Layup issues

[Gilo]

Hello everyone

I posted earlier about an intended build with the following dims

2mm - 11mm - 2mm

The ski is 1800 long and 140-100-120

15.5oz biax
3.5oz UD CF (full width)
Core (11mm)
3.5oz UD CF (full width)
15.5oz biax
fabric
Topsheet

I have now done this and the build went well, but came out too soft - next time I would go for 2.5 12 2.5. As a result I had to re-press the ski with another strip of 100mm wide 3.5oz UD CF. The second pressing and the addition of a veneer top sheet have resulted in a very nice flex and stiffness. So much so I built a second pair for my son. However and as you will have spotted the layup is asymmetrical and there may be issues ahead.

I am in the process of making a third pair of skis for my daughter and would like to avoid an asymmetric layup. Her skis will be the same core material but the dims are:

2-10-2

Ski 1700 130-88-119

My materials are limited to the biax glass and uni Cf that I have. Any suggested layups?

I was thinking perhaps extra gf on both sides or perhaps a smaller (50mm) carbon strip on both sides

Any suggestions gratefully received

I'll post pictures later on when all the skis are done (I am also make a full on, full rocker powder ski).

Thanks

Gilo

[MontuckyMadman]

Tough to say not knowing the weight of the intended rider or ski ability or age. A 10mm core will be rather soft at 170cm or rather a 150cm core??

[Gilo]

Sorry it has taken me so long to reply.

Daughter is 18 and a good skier. The ski is intended to be a ladies AM ski - a do it all daily driver.

She is about 5'3" and about 98lbs. Strong as a whip.

I have been pondering extra GF or extra carbon - can't decide which

Thanks

Gilo

[RYM Experimentals]

What's GF stand for?

[twizzstyle]

(probably typo? GF = FG)

[Akiwi]

In Germany it is Glassfaser = Fiberglass.

[chrislandy]

(probably typo? GF = FG)

Nope, in the UK we say both Glass Fibre (GF) and Fibre Glass (FG)

[Gilo]

Very definitely glass fibre!

The infinite flexibility of the english language

[RYM Experimentals]

Just noticed that your limited to biax glass? It will be hard to get a stiff ride out of biax. Id recommend ordering up some triax and give that a shot.

[Akiwi]

Or add a layer of UD (Uni Dimensional)
or Un dead
or Utterly Dumb

Sorry, I see there is UD in there

[chrislandy]

Also, as you are of the southern flatland persuasion, if you ever get up to Bristol then pop in and see Wiz at Matrix ( http://www.matrix-composites.co.uk/ ) explain what you want and see what he's got on the shelf, last time I was there he had 100mm wide rolls of triax carbon

[Gilo]

Chris - thanks for the tip re matrix and the triax carbon

Ryme - I can get triax glass but I was experimenting with the biax in order to reduce weight by using the uni carbon to act as the longitudinal stiffner. The cores are ash and polar and shouldn't have too much torsional flex - that's the theory anyway.

Giles

[Bloefeld]

The stiffness of a beam is the cube of the distance between the midline of the two skins. If you want to increase the stiffness without changing your layup I would add about a mm to the thickness of the core. You can add thickness with more composite but you will gain little in terms of performance and add a lot more weight.

Try triaxial braid. I get mine at A & P Technologies.

[mikic1]

Hi Gilo,

I made a simple simulator here to be able to verify and experiment with flex,
http://www.junksupply.com/ski-calculator/

hope it helps a bit.