Imperfections Carbon Mast

[BayAreaKite]

@tegirinenashi as many have pointed out in this thread, there is a lot more variability in composites than aluminum alloys. What I gave were generalized numbers for intermediate modulus Toray T700 UD tape. There are also standard, high and ultra high modulus fibers available... and woven, braid, and chopped fiber! I gave compression strength, because composites typically fail in compression, as they are 2-3x stronger in tension. I was quite conservative in these numbers, to prevent someone from calling me out giving values of a high strength fiber. Strength and stiffness are calculated based on tests in which cross sectional area of the sample is required. So no, it's not based on weight (that would be known as specific stiffness/strength) or volume. It is based on cross sectional area. If you look up a "stress vs. strain curve" you can learn a lot about the strength and stiffness of materials, as well as failure modes.

Yes, composites are anisotropic (properties different in each direction) and aluminum is isotropic. However that is the beauty of composites, you can tailor the layup of the mast to give you the characteristics you want/need. Project Cedrus has no 90 degree fibers in the mast. It is a mix of 0 and 45s. Composites that are comprised of a mix of 0, 90, 45 are known as quasi-isotropic. It's the lazy way to design for composites, and the structure is barely lighter than aluminum when done this way. A properly designed carbon structure should be 30-40% lighter than aluminum of equivalent stiffness or strength. Otherwise it shouldn't exist. Project Cedrus is 40% lighter than most aluminum masts. Solid carbon masts are not lighter than most aluminum masts, because they are not optimized and as you point out likely include 90 degree fibers which are contributing nothing to the design.

Again, foil companies are making solid (or wood/foam cored) carbon masts because it is expensive and challenging to make them hollow. But since they are solid, they need to make them thin otherwise they are very heavy and expensive (more material!). When they make them thin, they lose all the stiffness (and strength).

[SMJ]

Project Cedrus is the only hollow carbon mast on the market.

I respect and appreciate your enthusiasm, as I am also an Engineer, but you'd sell more product with full transparency and / or better market research:

https://www.aliexpress.com/item/32873647072.html

https://www.f-one.world/product/carbon-masts-3/

https://www.alibaba.com/product-detail/ ... bb26kuHjxk

Lift also makes a hollow carbon mast.

[BayAreaKite]

Thanks @SMJ, I don't think there's a more transparent foil maker out there than myself. Please buy the "100% Carbon Hydrofoil Hollow Solid Core Mast Carbon Mast" from AliExpress and report here how it goes. Also please share info on the Lift hollow mast, would be very interested in the details. Been selling a lot of masts to Lift riders looking for something stiffer for the new High Aspect wings.

[SMJ]

Deceptive advertising is a crime; you're putting your retailers at risk, so please be careful. A fully transparent OEM would rectify this situation. It wouldn't take much effort to wordsmith the current ads into something factual.

https://www.ftc.gov/tips-advice/busines ... rules-road

https://www.mackiteboarding.com/project ... rbon-mast/

[windmaker]

Project Cedrus is the only hollow carbon mast on the market.

I respect and appreciate your enthusiasm, as I am also an Engineer, but you'd sell more product with full transparency and / or better market research:

https://www.aliexpress.com/item/32873647072.html

https://www.f-one.world/product/carbon-masts-3/

https://www.alibaba.com/product-detail/ ... bb26kuHjxk

Lift also makes a hollow carbon mast.

Duotone also make a hollow mast so that's at least 4 brands.

[BayAreaKite]

Would love to see pictures of all these hollow masts you speak of, especially Lift. As far as I know they are foam cored. My definition of hollow or thin-walled structure is more cross sectional area devoted to air than material. Those Chinese masts are hardly hollow. They have a void in the middle, but they're still thick laminates that weight more than the aluminum masts. Here's a sample section of Project Cedrus (minus leading edge):

Project Cedrus Section

[sonny2727]

despite all the claims of masts from big brands failing, I haven't seen this in recent years and given the number of masts in circulation from companies like Moses its obvious that there is no problem here to solve by a 747 engineer ...and copying a good design is never been easy so big brands can/should/have copy best design and making mast is not rocket science ...common we are not talking about SpaceX here?

[windmaker]

despite all the claims of masts from big brands failing, I haven't seen this in recent years and given the number of masts in circulation from companies like Moses its obvious that there is no problem here to solve by a 747 engineer ...and copying a good design is never been easy so big brands can/should/have copy best design and making mast is not rocket science ...common we are not talking about SpaceX here?

True no rocket science just a mast, hollow, foam-filled or not the only thing that matters is the result, stiff, strong, and light.

[omg]

Project Cedrus is the only hollow carbon mast on the market.

I respect and appreciate your enthusiasm, as I am also an Engineer, but you'd sell more product with full transparency and / or better market research:

https://www.aliexpress.com/item/32873647072.html

https://www.f-one.world/product/carbon-masts-3/

https://www.alibaba.com/product-detail/ ... bb26kuHjxk

Lift also makes a hollow carbon mast.

Duotone also make a hollow mast so that's at least 4 brands.

Any info on Duotone carbon masts and will they bring new front wings, please? Thanks!

[Jan:)]

Why would you want a hollow mast anyway?
For that volume the weight of a low density foam is basically zero.

What is that hollow section? 8mm*60mm?
For a 80cm mast, that would be 384cm3.
For EPS that would add up about 11g of weight.
Thats probably less than 1% of the overall weight.

I assume your mast is a great product.
So why try to focus on something that is practically meaningless?