dynamic-polar - AB-AIRFOIL

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The dynamic polar is used  to know the performance of most interest to a glider or aircraft, before building it.
It offers an integral vision performance and allows you to understand what happens during the flight, giving the possibility, by varying the parameters, such as chords, surfaces, wing loadings, aspect ratio and of course the wing airfoil, to achieve
THE BEST POSSIBLE COMBINATION OF ELEMENTS, in order to improve the performance, whatever they may be.

In the late 90's I personally developed this method. Then, in 2002 I updated it with the fundamental help of other people, and recently I resumed it in order to bring it to the present day, coming to the third version.

It may not be perfect, because:

"Everything is not tested in the wind tunnel is somehow estimated"

This sentence deserves a closer look:
At least in modeling applications most of the aerodynamic drag (close to the flight speed) of a glider, derives from the wing.
This simple fact explains why everybody works, and has always worked during the time, in terms of calculation,  on wings and such a little on other aspects.


wing airfoil


Wing area square meter


wingspan of the wings not installed on fuselage.

Wing Aspect Ratio

Wing Aspect Ratio with wings not installed on fuselage


Weight (Kg)


wing load  (gr/dm^2)

NRe Reference

Is declared the NRe of reference of the polar that have been used for the calculation, the color represents the range of NRe on the polar used in consequence of the change of incidence of the veivolo in flight.

The polar choices are based on availability and type (theorical/experimental/ lambda absolute or lambda finished)


Root chord (meter)


Mean chord (meter)


Tip chord (meter)

Airplane Wingspan

Airplane wingspan (wings installed)

Airpl. Aspect Ratio

Airplane Aspect ratio (wings installed)

Min. Speed m/s

detected value of the minimum speed in column V in meters per second refers to the polar NRe reference value with the lowest (first)

corresponds to the stalling speed,
and for all practical purposes with a slight increase at the launch and landing speed.

Limit Speed m/s

Value calculated speed limit referred to NRe polar reference with the highest value available.

Speed approximate limit, in order to minimal Cd, is almost always equal to zero lift,vertical dive keeping.


NRe mean chord wing


angle of incidence wing lambda 5


angle of incidence wing on airplane in flight


coefficent lift


efficency airplane

All the calculation is done primarily to obtain and be able to improve this value.


power factor

It's an index that can be used to understand how much faster you climb in thermals.


wing drag


vertical speed (meter/sec)

V m/s

in flight velocity (meter/sec)

V km/h

in flight velocity (kilometer/hour)


current version:V 3.3

V3.3 has been extended the number of the polars to calculate
speed limit, which remains an approximate value.

Fixed references in the fields Wing aspect ratio, Wings and C.mean,
(the values for the calculation were instead corrected)

Aspect Ratio reference is now for calculating the resulting average
of Aspect Ratio with the wings installed on the fuselage (A.R.airplane) and not (A.R. wing).
This is to standardize the method, and consequently to simplify the comparison
and define clearly for all the A.R. used.
Previous versions used instead of the A.R. Wing.

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