Forums > Stand Up Paddle Foiling

Foil aspects explained ?

Reply
Created by Krist Two weeks ago, 1 Jun 2019
Krist
QLD, 260 posts
1 Jun 2019 9:38PM
Thumbs Up

gday does anyone have the time to give me a simpleton version for foil aspects ie high aspect foil cheers

Clamsmasha
WA, 46 posts
1 Jun 2019 10:13PM
Thumbs Up

Select to expand quote
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, 4605 posts
4 Jun 2019 7:59AM
Thumbs Up

Both 900mm wide.





Piros
QLD, 5442 posts
4 Jun 2019 10:32AM
Thumbs Up

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
201 posts
4 Jun 2019 11:08AM
Thumbs Up

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

Scotty Mac
SA, 1858 posts
4 Jun 2019 2:26PM
Thumbs Up

Bloody hell Hilly goes high tech!

Piros
QLD, 5442 posts
4 Jun 2019 5:26PM
Thumbs Up

Select to expand quote
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, 1156 posts
4 Jun 2019 6:33PM
Thumbs Up

Select to expand quote
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, 4605 posts
4 Jun 2019 5:30PM
Thumbs Up

Select to expand quote
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, 1858 posts
4 Jun 2019 7:38PM
Thumbs Up

Geeze hilly one minute you got me impressed bro.... nec minuite i am blown away.....

Scotty Mac
SA, 1858 posts
4 Jun 2019 7:40PM
Thumbs Up

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, 4605 posts
4 Jun 2019 8:06PM
Thumbs Up

Select to expand quote
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, 1503 posts
5 Jun 2019 6:13AM
Thumbs Up

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
33 posts
5 Jun 2019 5:05AM
Thumbs Up

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

hilly
WA, 4605 posts
5 Jun 2019 8:20AM
Thumbs Up

Select to expand quote
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, 4605 posts
5 Jun 2019 8:22AM
Thumbs Up

Select to expand quote
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.



Subscribe
Reply

Forums > Stand Up Paddle Foiling


"Foil aspects explained ?" started by Krist