Author Topic: Axis Foils  (Read 402995 times)

Phils

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Re: Axis Foils
« Reply #585 on: December 03, 2020, 05:13:53 AM »

..........

I ride 1/2” back in the tracks from my Armstrong setting.



.......

Would you say the Axis likes a bit more front foot pressure compared to the Armstrong or about the same?

Dwight (DW)

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Re: Axis Foils
« Reply #586 on: December 03, 2020, 05:58:39 AM »

..........

I ride 1/2” back in the tracks from my Armstrong setting.



.......

Would you say the Axis likes a bit more front foot pressure compared to the Armstrong or about the same?

I don’t ride any foils with front or rear foot pressure. I tune for perfect balance. If a company doesn’t make the parts to reach this level of tune, I dump it. Talking about you HA Lift
« Last Edit: December 03, 2020, 06:01:59 AM by Dwight (DW) »

Thatspec

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Re: Axis Foils
« Reply #587 on: December 03, 2020, 07:26:13 AM »
It's a beautiful piece of kit Admin, it took some doing to not buy your 76mm (80's my minimum). I'll probably buy an 86cm eventually but because I have a carbon fetish, not so much for reduced drag. Interestingly enough, the Axis 96cm carbon mast pees off the trailing edge roughly the same amount as the alu version(s). Can't say how that correlates with drag but logic dictates... 
Here it is after polishing off a few liters of German pilsner  ;D

https://gleiten.tv/index.php/video/action/view/v/3617/page/497/

 

Admin

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Re: Axis Foils
« Reply #588 on: December 03, 2020, 07:33:17 AM »
He had me at Shcleudlefon Axis.  :)

It think you will appreciate the reduced drag as well.  Don't get me wrong, I am not saying that mast drag is the only issue.  Drag is death by 1000 cuts.  Reducing everywhere you can makes sense.
« Last Edit: December 03, 2020, 07:41:59 AM by Admin »

Admin

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Re: Axis Foils
« Reply #589 on: December 03, 2020, 07:50:49 AM »
I don’t ride any foils with front or rear foot pressure. I tune for perfect balance. If a company doesn’t make the parts to reach this level of tune, I dump it. Talking about you HA Lift

I tried the 390 tail yesterday with the shim.  It has been a while since I swam that much.  I couldn't do anything.  Hobby horsing and a complete kookfest.  That combo is right out for me.  It was damn cold and not a great day to be counting salmon.  I drove home in my suit :).

flkiter

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Re: Axis Foils
« Reply #590 on: December 03, 2020, 08:39:20 AM »
I feel the 390 rear is great if you're a heavy rear foot rider. If you're more balanced and don't pump the board much then the flat wings like 460/420 and if you're more front foot pressure and pump the board a lot then the 340/370/400 rears work best. Just an observation I've seen with different riders and their stances when I try other people's set ups. Now throw in shimming and it's a whole different can of worms.

PonoBill

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Re: Axis Foils
« Reply #591 on: December 03, 2020, 08:45:13 AM »
This is a TV antenna?  Nah, this is as streamlined as it gets.  The connections are beautiful. 

Also, if 3mm is no big deal then just add 3mm.  We will all have chubby 22 mm masts and we can have a stiffy party.  Wait, that doesn't sound good on any level.

Interestingly (not for masts but just generally), if you play with the NASA calculator linked above you can see that increasing thickness by the 16% we have been talking about causes a significantly greater drag increase than increasing the angle of the same foil by 1 degree.  These new Black fuses allow for both thinner foils and lower angles so we are noticing that goodness as well. 



I'd buy that the mast to plate/fuselage connections are draggy and the carbon mast improves that substantially. The board to mast connection only matter when you aren't up on the foil and that's all low speed stuff. But even as pretty as the general design of Axis foil systems are, it's going to have a lot of drag from imperfect connections. When we're up on foil the mast is mostly out of the water. Even if it weren't the drag from the wings and fuselage are huge. It's lifting at least 200 pounds (unless it's Chan or a little kid). Lift and drag are directly related and as impossible to improve beyond that fundamental relationship as entropy in a heat engine. I'll play with the NASA toy, but ten or so inches of mast drag has to be a fart in a hurricane unless the mast is thick enough to separate flow as the cross section converges.
« Last Edit: December 03, 2020, 08:57:25 AM 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.

PonoBill

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Re: Axis Foils
« Reply #592 on: December 03, 2020, 08:56:03 AM »
For some reason, axis likes to set the incidence angle at about five degrees or more. That inevitably will require front foot pressure. That's five degrees of up elevator. Shimming that down to something between 2 and three degrees means you'll need to work a bit to get off the water, but once you're up you won't hobby-horse.

If you're moving the foil on the board and you don't have footstraps I have to wonder why. It won't eliminate the up elevator, it just lets you stand in your usual spot instead of shuffling forward. If you don't want to move your straps or change the foot position you're used to then sure, that's how to do it. Or you can shim down the incidence angle, in which case you'll have to move your feet back or move the foil forward.

I think the main reason a lot of foilers can't move their front foot is incidence angle. the constant front foot pressure required to counter the up elevator means you can't move your front foot until you move your rear foot forward, and that pitches the foil down. The more relaxed position with feet closer together will help, but tuning the foil to the minimum incidence angle needed for a stable ride helps more.
« Last Edit: December 03, 2020, 09:04:33 AM 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.

Dwight (DW)

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Re: Axis Foils
« Reply #593 on: December 03, 2020, 09:08:23 AM »
It’s more complex than just moving around and shimming stuff.

You need perfection (matching low drag wings) to have equal foot pressure throughout the foils speed range.

It’s easy to get equal pressure for part of it’s range. That’s not good enough for me.

deja vu

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Re: Axis Foils
« Reply #594 on: December 03, 2020, 09:09:22 AM »
I don’t ride any foils with front or rear foot pressure. I tune for perfect balance. If a company doesn’t make the parts to reach this level of tune, I dump it. Talking about you HA Lift

I'm assuming that you find the "perfect" balance point for the average wind conditions you're riding in and shift your weight either slightly forward in gusts and slightly aft in lulls.  In other words, you find the Axis foils easier to tune for that initial "perfect" balance point for steady winds and then you compensate as needed for gusts and lulls as your speed changes (which changes lift)?

I've never been able to obtain "perfect" balance with a foil for the variable wind conditions in which I wind foil and wing foil.  I'm unfortunately having to constantly compensate to changing wind conditions by shifting my weight forward or aft -- sometimes a little and sometimes quite a bit.  If Axis foils can be "perfectly" balanced for variable winds then it's time for me to change foils!

How hydrofoils work:

https://www.youtube.com/watch?v=fX-r0COL-xA
« Last Edit: December 03, 2020, 09:16:40 AM by deja vu »

Dwight (DW)

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Re: Axis Foils
« Reply #595 on: December 03, 2020, 09:54:54 AM »
You can find perfection. The HPS with 420 tail matches with 980 and 1050 perfectly throughout the speed range. I had similar perfect balance with my Armstrong throughout its speed range. But Armstrong could not match the HPS in glide, pump, or speed.

Mike dubs

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Re: Axis Foils
« Reply #596 on: December 03, 2020, 10:19:29 AM »
Ok so I’ve pulled the trigger on the 980. What stabilisers do I need to get for my choppy conditions? I’m 76kg, the 390 gap or 420/400? Max speed isn’t my priority, control and glide is.

Mike

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Re: Axis Foils
« Reply #597 on: December 03, 2020, 10:48:30 AM »
I feel the 390 rear is great if you're a heavy rear foot rider. If you're more balanced and don't pump the board much then the flat wings like 460/420 and if you're more front foot pressure and pump the board a lot then the 340/370/400 rears work best. Just an observation I've seen with different riders and their stances when I try other people's set ups. Now throw in shimming and it's a whole different can of worms.

Hey Nick,

Are you riding with a shim?  So far my favorite is the 390 with no shim and 420 with no shim.  Those both feel really good (I still need to check out the 420 on a decent day).  It was little off with the 420 and a shim and uncomfortable with the 390 and shim.  I used to have too wide a stance.  I was heavy on the rear foot at that point.  Late summer that rear foot started to feel comfortable further forward and it helped balance me out a lot.
« Last Edit: December 03, 2020, 10:51:41 AM by Admin »

flkiter

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Re: Axis Foils
« Reply #598 on: December 03, 2020, 11:14:03 AM »
I'm on the 370 rear with shim using the ultra short fuselage. I find a lot of times I have to slow down due to the different swells and wind chop and without the shim I wasn't feeling stable at slow speeds. I need to try it on the short fuselage but I've been on the 1050 and loving it so much that is hard to switch foils with the winds I'm having right now.

Dwight (DW)

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Re: Axis Foils
« Reply #599 on: December 03, 2020, 01:24:08 PM »
Ok so I’ve pulled the trigger on the 980. What stabilisers do I need to get for my choppy conditions? I’m 76kg, the 390 gap or 420/400? Max speed isn’t my priority, control and glide is.

Mike

420

Think about what makes the HPS so special. LOW DRAG. It’s the key to making performance. The 420 is the lowest drag tail.
« Last Edit: December 03, 2020, 01:27:12 PM by Dwight (DW) »

 


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