the strut.

[revhed]

Ok I got some info.
He repleyed and said this.
He felt he was not as accurate as possible, and after a short communica decided this.
Mount the base plate SOLIDLY at vertical, 90°, strut parallel to floor.
Measure out along the strut 85 cm, including mounting plate.
Take a measure to the floor, note.
Add 5 kilos, 5 liters h2o,as close to your 85 cm mark as possible, centered on mark.
Take measure to that 85 cm mark, note difference.
For twist, torsion, mark axis, center at fuse connection, of strut, measure back towards tail 30 cm, mark, measure to floor, note.
Add same weight again centered on mark, measure, note difference.
I am now just thinking how to do this with tuttle box systems? Maybe strap board to wall?
I hope to do this with my 3 home made foils and post results but Have MANY other things to do.
Does anyone have a better idea
R H

[Europ2]

When info lies within hand

viewtopic.php?f=196&t=2382637

[tkettlepoint]

thanks Europ2 I was trying to find your post for here...

terrie

[revhed]

Thanx europ2!
Better!
R H

[TPink]

Thanks RH,

I get the measurement set up now.

couple things, on the strut flex, it would be difficult to get an accurate measurment to the floor at the 85cm mark if the weight was hanging at the same spot. You would either have to bend the tape measure around the weight, which would cause inaccuracy, or measure as close to the weight either side and use a right angle devise to measure back to the 85cm mark. Is that your thought on it as well?
On the torsional twist, of less concern, but the clamp holding the bar has a certain weight. That would conteract/counterbalance the twisting moment of the strut. To be truly accurate the weight of the clamp should be known and factored, or more simply, instead of a clamp, a couple wraps of duct tape could be used with the same holding effect, yet far less mass to effect the measurment.

I'll strap mine up this evening and see how she does...