Production carbon mast composition

[cwood]

Are all production carbon masts foam centered?

I broke my Moses Vorace mast yesterday and got to see the construction...clearly two halves bonded with a thin white foam core. I believe the engineering of carbon is all about the skin and not a core...but wondered if some are solid layers of carbon? I would think layup would be difficult to do solid and heavy....would it be stronger?

[Mossy 757]

Are all production carbon masts foam centered?

I broke my Moses Vorace mast yesterday and got to see the construction...clearly two halves bonded with a thin white foam core. I believe the engineering of carbon is all about the skin and not a core...but wondered if some are solid layers of carbon? I would think layup would be difficult to do solid and heavy....would it be stronger?

Most race foils are solid carbon now, especially those with longer struts that need the extra stiffness compared to a 70cm strut which can be built with less materials but similar stiffness (stiffness decreases exponentially as length increases).

[KristianE86]

stiffness decreases exponentially as length increases

I am sure the relation is polynomial (cubic to be specific): https://en.wikipedia.org/wiki/Euler%E2% ... eam_theory

[jaros]

I broke my Moses Vorace mast yesterday and got to see the construction...clearly two halves bonded with a thin white foam core. I believe the engineering of carbon is all about the skin and not a core...but wondered if some are solid layers of carbon? I would think layup would be difficult to do solid and heavy....would it be stronger?

It would be nice to see a photo of the broken section. We rarely have a chance to see the inside construction of our toys.

[cwood]

I broke my Moses Vorace mast yesterday and got to see the construction...clearly two halves bonded with a thin white foam core. I believe the engineering of carbon is all about the skin and not a core...but wondered if some are solid layers of carbon? I would think layup would be difficult to do solid and heavy....would it be stronger?

It would be nice to see a photo of the broken section. We rarely have a chance to see the inside construction of our toys.

Here you go. Foam looks to be about 1/4 inch at its thickest. Two bonded halves. I think the bond may have failed, then separated, then due to there not being opposing forces of two sides it broke. I had felt some strange behavior on the wing just before....thought I had picked up a weed or something. It actually failed when starting after being in the water. I think I was lucky not to have lose the wings and fuselage. 1km body drag back to shore.

https://goo.gl/photos/SbCbKBydD4rmb5mv8

[Lokihel]

Solid carbon does not make sense, and would be painfully hard to manufacture.

Foam core will give a bit of compression to the layup and keep it light.
Ideally you'd want a hollow shell with a bladder during the autoclave cook, although I don't know how many manufacturer do this, as getting the bladder out is complicated enough a yacht mast.

You could also do two halves, which is probably the easiest way of getting good compression on your laminate, but you then have a weak point at the joint (as seen on the pictures). I have also heard of Gunboat rudders splitting in half at the joint for similar reasons.

[james]

Solid carbon (monolithic construction) is far easier and more common in the high end marine industry than you think

With a precision mould and pre preg fibre you can know precisely how many layers and where they need to be place for a desired thickness

Pop it all in an autoclave and it cooks and moulds it precisely

[renaudbarbier]

all our mantafoils (and earlier zeeko) carbon masts are monolithic for the last 10 years and honestly you save surely some weight and carbon cost with foam inside but on the other hand it is not as strong or thin as it could be with full carbon. having said that the last mm in the center are useless and usually filled with the glue.

as mentioned the prepreg process makes this it even easier

[BWD]

Sorry about the broken mast! Ouch, but glad no injury or loss of parts.

Have had this idea for a while, seems a good place to put it:
Why not lay up a mast with a couple layers of nylon webbing at the center to avoid risk of foil loss in failure, save a few layers of cloth/grams of resin, etc.?

[NorCalNomad]

Sorry about the broken mast! Ouch, but glad no injury or loss of parts.

Have had this idea for a while, seems a good place to put it:
Why not lay up a mast with a couple layers of nylon webbing at the center to avoid risk of foil loss in failure, save a few layers of cloth/grams of resin, etc.?

You wouldn't need a couple layers. 15MM tubular Nylon webbing has a 10.2Kn breaking strength (2,300lbf.) and 8MM tubular Dyneema webbings are up at 22Kn of breaking strength.

Interesting idea, but how often are fuselages breaking off masts (or masts off mounts)?