Sailplane data

JJ21

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Feb 8, 2011, 4:44:45 AM2/8/11

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Hi all,

I'm currently doing a project on gliders designed within the last ten
years and one of the crucial aspects is knowing the mean camber profile
for various lift coefficient calculations. I was wondering whether
a) Any modern gliders are using NACA type airfoils?
b) Whether anyone knows what the parabolic equation of the ASG-29
profile?

Any other suggestions would be greatly appreciated!

Thanks

--
JJ21

Andreas Maurer

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Feb 8, 2011, 9:25:08 AM2/8/11

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On Tue, 8 Feb 2011 09:44:45 +0000, JJ21
<JJ21.7...@aviationbanter.com> wrote:

>a) Any modern gliders are using NACA type airfoils?

Nope... I'd estimate since at least 50 years...

>b) Whether anyone knows what the parabolic equation of the ASG-29
>profile?

If you men the parabolic equation that defines the camber and
thickness distribution of NACA airfoil:

Laminar airfoils that are used on gliders don't use parabolic
equations - their shape is defined by calculating the shape based upon
pressure distribution.

Regards
Andreas

Grider Pirate

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Feb 8, 2011, 9:44:50 AM2/8/11

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http://www.sailplanedirectory.com lists the airfoil used for SOME
gliders.

Some of those airfoil sections can be found here:
http://www.ae.illinois.edu/m-selig/ads/coord_database.html

jsbrake

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Feb 8, 2011, 11:03:09 AM2/8/11

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By "parabolic equation", perhaps the OP means the polar calculation
points? Parabolic is synonymous with quadratic, which is what we use
to approximate our polars for the computers.

uncl...@ix.netcom.com

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Feb 8, 2011, 11:07:48 AM2/8/11

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Airfoil is DU89-134/14. Coordinates are not available to my knowledge.
I'd like to be proven wrong on that.
UH

JJ21

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Feb 9, 2011, 2:34:20 PM2/9/11

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'jsbrake[_2_ Wrote:
> ;762016']By "parabolic equation", perhaps the OP means the polar

> calculation
> points? Parabolic is synonymous with quadratic, which is what we use
> to approximate our polars for the computers.

Pretty much looking for a quadratic which can be used to calculate the
lift coefficient theoretically using Fourier coefficients.
I can't really think of any other way of calculating the lift
coefficient of an airfoil theoretically.

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JJ21

Francisco De Almeida

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Feb 9, 2011, 7:28:23 PM2/9/11

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>I can't really think of any other way of calculating the lift
>coefficient of an airfoil theoretically.

A lot of good people have found more straightforward ways to compute the
lift coefficient, which is in fact very easy to calculate. The maximum
lift coefficient, the drag coefficient, the pitching moment coefficient
are the hard ones.

Perhaps you could consult a standard textbook on glider aerodynamics, e.g.
Prof. Fred Thomas "Handbook of Sailplane Design".

Doug Greenwell

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Feb 10, 2011, 5:47:59 AM2/10/11

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If you have the aerofoil profile, then Xfoil (freeware from a very
respected aerodynamicist) will give you a reasonable 1st guess at all of
these for 2D flow. XFLR5 extends Xfoil to 3D wings (originally intended
for RC gliders, but should probably* be OK for full-scale sailplanes).

Using Fourier coefficients to calculate 2D (or 3D wing) characteristics,
is a real throw-back to the 50's - useful in a textbook derivation to
give an analytical solution, but no-one does it any more.

Doug

*usual caveats apply - these are not guaranteed to give the right answer,
so use with caution!