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Author Topic: Axis Foils  (Read 145425 times)

Admin

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Re: Axis Foils
« Reply #465 on: October 17, 2020, 12:43:15 AM »
Unless you are racing, in which case the thinner masts reduce drag. But this is a small population, which is why I developed Project Cedrus.

Hi Kyle,

I dig your design and I have witnessed guys who are loving your masts (and ripping on them).  Very cool!

I get what you are saying and, no doubt, weight and stiffness are 2 of the big 3 key mast factors (with drag being the 3rd).  I do think that extra 3 mm across the wetted length matters for winging.  That is drag that we all have (most of us not racing).  Less drag translates to early take offs, better glides and less stalling.  We see foil companies marketing on shaving of 1-2 mm of thickness on their new foils (and in a lot of cases that comes at the expense of lift which is not the case with a mast thickness reduction).  This is all part of that same drag equation. 

You had mentioned in another thread that you could do tapered masts using your design and construction, but that they could not be custom sized.  Did I get that right? 
« Last Edit: October 17, 2020, 01:02:28 AM by Admin »

Phils

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Re: Axis Foils
« Reply #466 on: October 17, 2020, 01:41:31 AM »
Pretty much all the carbon masts offered by these companies are crap.

Slight tangent here, but have you tried the https://projectcedrus.com/ masts cnski?
These masts are noticeably draggy

Not to be rude but is that statement coming from personal experience?

Thank you for your discussion and interest, Kyle

Yes, my statement is from personal experience.  A friend of mine asked me to try his setup because he suspected increased drag and so I had an opportunity to do some extensive back to back testing and there was a noticeable reduction in acceleration and glide.  The reduction in glide was not subtle.  Kiters who ride powered all the time may not notice it as much, but for my style of foiling, it was very obvious.

I believe forums like this are great for sharing knowledge and work best when people with specific information report it honestly.  I have learned a lot here and hope I am doing my share to keep this forum the excellent platform it is.


Phils

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Re: Axis Foils
« Reply #467 on: October 17, 2020, 01:59:02 AM »
Pretty much all the carbon masts offered by these companies are crap.

Slight tangent here, but have you tried the https://projectcedrus.com/ masts cnski?
These masts are noticeably draggy

....

Secondly, not one of those customers has complained of "noticeably more drag."



Those may not be the exact words but below is a quote from you:

"His feedback, to be entirely honest, was mixed. He admitted that he immediately noticed and loved the increased stiffness. His foil felt more responsive, and carved very well. But, he said the setup felt slow, which again to be entirely honest, wasn’t a surprise. Project Cedrus is about 19mm thick, which is probably 4-5mm thicker than the bottom of the Moses mast, which means 30% more drag."

I have spoken to the rider whose feedback you report above.  He is an industry pro whose opinions I trust and I own several of his boards.

I am not going to take the time to find the quote now but I remember you writing somewhere in reference to the increased drag in your masts something to the effect that a slower foil may not always be a bad thing. 

In my opinion, increased drag in a mast is a complete deal breaker.

BayAreaKite

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Re: Axis Foils
« Reply #468 on: October 17, 2020, 07:10:59 AM »
Admin, thanks for the comments. You are reiterating one of my key points, which is that the wing contributes to a much larger portion of total drag than the mast. With wings you have wetted surface/skin drag, and lift-induced drag. Many of the wings now have a longer span than the length of the mast, which is insane considering where we were only 2 years ago! So yes, shaving 1-2mm from the thickness of a foil wing can have a bigger impact than shaving the same thickness off the mast because the wings are responsible for a larger portion of the total drag. And if we're going to talk about take-offs, you have to consider the drag of the board, which is 100x more draggy than the mast so I'm just going to forget about comments regarding Cedrus and takeoff;)

I could certainly do a tapered and even thinner version of Project Cedrus. This is the natural evolution of optimized product design; remember this is only gen 1. One of the things I have loved most about engineering at companies like Boeing and Apple is working with other engineers to converge on a solution that satisfies everyone involved in the design. In the case of Cedrus, I am trying to balance manufacturing constraints (remember, this is the only hollow carbon mast!), compatibility with different wings(!!), environmental concerns (using re-purposed aerospace prepreg), cost, structures, hydrodynamics, and weight. I was also a bit conservative with my first version, because I would rather someone pass on the product because of drag concerns than see pictures on forums of broken masts. Thankfully I was conservative, because the size of wings and boards people are riding these days could not have been predicted 3 years ago when I started this. So if/when there is another iteration, I could certainly taper or reduce thickness. But would reducing drag 10-20% result in a sales increase enough to cover the cost of new molds and tooling? I don't know... not a gamble i can afford to take at this time.

Phils, thank you for posting the quote from my blog. I'm glad people read the contents of my site, it has taken a lot of time and effort. As mentioned previously, yes this rider was riding faster Moses wings (633) AND using an older style adapter which made the increased drag more noticeable. One of the many things I have learned on this project over the past couple years is that the adapter design actually has significant impacts on performance and drag. If you look at my Lift and Axis adapters for example, you don't see them... they are recessed in the fuselage. But with Moses, there is a lot going on to get the surfaces to mate in an area that is already experiencing turbulent flow. I have refined all of my adapters over the years to reduce drag... in fact going a little too far with Moses so read that blog if you want a lesson in structures/FEA.

The quote regarding thinner masts causing higher lift induced drag is on my FAQ: https://projectcedrus.com/faq/ Basically, if the mast is too wing-like, you can generate lift (drag) which may be undesirable. This statement is from the gentlemen who designed the foils for Team Oracle (America's Cup) and SailGP. I worked closely with him to optimize my mast section. I am not an aero/CFD engineer, I am a structures guy. I cannot explain the voodoo science that's going on in the waters around a foil, in fact even the experts still don't entirely know. But his point was simply that thinner isn't always better depending on the objective.

Thanks again for all the discussion. I did not intend to high jack a post on Axis foils, but appreciate the topic came up. Project Cedrus is not perfect, and it never will be. That's the fun part of design and engineering:) I am however thankful that enough people think it's the right product for them to justify its existence and my investment of time and capital. It's been an unbelievable learning experience, and I am honored when someone forks over their hard earned money and nothing feels better than that first ride report which is usually very positive. Thanks again for the discussion and at risk of upsetting mods & admins I will refrain from any more sales pitch, if you can even call it that:)

Admin

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Re: Axis Foils
« Reply #469 on: October 17, 2020, 08:03:02 AM »
So if/when there is another iteration, I could certainly taper or reduce thickness. But would reducing drag 10-20% result in a sales increase enough to cover the cost of new molds and tooling? I don't know... not a gamble i can afford to take at this time.

I think that it would definitely be worth the effort.  You have already come most of the way.  I considered buying a couple of your masts but I didn't want to add the drag back in that we had shed from our Axis 19 aluminum masts.  If you could achieve what Axis has in terms of drag reduction and keep your stiffness and weight that would be exceptional. 

This is a natural for crowdfunding.  I suspect that you would get a significant response.  You would certainly know if you were fully funded before you spent any money and you wouldn't need to go out of pocket at all.  At this point you could move to a single base (industry standard track) and do away with the adaptors there.  That could clean up and simplify that area a lot.  3-4 lengths would likely cover it.

Yes, I am pushing you to blow it up :).

PS:  A question.  Could you taper to, say, 75 cm and then flow into a straight section that you could then trim to achieve various sizes?  You are the expert in strength but if that would work it might allow you to make only one or two molds.


« Last Edit: October 17, 2020, 08:16:15 AM by Admin »

Fishman

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Re: Axis Foils
« Reply #470 on: October 17, 2020, 09:25:26 AM »
Kyle, Since you worked at Boeing you might be familiar with a material they used for cabin floor panels. It was 25 years ago since I've handled one but they were aluminum honey comb core, with what I think was fiberglass on ether side. They were very stiff and lightweight. I know it was expensive but I have wondered if the core of mast could use that material to achieve a ultra lightweight and stiff mast. Maybe worth looking at, or whatever they are using for floor panels nowadays, who knows.

It might have been McDonald Douglas aircraft now that I'm thinking about it
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PonoBill

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Re: Axis Foils
« Reply #471 on: October 18, 2020, 07:31:23 AM »
Every airliner uses honeycomb in the floors and have done so for decades. When women's fashion included stilletto heels some of the chunkier wearers were punching holes in the honeycomb. I think that was roughly 40 years ago. Back in the good old days when Boeing surplus was my primary reason for driving to seattle, I could get the aluminum clad sheets affordably, but the stuff is eye-wateringly expensive as new sheets. Generally the core material is aluminum and the sheets can be anything. I have sheets that are aluminum, steel and Kevlar clad. My steel clad stuff came from Intel, when they disassembled a clean room. It's routinely used for wall panels where dust is a problem. I use it to build shelves and tables in my shop. It resists bending but twists fairly easily.

It's great stuff, but not suitable for foil masts. It's a flat sheet--you can't shape it's thickness. I suppose you could press it to the point that the honeycomb collapsed but that would destroy the structural rigidity. And I've never seen it in thicknesses greater than 1/2". It can't be welded by any process other than spot welding--the honeycomb is glued to the panels.
« Last Edit: October 18, 2020, 07:34:19 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.

Thatspec

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Re: Axis Foils
« Reply #472 on: October 19, 2020, 12:10:55 AM »
Ooooo ;D
Steamroller mentioned this in another thread, this thing looks like the new rear wing of my dreams.
Never got to try it but the long flat shape of the 460 kept me from experimenting. Of course the price keeps creeping up ::)

https://axisfoils.com/collections/wing-foil-wings/products/s-series-carbon-rear-wing-420mm

SanoSlatchSup

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Re: Axis Foils
« Reply #473 on: October 19, 2020, 08:21:26 AM »
Ooooo ;D
Steamroller mentioned this in another thread, this thing looks like the new rear wing of my dreams.
Never got to try it but the long flat shape of the 460 kept me from experimenting. Of course the price keeps creeping up ::)

https://axisfoils.com/collections/wing-foil-wings/products/s-series-carbon-rear-wing-420mm
The 460 is a great stab for speed and pumping...and turns surprisingly well in the surf too boot, but just not as well as the 390 and why the 390 is my "go to" stab since I'm more about "surfing" the foil than I am trying to pump it back out.

Can't wait to get me hands on the new 420, because I think it'll be the sweet spot between the 390's turn-ability, and then 460's speed and pump-ability.
Me: 6'1"/185...5'7" Kings Foil Board...6'0" Kings Foil Board...9'6" Bob Pearson "Laird Noserider"...9'6" Costa Azul Wide Body...14' Lahui Kai "Manta"...8'0" WaveStorm for when proning urges still hit, and 7'3" Chuck Glynn foil board backup.

Thatspec

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Re: Axis Foils
« Reply #474 on: October 20, 2020, 12:06:08 AM »
I also used the 390 all summer and loved it. Never felt like I was missing out on glide but when I look at the specs, I probably was. The 390 has about 3x the volume of the 460 and appears to be their highest volume tail (even more than the 500). Sure there are other factors but that's a big one.

I just received the two Gong Veloce tails which have fairly long spans (43 and 47cm), but really low volumes (.09 and .12L). Wonder if I'll really need the larger but maybe it'll be great with the 2XL front wing at 107cm. Already thinking about bolting the Axis 420 to the tail of Gong mast. Unfortunately they use 25mm spacing and everyone else seems to use 30 which means a permanent mod to a $240 stab :( I wonder if one bolt is enough to hold it on through a couple of reaches for a pre mod experiment?

Admin

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Re: Axis Foils
« Reply #475 on: October 20, 2020, 01:13:55 AM »
The 390 has about 3x the volume of the 460 and appears to be their highest volume tail (even more than the 500).

Do they have that info online somewhere (volume, etc)?  I would love to see that.  It would seem odd that it was higher volume.  It feels the same thickness as the other tails and it has less chord than the 400 and above.  I have been really happy with the 390's but it would be cool to see what this one does :)

Thatspec

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Re: Axis Foils
« Reply #476 on: October 20, 2020, 07:54:16 AM »

Do they have that info online somewhere (volume, etc)?  I would love to see that. 

Someone updated the Axis info in the Google doc. It seems to be the most complete of any brand (no 420 tail yet...) though many numbers of other brands don't really rough out in my head. I've not really had a good look at a 370 for instance and this is saying the 390 has about twice the volume.

Ya know, it would make sense that the .24255 liters of the 390 is actually .14255. Then it would fit right in line with the others perfectly :)

https://docs.google.com/spreadsheets/d/17xbTGEWSVeRhnYb_4vz_Gmby8UnrDys7Q1iB-6rC6F4/edit#gid=0

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Re: Axis Foils
« Reply #477 on: October 20, 2020, 09:06:41 AM »
Thanks! Yeah, that looks like a simple typo (there are a lot of errors on that doc).  This 420 is going to be super low volume.  That sounds really nice.  We will have to try one!
« Last Edit: October 20, 2020, 09:11:23 AM by Admin »

Hdip

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Re: Axis Foils
« Reply #478 on: October 20, 2020, 10:35:58 AM »
Has anyone seen one in person to compare the 460 to the 420? According the the lift designer on the progression project. Winglets are exactly the same as having an extra inch of flat wing. Both the 460 and the 420 have the same chord. Is it just flipped tips? That would give you a bit better control over yaw. I wonder if the 420 is thinner though.

Admin

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Re: Axis Foils
« Reply #479 on: October 21, 2020, 02:20:47 AM »
I saw this comment from Adrian Roper from Axis over on Facebook (in a funny thread which turned into a debate about the most important single factor for foil design):

Adrian: back to the original question my main ride recently (prototype wing) has been a wing with an area of 1200cm2 but span of 980mm, a mean average chord of 124mm, aspect ratio of 7.89. Great fun very fast, carvy and fun to ride. Not 1000cm2 but close and I am 89kg.

Sounds like there are some new super high aspect foils in the works.  4.9 inches of average chord. 
« Last Edit: October 21, 2020, 02:23:14 AM by Admin »

 


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