Forums > Stand Up Paddle Foiling

Foil aspects explained ?

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Created by Krist 2 months ago, 1 Jun 2019
Krist
QLD, 272 posts
1 Jun 2019 9:38PM
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gday does anyone have the time to give me a simpleton version for foil aspects ie high aspect foil cheers

Clamsmasha
WA, 73 posts
1 Jun 2019 10:13PM
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Krist said..
gday does anyone have the time to give me a simpleton version for foil aspects ie high aspect foil cheers


In a very small nutshell, a high aspect ratio foil is a long wing with a short chord (length from leading to trailing edge).

Low aspect ratio is the opposite.

Aspect ratio changes some important hydrodynamic traits.

Higher aspect ratio foils produce lower induced drag (drag resultant of lift generation).

The longer the wing section the greater the form drag (more or less the the force acting against the length of the foil as it pushes through the water). If the Low and High aspect foils being compared have the same span, there will not be an increase in form drag, all things being equal.

Higher aspect ratios cause slightly higher coefficient of drag but it is very small. They also exhibit a lower maximum coefficient of lift.

Thinner wing sections pay less of a penalty in the form of skin friction drag. These new foils seem to be substantially thinner.

You can expect these new wings to be very efficient with higher top speeds. Equivalent spans probably won't lift at such low speeds, but will have better glide ratio....be better for pumping. I'm guessing also that the flatter thinner ones won't lose their **** quite as badly due to partial breaches.

hilly
WA, 4745 posts
4 Jun 2019 7:59AM
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Both 900mm wide.





Piros
QLD, 5487 posts
4 Jun 2019 10:32AM
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Great pic Hilly , low aspect on left with more low speed lift but slower top end speed . The higher aspect on the right might not have same initial lift but will carry more speed without blow out or breaching , they are also more efficient to pump. So overall once you have the speed it's easier to maintain it with a higher aspect wing.

exiled
238 posts
4 Jun 2019 11:08AM
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This there a threshold to meet for a foil to be considered 'High aspect ratio'?

Scotty Mac
SA, 1884 posts
4 Jun 2019 2:26PM
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Bloody hell Hilly goes high tech!

Piros
QLD, 5487 posts
4 Jun 2019 5:26PM
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exiled said..
This there a threshold to meet for a foil to be considered 'High aspect ratio'?


A lot less junk in the trunk . Thinner leading edge , narrower cord ( front to back) flatter curve , finer tips plus the angle of attack is reduced. It's getting all that right is the hard part .

warwickl
NSW, 1195 posts
4 Jun 2019 6:33PM
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Piros said..

exiled said..
This there a threshold to meet for a foil to be considered 'High aspect ratio'?



A lot less junk in the trunk . Thinner leading edge , narrower cord ( front to back) flatter curve , finer tips plus the angle of attack is reduced. It's getting all that right is the hard part .


I have a Moses 683 which maybe a good example compared with the 633 wing.
I have a Naish medium and purchased the Moses 683 and immediately noticed the refinement Piros is talking about.

hilly
WA, 4745 posts
4 Jun 2019 5:30PM
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Scotty Mac said..
Bloody hell Hilly goes high tech!


Got one of these on the way Cannot wait, no more corrosion or fizz as it is called in nu zeeland

www.armstrongfoils.com/cf1600-set-up-options/

Scotty Mac
SA, 1884 posts
4 Jun 2019 7:38PM
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Geeze hilly one minute you got me impressed bro.... nec minuite i am blown away.....

Scotty Mac
SA, 1884 posts
4 Jun 2019 7:40PM
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No fizz on the go foil hilly but I do like the feel of those axis 900 wings! So good for pumping and damm fast!

hilly
WA, 4745 posts
4 Jun 2019 8:06PM
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Scotty Mac said..
No fizz on the go foil hilly but I do like the feel of those axis 900 wings! So good for pumping and damm fast!


Mine is the 920 on the left. Bit slow and hard work in a bit of size.

toppleover
QLD, 1523 posts
5 Jun 2019 6:13AM
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Looking forward you your review Hilly.

Now back to the OP, I have read lots of good things on this thread about high aspect wings but surely there must be some trade-offs / compromises.
I have heard they don't turn as good as low aspect ?

sweats
54 posts
5 Jun 2019 5:05AM
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Hi Hilly. Is it just the picture or is the new high aspect Axis 900 wing mounted on a shortened fuse?

hilly
WA, 4745 posts
5 Jun 2019 8:20AM
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sweats said..
Hi Hilly. Is it just the picture or is the new high aspect Axis 900 wing mounted on a shortened fuse?


Yes it is the new shorter fuse. It is not mine and I have not surfed the 900 wing or fuse. Owner really likes the combo @ 80kg.

hilly
WA, 4745 posts
5 Jun 2019 8:22AM
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toppleover said..
I have heard they don't turn as good as low aspect ?


The owner of the 900 was turning really well, no issues there. He says you have to be more active pumping and turning to keep gliding on smaller days. The gain seems to be on faster waves.

emmafoils
72 posts
11 Jul 2019 5:39PM
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Piros said..
Great pic Hilly , low aspect on left with more low speed lift but slower top end speed . The higher aspect on the right might not have same initial lift but will carry more speed without blow out or breaching , they are also more efficient to pump. So overall once you have the speed it's easier to maintain it with a higher aspect wing.


Not sure I agree. My understanding is that if you have 2 wings with same surface area and similar profiles, the higher AR wing will have MORE lift. It will also glide better and have higher top end. The downside is the higher AR wing will turn slower and have a more violent stall.

windara
QLD, 241 posts
12 Jul 2019 6:25AM
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hilly said..

sweats said..
Hi Hilly. Is it just the picture or is the new high aspect Axis 900 wing mounted on a shortened fuse?



Yes it is the new shorter fuse. It is not mine and I have not surfed the 900 wing or fuse. Owner really likes the combo @ 80kg.


Is it the short or ultra short fuse? And what is a good rear wing to use with the 900 S series front wing? Cheers

toppleover
QLD, 1523 posts
12 Jul 2019 6:51AM
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windara said..

hilly said..


sweats said..
Hi Hilly. Is it just the picture or is the new high aspect Axis 900 wing mounted on a shortened fuse?




Yes it is the new shorter fuse. It is not mine and I have not surfed the 900 wing or fuse. Owner really likes the combo @ 80kg.



Is it the short or ultra short fuse? And what is a good rear wing to use with the 900 S series front wing? Cheers


For the 900S/Ultra-short, I've been informed to get the 440 rear (if u want max pump) or 400 for carving.

JB
NSW, 2000 posts
Site Sponsor
12 Jul 2019 6:58AM
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There is actually quite a bit to AR and the Characteristics they hold. Some good insight above. Here's my findings.

During testing of the NEW Naish wings about to the hit the market any second, I had the chance to compare 3 x equal PSA (projected Surface Area) wings all with considerably different AR (Aspect Ratio). My findings were very interesting.

AR 4.1 - Super stable and a very easy lift. GPS bottom end speed for easy foiling approx. 12km/h +/-. Max speeds 25-27km/h +/-

AR 5.1 - Still quite stable, a little more lively. GPS bottom end not massively changed - approx. 12km/h. Max speeds 27-29km/h +/-.

AR 6.1 - Crazy lively. Very reactive to the point I got served quite a few times trying to push it. GPS bottom ends was amazing easily 11km/h or less. Top Speeds in the 31-32km/h.

I found that the higher AR wings had either the same or increased bottom end as well as adding increased top end. However the HA wings are increasingly harder to use. Significant enough that we went with the AR 4.1 for the production model. I always point out to riders when their feet are not centre, and this is why. I found even on the tiny offset that I might have (I am generally very centre), it would result in losing control as soon as things load up. The HA wings are so sensitive to any pressure that they react immediately and powerfully. Whilst this is great for the advanced rider wishing to push the limits, it is a learning curve and way more exact science.

Having the choice now is great, and I often go between wings to learn more. Basically my 1800 HA (different wing then above) is more powerful, faster and better bottom end than my 2000. But I have not had my ass kicked like this in ages.

There is so much that goes into wings, and they're all very different in so many ways. But to be really blunt with the concept,

Low Aspect = stable, easy to control, smooth lineal accelleration.

High Aspect = Fast, super responsive, aggressive accelleration.

I do believe HA wings will be a big part of foiling as our skills continue to improve. But there is a great simplicity in easy and comfortable also.

Ride safe,

JB

emmafoils
72 posts
12 Jul 2019 6:08AM
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JB said..
There is actually quite a bit to AR and the Characteristics they hold. Some good insight above. Here's my findings.

During testing of the NEW Naish wings about to the hit the market any second, I had the chance to compare 3 x equal PSA (projected Surface Area) wings all with considerably different AR (Aspect Ratio). My findings were very interesting.

AR 4.1 - Super stable and a very easy lift. GPS bottom end speed for easy foiling approx. 12km/h +/-. Max speeds 25-27km/h +/-

AR 5.1 - Still quite stable, a little more lively. GPS bottom end not massively changed - approx. 12km/h. Max speeds 27-29km/h +/-.

AR 6.1 - Crazy lively. Very reactive to the point I got served quite a few times trying to push it. GPS bottom ends was amazing easily 11km/h or less. Top Speeds in the 31-32km/h.

I found that the higher AR wings had either the same or increased bottom end as well as adding increased top end. However the HA wings are increasingly harder to use. Significant enough that we went with the AR 4.1 for the production model. I always point out to riders when their feet are not centre, and this is why. I found even on the tiny offset that I might have (I am generally very centre), it would result in losing control as soon as things load up. The HA wings are so sensitive to any pressure that they react immediately and powerfully. Whilst this is great for the advanced rider wishing to push the limits, it is a learning curve and way more exact science.

Having the choice now is great, and I often go between wings to learn more. Basically my 1800 HA (different wing then above) is more powerful, faster and better bottom end than my 2000. But I have not had my ass kicked like this in ages.

There is so much that goes into wings, and they're all very different in so many ways. But to be really blunt with the concept,

Low Aspect = stable, easy to control, smooth lineal accelleration.

High Aspect = Fast, super responsive, aggressive accelleration.

I do believe HA wings will be a big part of foiling as our skills continue to improve. But there is a great simplicity in easy and comfortable also.

Ride safe,

JB


Very helpful. When you say higher AR is more reactive, can you be more specific? Are we talking speed changes or reactivity in an axis such as pitch or roll?

Approx what surface area where the 3 wings you tested?

Also, can you comment on carving ability. My theoretical understanding is higher AR should equal less tight carves.

hilly
WA, 4745 posts
12 Jul 2019 1:58PM
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windara said..

hilly said..


sweats said..
Hi Hilly. Is it just the picture or is the new high aspect Axis 900 wing mounted on a shortened fuse?




Yes it is the new shorter fuse. It is not mine and I have not surfed the 900 wing or fuse. Owner really likes the combo @ 80kg.



Is it the short or ultra short fuse? And what is a good rear wing to use with the 900 S series front wing? Cheers


It is the short. 440 is my pick.

colas
3322 posts
12 Jul 2019 2:15PM
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emmafoils said..
My theoretical understanding is higher AR should equal less tight carves.


Yes, especially on wide wings: in turns, the tips of the wing will travel at very different speeds: the outer tip will go faster, and the inner tip slower. In planes, this create the dangerous "wing drop" spin.
www.experimentalaircraft.info/flight-planning/aircraft-stall-effect.php

Higher aspect ratio wings stall easier (at higher speeds), so an high AR foil will tend to stall the inner wing in turns if you do not keep a fast enough speed. The design of the wings can also help prevent it, or at least make the stalling less disruptive for the pilot.

exiled
238 posts
12 Jul 2019 5:24PM
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Its going to be really interesting to hear the ride reports once these high aspect wings hit the general public. You can't watch Derek Hama do his thing and say they don't work, but I have to wonder how many mortals will be able to make the jump. I can't help but wonder if this time next year we'll be hearing about the next generation of mid-aspect foils...

Clamsmasha
WA, 73 posts
12 Jul 2019 7:20PM
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exiled said..
Its going to be really interesting to hear the ride reports once these high aspect wings hit the general public. You can't watch Derek Hama do his thing and say they don't work, but I have to wonder how many mortals will be able to make the jump. I can't help but wonder if this time next year we'll be hearing about the next generation of mid-aspect foils...



I've been watching 3 guys around here riding the 900 and they are throwing some nice hard turns . They seem to be doing everything considerably faster than the LA wings too. They are good foilers, and they swear by the HA wings for downwinding and pumping, I think they are loving them in the surf too now.

you are probably right about the mid aspect thing..there are a lot of things that can be tweaked and I always though thinner less lifty versions of my Gofoil wings would be a nice compromise rather than going full glider...having said that I have my name on a GL210 and I know I'm going to like wherever it fits.

strap in and hold onto you wallet, I guess we're going to see it all as the "new 20xx range" comes out every year.

windara
QLD, 241 posts
13 Jul 2019 8:22AM
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toppleover said..

windara said..


hilly said..



sweats said..
Hi Hilly. Is it just the picture or is the new high aspect Axis 900 wing mounted on a shortened fuse?





Yes it is the new shorter fuse. It is not mine and I have not surfed the 900 wing or fuse. Owner really likes the combo @ 80kg.




Is it the short or ultra short fuse? And what is a good rear wing to use with the 900 S series front wing? Cheers



For the 900S/Ultra-short, I've been informed to get the 440 rear (if u want max pump) or 400 for carving.


Cheers for that !

windara
QLD, 241 posts
13 Jul 2019 8:23AM
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Select to expand quote
hilly said..

windara said..


hilly said..



sweats said..
Hi Hilly. Is it just the picture or is the new high aspect Axis 900 wing mounted on a shortened fuse?





Yes it is the new shorter fuse. It is not mine and I have not surfed the 900 wing or fuse. Owner really likes the combo @ 80kg.




Is it the short or ultra short fuse? And what is a good rear wing to use with the 900 S series front wing? Cheers



It is the short. 440 is my pick.


Thanks hilly

JB
NSW, 2000 posts
Site Sponsor
14 Jul 2019 6:54AM
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Select to expand quote
emmafoils said..

JB said..
There is actually quite a bit to AR and the Characteristics they hold. Some good insight above. Here's my findings.

During testing of the NEW Naish wings about to the hit the market any second, I had the chance to compare 3 x equal PSA (projected Surface Area) wings all with considerably different AR (Aspect Ratio). My findings were very interesting.

AR 4.1 - Super stable and a very easy lift. GPS bottom end speed for easy foiling approx. 12km/h +/-. Max speeds 25-27km/h +/-

AR 5.1 - Still quite stable, a little more lively. GPS bottom end not massively changed - approx. 12km/h. Max speeds 27-29km/h +/-.

AR 6.1 - Crazy lively. Very reactive to the point I got served quite a few times trying to push it. GPS bottom ends was amazing easily 11km/h or less. Top Speeds in the 31-32km/h.

I found that the higher AR wings had either the same or increased bottom end as well as adding increased top end. However the HA wings are increasingly harder to use. Significant enough that we went with the AR 4.1 for the production model. I always point out to riders when their feet are not centre, and this is why. I found even on the tiny offset that I might have (I am generally very centre), it would result in losing control as soon as things load up. The HA wings are so sensitive to any pressure that they react immediately and powerfully. Whilst this is great for the advanced rider wishing to push the limits, it is a learning curve and way more exact science.

Having the choice now is great, and I often go between wings to learn more. Basically my 1800 HA (different wing then above) is more powerful, faster and better bottom end than my 2000. But I have not had my ass kicked like this in ages.

There is so much that goes into wings, and they're all very different in so many ways. But to be really blunt with the concept,

Low Aspect = stable, easy to control, smooth lineal accelleration.

High Aspect = Fast, super responsive, aggressive accelleration.

I do believe HA wings will be a big part of foiling as our skills continue to improve. But there is a great simplicity in easy and comfortable also.

Ride safe,

JB



Very helpful. When you say higher AR is more reactive, can you be more specific? Are we talking speed changes or reactivity in an axis such as pitch or roll?

Approx what surface area where the 3 wings you tested?

Also, can you comment on carving ability. My theoretical understanding is higher AR should equal less tight carves.


More reactive in every way! Any input into a higher aspect wing will result in a reaction that is more aggressive and faster than a lower aspect relative wing. Speed - Acceleration is much faster, higher top speeds and speed of pitch and roll change is much much faster and requires far less input to achieve a more drastic adjustment.

I was testing 2450's. And have since been riding Std Aspect 1650 & 2000 vs a HA 1800. HA 1800 is faster and looser than the 1650 and delivers more lift than the 2000, but much harder to ride.

Carving ability will come down to the rider. Technically a better rider will be able to carve a HA wing tighter and faster than a LA. But it will have significantly more load and lift being generated it would not take much to get your ass served if you made an error (like moving your pinky toe when you shouldn't have).

HA wings will not be for everyone, maybe not even me. But they are impressive for that ultimate performance.

I would suggest 100% mastering a LA wing before venturing into HA.

Ride safe,

JB

toppleover
QLD, 1523 posts
30 Jul 2019 11:00AM
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Tow-ins/High Aspect wings/Shimming, it's all discussed here...
Listen to Foiling Series Ep. 4 - James Casey Round 2 by The Progression Project on #SoundCloud soundcloud.com/progressionproject/foiling-series-ep-5-james-casey-round-2

Camarillo
186 posts
30 Jul 2019 3:37PM
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The Aspect Ratio of a wing is defined to be the square of the span divided by the wing area and is given the symbol AR.

But should the projected area be used for that?

For instance for the Axis S102:

With projected surface: 102^2/2013= 5,168

In the foil database: docs.google.com/spreadsheets/d/17xbTGEWSVeRhnYb_4vz_Gmby8UnrDys7Q1iB-6rC6F4/edit?usp=sharing

Some of the entries for AR are calculated with the right formula, with projected or 'normal' surface and some of then are just the number.
But some of these numbers are not right imo.

For instance Axis:












Clamsmasha
WA, 73 posts
30 Jul 2019 4:11PM
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Not projected for aspect ratio, always actual area.



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"Foil aspects explained ?" started by Krist