Author Topic: Actual vs Projected area  (Read 444 times)

Admin

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Actual vs Projected area
« on: July 12, 2020, 04:11:50 AM »
Axis is giving two measurements for area, Actual and Projected.  My understanding is that Actual measures 3D surface area and Projected measures the area of the 2D outline.  What are other brands measuring?

Lazz

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Re: Actual vs Projected area
« Reply #1 on: July 12, 2020, 06:18:29 AM »
They all measure the same way. With "Actual and Projected in cm2"  the description  is clear and shouldnt give  room for misinterpretation.
The projected 2D surface gives a indication for the application.The 3D surface (Volumen) gives the indication of the profile characteristic. High value= thicker, slower, Low value= thinner,faster.
« Last Edit: July 12, 2020, 06:26:26 AM by Lazz »

Admin

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Re: Actual vs Projected area
« Reply #2 on: July 12, 2020, 07:02:36 AM »
Thanks Lazz.  I am only finding a single measurement from brand websites (Armstrong, Moses, Lift, etc) and they are not indicating if that is Actual or Projected Area (as far as I can tell).
« Last Edit: July 12, 2020, 07:51:11 AM by Admin »

Phils

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Re: Actual vs Projected area
« Reply #3 on: July 12, 2020, 07:53:37 AM »
Itís a really good question as most publish only one number and donít specify what they are measuring. I emailed Armstrong to ask what they use.   I read somewhere that Naish uses projected.  Goes to show you that these numbers are really most useful for comparing within a brandsí products.

Lazz

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Re: Actual vs Projected area
« Reply #4 on: July 12, 2020, 08:06:19 AM »
On closer looking in to the Axis frontwing data, there is no way the "Actuel" named 3D surface  value include the whole foil surface ( volumen). It seems the measurement means only the surface of the suction side (upper curvy side) of the foil. The new HA Axis wings 1150 and 910 have a actuel surface approx.~ 4% more as the projected.
Not sure this is also for the Moses 1100 relevant which is more a medium HA.

Disclaimer: provided the Axis information is correct. ;)
« Last Edit: July 12, 2020, 08:09:51 AM by Lazz »

Admin

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Re: Actual vs Projected area
« Reply #5 on: July 12, 2020, 08:14:13 AM »
Hi Lazz,

Yes, Axis lists Actual area, Projected area and Volume for each foil (3 measurements).  My question is really more about the other brands.  I am interested in knowing this for wings like the Axis 920 and Armstong 1850 which list very similar measurements but I am unsure what figure Armstrong is giving.  Phils had mentioned this in a post yesterday and it set me to thinking...
 
« Last Edit: July 12, 2020, 08:59:41 AM by Admin »

PonoBill

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Re: Actual vs Projected area
« Reply #6 on: July 12, 2020, 09:27:30 AM »
It's kind of weird that Axis reports actual area since it's not really more predictive of how the wing performs. There really isn't a single value that permits easy comparison of one wing to another.

The area is one element of the lift equation. In water, the only other important variable other than velocity is the foil coefficient, which is more of an empirical value than a calculable one. The calculation in air is more complex because of compressibility.  The actual area vs. projected area captures the foil coefficient to some small degree. It's a simplified way to guess at lift, but it's obviously not really predictive. You could have a wing whose airfoil cross-section is a triangle that would have a high actual area relative to projected but would not make for a good foiling experience. But providing the foil coefficient would not be useful to anyone not prepared to make calculations and measurements and the resultant number gets mostly trumped by velocity in water anyway.

Thank goodness, or rather, physics for that. If velocity wasn't such a big factor I'd never be able to get my fat ass up in the air.
« Last Edit: July 12, 2020, 09:31:31 AM by PonoBill »
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clay

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Re: Actual vs Projected area
« Reply #7 on: July 12, 2020, 12:35:30 PM »
I have found it really helpful to talk to a rep of each company that has ridden a lot of wings.  They have told me how the wing rides and how the lift compares to something I have ridden.  Info I would have been lucky to accurately guess by looking at the numbers.
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