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Chipotle
Since 26 Mar 2011
70 Posts
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Wed May 30, 18 11:00 am |
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No offense taken. I have not found another hollow carbon production mast, can you share the info here? Every carbon foil I've ever personally seen and felt has been solid laminate: F-one, slingshot, LP, Mikes Lab, lift, F4. My slide might show only one carbon foil, but trust me I've benchmarked every product I can find info on and nothing is even close to 40% lighter than aluminum products, which they should be given the specific stiffness of carbon fiber (modulus/density) on a stiffness critical component, which a mast is.
I think I saw a picture of a home-built floating in Maui, but never found any info on it.
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wylieflyote
Since 30 Jun 2006
1646 Posts
Puget Sound & Wa. Coast
XTreme Poster
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Wed May 30, 18 11:36 am |
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That settles it. The only reason that my $1800 2017 Ghost Whisperer feels lighter than my $300 2018 LF Happy Mast is that I paid more money, so it better be lighter dammit
_________________ CGKA Member
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Kip Wylie |
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underwood
Since 26 May 2018
21 Posts
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Thu May 31, 18 5:25 am |
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Interesting discussion on mast...
What about wing size? Seems like there is a trend toward larger front wing (>750cm2) for freeride foils. Passing fad or are there real advantages ?
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consumer
Since 28 Nov 2010
406 Posts
banned
Obsessed
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Thu May 31, 18 5:35 am |
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Have you had any problems with cavitation with project cedrus? To achieve the level of strength you quote with a hollow carbon mast, it sounds like you made the mast very thick (19mm, the thickest of all the masts you have measured in your set).
I know that in 2018 the ghost whisper mast was made thinner because people complained of cavitation when the mast was angled in the water and ridden at high speed...
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Chipotle
Since 26 Mar 2011
70 Posts
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Thu May 31, 18 6:21 am |
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What people are referring to is actually called ventilation, not cavitation. My early prototypes did have a tendency to ventilate but it was not due to the thickness, it was caused by the discontinuity in the surface where the leading & trailing edges mate to the carbon. A little gap filler solved the problem.
Ventilation occurs when air is trapped on the low pressure side of the mast, which occurs at higher angles of attack. This bubble will build, and eventually releases. You can reduce the ventilation angle of onset by reducing your thickness OR increasing your chord length, but more importantly through proper section shape. You cannot blame simply the thickness.
Cavitation is the water literally boiling and that's another problem. I don't know any foilers who actually ride fast enough to boil the water behind them.
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eric
Since 13 Jan 2006
1831 Posts
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Thu May 31, 18 6:46 am |
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Super interesting discussion to me. So, would in theory an elliptical mast profile—continuous and differentiate everywhere—be free from this problem? Or not that simple?
Eric
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eric
Since 13 Jan 2006
1831 Posts
XTreme Poster
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Chipotle
Since 26 Mar 2011
70 Posts
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Thu May 31, 18 3:05 pm |
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That is super cool to see.
To answer your question, no it's not quite as simple as that:) Again, the separation angle (the angle at which the bubble will ventilate or flow will separate) is dependent on thickness, chord, and the profile/section shape. If you look at the below curves, flow will separate from this particular section shape with 19mm thickness and 130mm chord at 5 degrees, while a thinner mast at 18mm but also shorter chord at 100mm will potentially ventilate at half that angle (1.8 degrees). You could come up with an entirely different shape with those same specs that has lower drag, but also lower separation angles. It just depends on what you're trying to optimize for...
As a structural engineer I'll be the first to admit I'm no expert in fluid dynamics, hence why I don't make wings:) This data was generated by a friend who's designed foils for a living. Nothing beats empirical test data, but I'm simply trying to illustrate the general trends and relationships.
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Screen Shot 2018-05-31 at 4.05.49 PM.png |
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niknas
Since 18 Sep 2006
184 Posts
North of OR, South of WA
Stoked
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Thu May 31, 18 4:36 pm |
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underwood wrote: | Interesting discussion on mast...
What about wing size? Seems like there is a trend toward larger front wing (>750cm2) for freeride foils. Passing fad or are there real advantages ? |
I too am curious about wing size. As a free ride foiler riding 2015/16 Lift I would like a wing that is easy to keep on a plane when turning down a swell without out running it. I am a big guy at 190#.
I have heard great things about the Lift “surf” wing and the Naish large surf wing for go slow surf and swells. I am asking about the Lift and Naish because I have their standard kite foils. Any thoughts?
🤔🤔🤔
_________________ Current Underwood Cam |
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eric
Since 13 Jan 2006
1831 Posts
XTreme Poster
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Fri Jun 01, 18 7:48 am |
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I think high aspect wings will be dedicated for those who want to ride very fast, or jump very high, and/or are super skilled, whereas medium to low AR wings will be the bread and butter for the rest of us. I have a low AR wing and am loving it. I have a medium AR wing that I also love, but wan't to get some moves dialed on the low AR before switching back. I see myself repeating this cycle as I get motivated to practice new skills.
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underwood
Since 26 May 2018
21 Posts
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Fri Jun 01, 18 6:48 pm |
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The below video is a review of a larger foil intended for a SUP is being used as a kite foil, and if you believe the reviewer with great success.
Warning; the video promotes a specific brand...
https://www.youtube.com/watch?v=qWOKbDWZQtw&t=0s
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