Forums > Kitesurfing Foiling

Humming foils

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Created by pearl Sunday, 15 Apr 2018
pearl
NSW, 953 posts
Sunday , 15 Apr 2018 6:30AM
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Hi. Any tips on the procedure to get rid of a humming foil; and what to use. It's a full carbon go foil. I can't feel any beads or marks on trailing edge of foil or mast. It's squared off from factory.
Was speaking to a guy who had his foil bitten by a shark. It hummed badly and he believes it attracts them. I had a shark I could stand on right under me while laying in water. It was first use with this one; so even if he is only slightly correct it would be good to get rid of the noise. Ta

warwickl
NSW, 886 posts
Sunday , 15 Apr 2018 11:03AM
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Try a thin shim (milk bottle plastic) under back screw of back wing to very slightly raise the back of the wing.
Plus I did a lot of 1200 wet and dry sanding of wings and fuselage.
It worked for my KFA carbon foil.

Kamikuza
QLD, 3070 posts
Sunday , 15 Apr 2018 2:19PM
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Threads at KF about it again. Suggestions include slightly squaring off the TEs, filling the pin marks surface holes and smoothing out, rough sanding to scuff the surfaces...

My personal observations: perfectly silent foils with "hum" when loaded up and going fast, ie. hard fast carves from toe to heel. I wonder if the gaps at the joins between the components aren't setting up an oscillation. Tighter fitting components with more "streamlining" seem to be far less prone to it...

pearl
NSW, 953 posts
Sunday , 15 Apr 2018 5:27PM
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Rear foil hammers in tight with single screw so don't think I can shim. Each mast is supposedly custom fitted to individual wings and can not be interchanged.



Kami you may be correct. It's a poor connect streamline wise from front wing to mast. I have dulled sharp edges and given trailing edges a light sand.
I tried a light sand on trailing edges of wings yesterday but it still hummed badly. Maybe even worse unless I was just going faster. Another shark; only a small one today. I'm thinking his theory is correct about attracting them.
Thanks for ideas. Kind of disappointed when you spend that amount of coin.

warwickl
NSW, 886 posts
Sunday , 15 Apr 2018 5:46PM
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Love the red wings but only if quite.
I have also on some points eg screw heads etc smoothed surfaces with board wax.
How tight is the slide on wing fittings, if a little loose maybe pack a bit.
Also ask the manufacturer. All my foils are surperbly quite and vibration free these days.
Only the rider needs a lot of improvement.

Kamikuza
QLD, 3070 posts
Sunday , 15 Apr 2018 7:03PM
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My LF FF had a very quiet whistle when doing heel side carves.

Same with the old Naish foil.

I don't remember a noise from the Hoverglide, and that fitted even more clunkier than the LF or your Go.

The DA I used in Japan had a constant medium-loud "hoo" when it was at foiling speed, but the one I rode in NZ was completely silent.

Guy with Alpine Access foil has a constant very loud whistle the can be heard for hundreds of meters; by far the loudest foil I've encountered. The Access I rode (different foil) was silent.

My Axis foil was completely silent, except for a small momentary squeak (like cork on glass) when heel side carving, at the point of max load and speed. The SUP foil was completely silent at all times.

...different gear, different designs; some whistle, some don't. Who knows why

TomW059
169 posts
Tuesday , 17 Apr 2018 4:12AM
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I had some hum from my moses 590 wing. None at all from same set up with 550 front wing. I painted it with primer and wetsanded it with 800g. No hum.
I think it was some pin holes in the finish....

alverstone
WA, 443 posts
Yesterday , 19 Apr 2018 1:07PM
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Select to expand quote
pearl said..
Hi. Any tips on the procedure to get rid of a humming foil; and what to use. It's a full carbon go foil. I can't feel any beads or marks on trailing edge of foil or mast. It's squared off from factory.
Was speaking to a guy who had his foil bitten by a shark. It hummed badly and he believes it attracts them. I had a shark I could stand on right under me while laying in water. It was first use with this one; so even if he is only slightly correct it would be good to get rid of the noise. Ta


Get earplugs ... .

Just kidding, but given my Zeeko B&W hums, this thread will make me explore options suggested, in particular the rear foil shim.

However, I've clunked it so many times this could be a fool's errand.

Maybe it will be best to use earplugs. At least they'll stop the wind noise from my helmet's ear pieces ....

Lambie
VIC, 678 posts
Yesterday , 19 Apr 2018 7:11PM
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Noise comes from vibrations, and when it comes to laminar flow vibrations equals inefficiencies. Vibrations are caused by unequal pressures.

Is it important ? For me where Im not looking for warp speed Im not fussed - but if I found the sound annoying Id be looking to findout why its happening!

RAL INN
VIC, 2368 posts
Yesterday , 19 Apr 2018 7:33PM
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Lambie said..
Noise comes from vibrations, and when it comes to laminar flow vibrations equals inefficiencies. Vibrations are caused by unequal pressures.

Is it important ? For me where Im not looking for warp speed Im not fussed - but if I found the sound annoying Id be looking to findout why its happening!


When you hear it.
it means you are going fast enough and with enough control to relax your brain enough to let in that extra neural input.
pump the air, hoot out loud, then get on with the progress.

Gorgo
VIC, 3902 posts
Yesterday , 19 Apr 2018 9:04PM
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Take some ultra close up photos of the wing edges. I have seen tiny voids in the edges that you can't see with the naked eye.

If they are there, rub in some epoxy putty, sand, paint and sand again and the noise will be eliminated or reduced.

dafish
NSW, 1192 posts
7 hours ago , 19 Apr 2018 11:34PM
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Select to expand quote
Lambie said..
Noise comes from vibrations, and when it comes to laminar flow vibrations equals inefficiencies. Vibrations are caused by unequal pressures.

Is it important ? For me where Im not looking for warp speed Im not fussed - but if I found the sound annoying Id be looking to findout why its happening!


Yup. When I first switched over to the Spitfire XLW it was singing like crazy. Friends on the beach could hear it. Once I learned were the COG was it went away. Whenever I hear it now I know that I am not being very efficient with the foil. Saying that, I have heard other foils that sing regardless of where the rider is on the wing and that would require all the techniques that others have mentioned to quiet the noise.



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"Humming foils" started by pearl