Author Topic: Foil whistle  (Read 999 times)

frenchfoiler

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Foil whistle
« on: October 11, 2018, 01:13:08 PM »
Does anybody know why my Go Foil whistle ?

It is a brand new one, the one I had before (same) didn't do it.

Any explanation ?


Thanks.

Dwight (DW)

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Re: Foil whistle
« Reply #1 on: October 11, 2018, 01:33:07 PM »
Naish issued a tech bulletin on how to sand foils to stop it. But they took it down pretty quick after publishing. Asking for trouble.....telling kooks how to sand their wings!

It said, sand trailing edge (top edge only) at 45 degree angle for front wing.

For rear wing, do the opposite. Sand trailing edge (bottom edge only) 45 degrees.

None of their 2018 wings made noise. All the 2019s Iíve ridden made noise.

SURFFOILS

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Re: Foil whistle
« Reply #2 on: October 11, 2018, 02:30:35 PM »
Foils whistle because they donít know the words.
Dad joke.

Is it a whistle, a hum and is there any vibration ? Did you check the mast ?
« Last Edit: October 11, 2018, 02:34:48 PM by SURFFOILS »

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Re: Foil whistle
« Reply #3 on: October 11, 2018, 05:41:54 PM »
its the perfect slightly square trailing edges, you can either sand/file/gouge them up to stop it (most NZ built yachts have a small 45* bevel on the rudder trailing edge to stop this) or just embrace the music, it sounds awesome and doesnt affect the performance in any noticeable way. i never had a whistle on my foils cause i kept the trailing edges rough and razor sharp, until i molded a gofoil tail wing and now i get the whistle.

at one stage in the name of experimentation i went as far as notching the front wing and the mast, ever seen any wings in nature with a fair, symmetrical trailing edge? nope

norcom

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Re: Foil whistle
« Reply #4 on: October 12, 2018, 08:02:28 PM »
I have two sets of GoFoils one with Iwa/Maliko big blue tail and one with Kai and small red tail. They all hum and whistle like CRAZY! The Kai is so loud that I feel embarrassed I may be bothering people on the beach a quarter mile out. I sanded the rears flat and it alleviated some of the noise but nowhere near enough. Strangely certain constant speeds and AOA on different wings reduce the noise. I haven't touched the front wings because removing them requires a mallet. I just try to ignore it, which is VERY hard for me as noises drive me mad! I've tore down and rebuilt my mountain bikes MANY times to find a creak then to find out it was a simple zip-tie rubbing on a weird place or something.

I primarily kite/wind surf these wings so I donít get a chance to ignore the noise while not on a foil. Thereís a few threads on kiteforum and seabreeze regarding the issue. Itís not a simple fix but it can be done.   

Beasho

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Re: Foil whistle
« Reply #5 on: October 13, 2018, 05:12:30 AM »
I love all this "VooDoo Magic" BUT I did have good success sanding 1/2 the TRAILING edge of my Tail-Wing.

Specifically I did the "Good" method shown below.  I had put the KAI tailwing on my IWA front wing and it was Whistling like crazy.  This 10 minute trick reduced the sound by 80%+.

Humming comes from Vibration.  Vibration is the result of a wobbling airfoil.  All Airfoils naturally wobble just like a FLAG flaps in the breeze.  On an airplane the fuselage dampens the oscillation when combined with a stiff wing.

PS: My foil amigo Haley has been trying to train the proners at his local spot.  He leverages the humm as intimidation.  But everyone knows him as a big-wave, successful, immortal nut.  Specifically he is trying to show them that they can take off deep, and he wide, and that 2 people can successfully and with NO, read ZERO, impact to each-other's enjoyment ride the same wave. 

From here:  http://www.farriermarine.com/pdf/Hints.pdf     
« Last Edit: October 13, 2018, 05:17:46 AM by Beasho »

Beasho

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Re: Foil whistle
« Reply #6 on: October 13, 2018, 05:23:53 AM »
Here is some more VooDoo.  However this magician has been at it longer than most.

This was from Alex Aguerra himself posted on SeaBreeze:

"Here is what I do, I sand the last one inch of the trailing edges of the wings top and bottom. You need a clean release that is more like a   concave away from the edge and not rounded at the edge. Most   humming comes from the last 1/4" at the edge rounded to the edge.   You want to get rid of that and get it a bit thinner and almost concave going the other way.
 
If you are good with tools, take a 5" orbital sander with 60 grit and try to sand it with sander up on its side a little and point load it about 1"   away from the edge and start sanding there and slowly get to the   edge. Do not start at the edge! Slowly get there by taking away meat   one inch away.  Once done, go down to 150 grit and smooth it. then you can repaint  with a sandable primer and then go to red or blue after that if you   want.  Put wings in the light (side ways like a shaping light) to see if you can see a rounded trailing release. If you switch wings like your tail wings   and one makes noise and one doesn't, you can narrow down which one is making the noise.  Sometimes it can be both.  Last thing is to square off the trailing edge with a block, perpendicular to the edge, try not to let the edge get super sharp or you can cut   yourself but a thinner trailing edge is usually quiet if sanded correctly. You can call me if you want me to explain more in detail Aloha.Ē 

AA
 

PonoBill

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Re: Foil whistle
« Reply #7 on: October 13, 2018, 09:41:40 AM »
I hot-glued two thin washers to the outside bottom edge of my M200 because the hum was driving me nuts. That turned it off like a switch, but I missed it, so I took them off.
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frenchfoiler

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Re: Foil whistle
« Reply #8 on: November 11, 2018, 02:50:44 PM »
I love all this "VooDoo Magic" BUT I did have good success sanding 1/2 the TRAILING edge of my Tail-Wing.

Specifically I did the "Good" method shown below.  I had put the KAI tailwing on my IWA front wing and it was Whistling like crazy.  This 10 minute trick reduced the sound by 80%+.

Humming comes from Vibration.  Vibration is the result of a wobbling airfoil.  All Airfoils naturally wobble just like a FLAG flaps in the breeze.  On an airplane the fuselage dampens the oscillation when combined with a stiff wing.

PS: My foil amigo Haley has been trying to train the proners at his local spot.  He leverages the humm as intimidation.  But everyone knows him as a big-wave, successful, immortal nut.  Specifically he is trying to show them that they can take off deep, and he wide, and that 2 people can successfully and with NO, read ZERO, impact to each-other's enjoyment ride the same wave. 

From here:  http://www.farriermarine.com/pdf/Hints.pdf   

What do you do then ? do you leave it like that or you need to put something on it ?

surfcowboy

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Re: Foil whistle
« Reply #9 on: November 12, 2018, 06:37:53 PM »
Interesting that this canít be done at the factory. Also, is this not something that could be molded in or are the tolerances too tight?

clay

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Re: Foil whistle
« Reply #10 on: November 12, 2018, 09:05:44 PM »
My answer to this question is to testify that other foils I have flown do not whistle nor hum.   My gofoil original Maliko did hum. I flew a friend's kai that had been sanded/tuned/painted and it did not hum.
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