Northwest Kiteboarding
Forum | Classifieds | Lost & Found | CGKA | Industry | Sensors | Forecast | Spots | Seattle | Decals | RSS | Facebook

Events | Photos | Search | Register | Profile | Log in to check your messages | Log in 

First Carbon Foil Reccomendations
Page Previous  1, 2
 
Post new topic   Reply to topic    Northwest Kiteboarding -> Gorge / Portland / Oregon Coast
previous topic :: next topic  
Author Message
Chipotle

Since 26 Mar 2011
62 Posts

 



PostWed May 30, 18 11:00 am     Reply with quote

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.

View user's profile Send private message
wylieflyote

Since 30 Jun 2006
1259 Posts
Puget Sound & Wa. Coast
XTreme Poster



PostWed May 30, 18 11:36 am     Reply with quote

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 Smile
_________________
CGKA Member
-------
Kip Wylie

View user's profile Send private message
underwood

Since 26 May 2018
12 Posts

 



PostThu May 31, 18 5:25 am     Reply with quote

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 ?

View user's profile Send private message
consumer

Since 28 Nov 2010
394 Posts
banned
Obsessed



PostThu May 31, 18 5:35 am     Reply with quote

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...

View user's profile Send private message
Chipotle

Since 26 Mar 2011
62 Posts

 



PostThu May 31, 18 6:21 am     Reply with quote

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.

View user's profile Send private message
eric

Since 13 Jan 2006
1309 Posts

XTreme Poster



PostThu May 31, 18 6:46 am     Reply with quote

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

_________________
I only kite if I am alone, or with somebody else.

GO BEARS!

View user's profile Send private message
eric

Since 13 Jan 2006
1309 Posts

XTreme Poster



PostThu May 31, 18 10:35 am     Reply with quote

Mast ventilation:
https://www.youtube.com/watch?v=0J0jaMIRMR0

Wing ventilation:
https://www.youtube.com/watch?v=NefnpuxS2uM

Kinda cool to see

Eric

_________________
I only kite if I am alone, or with somebody else.

GO BEARS!

View user's profile Send private message
Chipotle

Since 26 Mar 2011
62 Posts

 



PostThu May 31, 18 3:05 pm     Reply with quote

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.


   Screen Shot 2018-05-31 at 4.05.49 PM.png 

View user's profile Send private message
niknas

Since 18 Sep 2006
135 Posts
North of OR, South of WA
Stoked



PostThu May 31, 18 4:36 pm     Reply with quote

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 weather and Cam from Underwood WA

View user's profile Send private message
eric

Since 13 Jan 2006
1309 Posts

XTreme Poster



PostFri Jun 01, 18 7:48 am     Reply with quote

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.
_________________
I only kite if I am alone, or with somebody else.

GO BEARS!

View user's profile Send private message
underwood

Since 26 May 2018
12 Posts

 



PostFri Jun 01, 18 6:48 pm     Reply with quote

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

View user's profile Send private message
Post new topic   Reply to topic    Northwest Kiteboarding -> Gorge / Portland / Oregon Coast All times are GMT - 8 Hours
Page Previous  1, 2
Page 2 of 2

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You can attach files in this forum
You can download files in this forum