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Unboxing: Moses Aluminium Foil Kit

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kitexpert
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Re: Unboxing: Moses Aluminium Foil Kit

Postby kitexpert » Thu Jul 25, 2019 9:46 pm

tomtom wrote:
Thu Jul 25, 2019 7:25 pm

In hydrofoil mast almost all that matters is stiffness. This structure has defined thickness - So what define it stiffness is young modulus of material. Normal woven CF composite has ca. 70 Gpa and significantly less than that in any other than 0 and 90 direction. UD have 135 GPA but only 10 Gpa perpendicular to fibers. So we can assume that mean YM for carbon composite in Foil mast is in 50 Gpa range.
No, hf mast structure does not have any defined parameters - only cheap extrusion alu masts do. You can and you should vary both chord length and profile thickness according to existing forces, this is of course only possible with composite masts.

Your assuming "mean YM" for carbon composite makes no sense because hf builders aren't idiots. In reality they think carefully fiber orientations. Mast is a simple shape itself, so it is not difficult to achieve very good fiber/resin relation in the structure. Pre-pregs or HM fibers could only improve stiffness marginally. Heat curing is easily done.

If really stiff mast is needed it just have to be slightly thicker. For usual freeride use then marginally increased drag is insignificant.
tomtom wrote:
Thu Jul 25, 2019 7:25 pm

Aluminum alloy have 72 GPA /and this 72 GPA is 72 gpa in all direction/ - and its death easy to made it repeatably good with internal I beams. Usually it has also much thicker wall because alu is much weaker /ultimate strength not stiffness/ So you end up with stiffer alu mast much easier than carbon.
Yes, it is easy to order alu masts after molds for extrusion are available somewhere. Manufacturing costs are of course very low, and result is quite stiff and heavy mast. Or you can have stiffer light weight mast in carbon, but it is not cheap. After getting used to light carbon equipment heavy aluminium feels so cheap.
tomtom wrote:
Thu Jul 25, 2019 7:25 pm
To made carbon as stiff as alu you must use UHD carbon and either solid mast /no weight advantage to alu/ or with carbon internal I beams and very hi end technology /prepreg and autoclave/ So far it is very hard to make carbon mast as stiff as alu.
Wrong, wrong, wrong. Apparently you don't know much about working with carbon and you don't know what is possible.
tomtom wrote:
Thu Jul 25, 2019 7:25 pm

One cheap method can be use of hardwood or bamboo core but it is quite hard adapt it for mass production.
Core is not at all important for the stiffness, as long as structure does not collapse under strain. All sporting equipment which need highest possible stiffness/weight ratio are hollow and they are essentially carbon composites. Simple hf mast is no exception.

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Re: Unboxing: Moses Aluminium Foil Kit

Postby tomtom » Thu Jul 25, 2019 9:55 pm

Not only kiteexpert but also mastexpert
These users thanked the author tomtom for the post (total 2):
jumptheshark (Fri Jul 26, 2019 12:21 am) • kitexpert (Fri Jul 26, 2019 11:21 am)
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Kamikuza
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Re: Unboxing: Moses Aluminium Foil Kit

Postby Kamikuza » Fri Jul 26, 2019 11:50 am

tomtom wrote:
Thu Jul 25, 2019 9:55 pm
Not only kiteexpert but also mastexpert
You mean of course, strutexpert

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Re: Unboxing: Moses Aluminium Foil Kit

Postby kostantin » Fri Jul 26, 2019 4:46 pm

Kamikuza wrote:
Fri Jul 26, 2019 11:50 am
tomtom wrote:
Thu Jul 25, 2019 9:55 pm
Not only kiteexpert but also mastexpert
You mean of course, strutexpert
Expert sounds ok for me. Love or hate it, he hit the nail.

tks

Kosta

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Re: Unboxing: Moses Aluminium Foil Kit

Postby tomtom » Fri Jul 26, 2019 5:35 pm

Sound ok for you because it resonate with your believes.

Anyway

Most alu mast are stiffer than most carbon masts - that is simple fact. For torsion they are virtually always stiffer.

If you somehow manage made hollow mast from standard carbon which is actually stiffer than alu /same profile thickness of course/ in both bend and twist
then you are composite manufacture genius.
About fibre orientation - kiteexpert you are kidding yourself. - How you orientate fibre on places where you need strength in all directions? /most places in mast/
And of course you can make mast thicker for more stiffness but that is so death obvious that i wasnt even mention it. So I always assume same profile thickness.

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Re: Unboxing: Moses Aluminium Foil Kit

Postby bricedenice » Fri Jul 26, 2019 11:17 pm

I'd be more worried about the plate to mast connection. "Very little play" is different than "no play", which is what any decent setup should aim for.

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Re: Unboxing: Moses Aluminium Foil Kit

Postby tomtom » Sat Jul 27, 2019 12:38 am

Sure. Thats is a must

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Re: Unboxing: Moses Aluminium Foil Kit

Postby knotwindy » Sat Jul 27, 2019 2:38 am

bricedenice wrote:
Fri Jul 26, 2019 11:17 pm
I'd be more worried about the plate to mast connection. "Very little play" is different than "no play", which is what any decent setup should aim for.
Or just one piece, no play at all. :bye:

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Re: Unboxing: Moses Aluminium Foil Kit

Postby Flyboy » Sun Aug 18, 2019 9:55 pm

Yes - just compared my carbon mast to my aluminum mast. No question that the aluminum strut itself is much stiffer. The carbon mast has an integrated base plate & firmer fuselage/mast wing connection however.

Not sure what the relative effects are on performance of light weight vs stiffness. This might vary depending on the kind of wings used, the length of the mast & the kind of conditions/kind of riding?
Last edited by Flyboy on Mon Aug 19, 2019 5:56 am, edited 1 time in total.

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Re: Unboxing: Moses Aluminium Foil Kit

Postby kitexpert » Sun Aug 18, 2019 11:04 pm

If weight doesn't matter steel is very stiff material, about three times as stiff as aluminum. But IDK if it makes very much sense to compare light weight carbon masts to heavy alu masts (which may also be thicker) or even less to steel masts.

On the other hand if someone would make a carbon mast which is as heavy as aluminum mast it would be extremely stiff if fiber layout and manufacture was decent.

My custom set weighs about 5kg (hf+board) and it has a good ride and it is not PITA to carry. No way I wouldn't change it to heavy alu set even if it had a stiffer mast.


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