Author Topic: Getting ejected out the front door...  (Read 5291 times)

Beasho

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Re: Getting ejected out the front door...
« Reply #15 on: October 26, 2021, 12:09:32 PM »
Waxing, sanding, foil shape . . 'we' all went crazy with this in the 90's with windsurfing fins.

With regards to speeds.  I measured the heck out of Surfboard speeds, and foil speeds.  Hundreds of thousands of data points.  My take is this:

1) Winging is relatively SLOW:  Speeds from 7 mph to 18 mph.  More advance wingers are faster.  Johnny Heineken goes 26 mph.   
2) SUP foiling on waves gets faster.  Slow ~ 10 mph.  Fast 20 mph.  Blistering is 25 mph.  BUT the speed is nearly perfectly correlated to wave size.  To go 25 mph you'll need a 10 foot wave or bigger. (not counting a Pipeline type wave which does change/increase the math slightly)
3) A surfboard, or SUP, on an 18 foot wave can hit 30 mph.  To get to 35 mph Mavericks will deliver. 
4) Old school shortboard Windsurfer would plane at 17 mph. (as measured by Speedwatch) FAST was 25 mph.  30 mph was almost unobtainable due to CHOP and required wind speed, flat water . . . hence the world record was in the 30's for a while
5) Kite foils apparently blow this all away (I do not have data).  But 30 mph is supposed to be reasonable for a good kite-foiler.

Winging will get faster.  I will get faster.  Winging will likely converge with Kite foil speeds but we will lose the comfort and sanity of controlled slow speed flight.

PS: My first session on the Axis999, in winds blowing 30 to 40 mph in flat protected water, I recorded speeds of 11 to 13 mph.  Maxed out at 13.4 mph.  And I was OK with this, way overpowered on a 5.0.  But I wasn't ripping past 20 mph on my first session.  For the record I have never knowingly ventilated my mast.
« Last Edit: October 26, 2021, 12:18:43 PM by Beasho »

bigmtn

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Re: Getting ejected out the front door...
« Reply #16 on: October 26, 2021, 02:28:40 PM »
According to my phone my top speeds per session usually range between 22 - 26 mph.

28.07mph is fastest I've recorded.

Measured using windsport tracker app, who knows how accurate it is.

PonoBill

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Re: Getting ejected out the front door...
« Reply #17 on: October 26, 2021, 03:32:08 PM »
You are a bit less likely to ventilate surfing, no matter how fast you go. You are more likely to be vertical and the force that's pushing you through the water is being applied down low, partly to the foil, and to a lesser degree from gravity shoving you down the face of the wave. The amateur physicist in me recoils at saying anything that sounds like "the force of gravity" but don't worry, I'll be okay, I just need to lie down in a dark room for a moment.

At first glance, you might think the speed of the foil through the water is less because the foil is moving at wave speed or thereabouts. But the water doesn't move with the wave. It basically just moves up and down in a little epicycle.

If you fully ventilate your mast you will definitely know it. The wing gets surrounded by a bubble of air. Air is about 1000 times less dense than water. You'll have just about as much lift remaining as you will if you hold the 999 over your head and run down the beach making propeller sounds.

« Last Edit: October 26, 2021, 03:36:36 PM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

Solent Foiler

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Re: Getting ejected out the front door...
« Reply #18 on: October 28, 2021, 03:24:18 AM »
Just to be clear, I'm not chasing high speed, I'm just trying to get upwind as quickly as possible to ride downwind again, so might as well make it fun by pushing as hard as I can, having a harness and all. I don't even record my sessions so have no idea how fast I'm actually going.

But that's sort of the point. I think I'm operating in a fairly conservative envelope when it comes to speed/performance (the 999 is not a speed foil in the grand scheme), so why should I be suffering from this ventilation issue? I'm only 65kg, so can't be loading up my kit as much as bigger riders...

But, I may have found a technique issue yesterday that might be making the problem worse. When I go upwind I normally have my back foot out the strap - it's just more comfortable as I can control the pitch and roll a bit more easily when just blasting in a straight line. I need to take it out for tacking anyway as I swap feet so one less thing to do. If I go upwind with my back foot in the strap, it feels a lot less likely to ventilate and if it does, it's less dramatic and correcting is easier.

I wonder if that stance is giving me more yaw control, so can keep the mast pointing in the direction of travel better than having my back foot forward? Or perhaps just being more central over the mast is asking it to work less hard as a lifting surface? Whatever, will continue to experiment...
I'm 5'10", 65kg riding:
Gong Lethal 4'6 65L
Gong Catch 5'3 34L
Gong Hipe v2 4'11 70L
Axis ART 999
Gong Fluid L-S, XXL-S on 85cm mast
Duotone Slick 3m, 4m, 5m

WingTime

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Re: Getting ejected out the front door...
« Reply #19 on: October 30, 2021, 07:15:39 PM »
Lots of good discussions here, thanks to all,
I have used a nano coating on my aluminum mast , I can tell the difference but have to reapply
Today I had the 999 on a cedrus project mast , lighter than most carbon masted and I really like the feel. As for mast ventilation, Iím not sure if itís better or worst will be paying more attention to this in my next session.

dns

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Re: Getting ejected out the front door...
« Reply #20 on: October 31, 2021, 10:06:40 AM »

I have used a nano coating on my aluminum mast , I can tell the difference but have to reapply


FWIW I was just working with a guy that's super into kite foil racing. He said they're all going to super polishing their masts and wings (2000-3000 grit) then roughing up the first third or so with 600 grit. Then cleaning with Windex before a race.

SUPeter

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Re: Getting ejected out the front door...
« Reply #21 on: November 02, 2021, 08:43:41 AM »
Got the 999 up to 20 mph using a 19mm(90cm) mast on multiple occasions and ventilated the mast only  a couple times so far.  That is extraordinarily good performance from my standpoint having only used homemade masts.  The ventilations are also shorter lived events which are usually recoverable as soon as the edge of the board drops to the surface I pop right back up and keep on pushing.  Having the mast at such high angles makes it much like a wing in that at certain times there will be positive pressure on one side and negative pressure on the other.  Add to this a constant access to the waters surface and voila, air is sucked down to the business end.

PonoBill

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Re: Getting ejected out the front door...
« Reply #22 on: November 02, 2021, 11:47:40 AM »
yup. I think the amount of yaw in your ride makes a difference too. Most people complaining about ventilation experience it going hard upwind, when the mast is acting like a wing with one tip out of the water. The symmetrical shape minimizes the differential pressure across the mast until you add a bit of yaw, which results in an increase in AOA with the upper surface of the mast getting more separated flow. I notice that people riding with front and back footstraps can hold a tighter reach than those who ride strapless. They might be just better foilers, but they also might be cranking in a bit more yaw and gaining lift, like a cranked over sailboat gets from its keel when the skipper adds a little yaw with the rudder.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

Alysum

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Re: Getting ejected out the front door...
« Reply #23 on: November 02, 2021, 08:10:18 PM »
I'm glad I found this topic and that it's not just me experiencing regular "spin outs" on my Axis foils.

There is a long discussion on Facebook: https://www.facebook.com/groups/axisfoilriders/posts/553983515699944

Yesterday I went kitefoiling on my carbon 86 with ultrashort and 700/380 wings. Water was quite choppy.
In 2h I ventilated a total of 10 times with 7 of those resulting into a spin out and heavy crash  :-[

I also experience spin outs when winging but it seems to be less frequent than under a kite. Happened using my 830 and 999 wings too.

It doesn't happen just at high speeds, it's happened to me a low speeds as well. One possible way to explain this is the foil being more under water where the tapered carbon mast is thicker...

Ventilation is reduced with a thinner and stiff mast plus long chord according to Kyle@Cedrus.

I wouldn't exclude that it's the foils design rather than the mast design. I ride the 380 stab 90% of the time so I wouldn't exclude the winglets having a play in this. I do recall a spin out but less severe, using the progressive 400 stab.

The mystery continues....
« Last Edit: November 02, 2021, 08:50:40 PM by Alysum »

Solent Foiler

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Re: Getting ejected out the front door...
« Reply #24 on: November 03, 2021, 01:36:10 AM »
There is a long discussion on Facebook: https://www.facebook.com/groups/axisfoilriders/posts/553983515699944

Thanks for that link - loads of good info there. Food for thought!

Currently pondering one of two options - trying the 16mm Axis mast or get my (currently cracked) Gong carbon mast that I know doesn't suffer from ventilation as far as I know mended and modified to accept the Axis fuse...
I'm 5'10", 65kg riding:
Gong Lethal 4'6 65L
Gong Catch 5'3 34L
Gong Hipe v2 4'11 70L
Axis ART 999
Gong Fluid L-S, XXL-S on 85cm mast
Duotone Slick 3m, 4m, 5m

Alysum

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Re: Getting ejected out the front door...
« Reply #25 on: November 08, 2021, 01:54:54 AM »

Solent Foiler

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Re: Getting ejected out the front door...
« Reply #26 on: November 08, 2021, 03:48:33 AM »
Glad it's not just my clumsy riding then, although the real reason is still unappealing - a design issue.
My Gong carbon mast is at my local boat builder/repairer getting modified this week hopefully. Just in time for a week of high pressure and little wind...
I'm 5'10", 65kg riding:
Gong Lethal 4'6 65L
Gong Catch 5'3 34L
Gong Hipe v2 4'11 70L
Axis ART 999
Gong Fluid L-S, XXL-S on 85cm mast
Duotone Slick 3m, 4m, 5m

Califoilia

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Re: Getting ejected out the front door...
« Reply #27 on: November 08, 2021, 10:24:28 AM »
Another long post on FB on the same issue https://www.facebook.com/groups/axisfoilriders/permalink/565139107917718/
I'm not on Facebook, and wondering if you can get a screen shot of a couple of the post there wrt the issue if possible. TIA
Me: 6'1"/185...5'1" Kings Foil Board...5'7" Kings Foil Board...9'6" Bob Pearson "Laird Noserider"...14' Lahui Kai "Manta"...8'0" WaveStorm if/when the proning urges still hit.

Alysum

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Re: Getting ejected out the front door...
« Reply #28 on: November 09, 2021, 02:10:53 AM »

Beasho

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Re: Getting ejected out the front door...
« Reply #29 on: November 09, 2021, 06:27:09 AM »
Is what we are talking about good ole' fashion windsurfing

SPIN OUT

Those of us with a windsurfing background know Spin Out to be a function of going fast and loading up a fin on a choppy, or aerated, surface. 

We have been fighting it for decades. 

 


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