Hangglider aerodynamic polar simulator

Interactive Java application for study of hangglider flight polar.
Changes:
1.0 - first official version
1.1 - added circling characteristics
1.2 - recompiled (runs in MS JavaVM)
1.3 - GUI refined (requires Java from Sun)
1.4 - resolved bug (small numerical instability) (last updated 24.11.2008)

Simulator is based on simple idea of parabolic drag, where aerodynamic drag (X), is comprised of fixed drag (X0) (independently of AoA), and induced drag (Xi). Induced drag is dependent on square of lift and inverse of AR (Aspect Ratio). This model well represents rigid wing, without any separation. This model is less acurate in these situations:

close proximity of stall - i.e. separated flow (cx0 changes), big change in wing twist (AR changes)
maximum speed - i.e. separated flow on bottom sail (cx0 changes)
small glider - i.e. low Reynolds number -> cx0 changes (cannot be assumed fixed)
tight turn (small radius) - i.e. flow cannot be assumed planar (cx0= ?, cxi= ?, stall point ?)

Variables marked by "*" are dynamically computed based on all other variables, PLUS "*"-variables in opposite column. You can input EITHER definition points of polar OR glider parameters. Weight (m), wing area (S), and altitude can be set independently.

SI unit system is used (kg.m.s). "cx0" represents parasitic drag, e.g. drag of harness, downtubes, kingpost etc. "lambda" is effective AR, it is AR of equivalent elliptical untwisted wing with the same surface area, whose induced drag is the same. So you can simulate both different shape of the sail and tension of the sail (twist). Once again: "Value of effective Aspect Ratio IS NOT value of AR which you can find on glider manufacturer website". (Our gliders have only efficiency of elliptical wing with lower AR.)

If you use obsolete Microsoft version of Java (prior-XP Windows), I strongly encourgage you to transit to original Sun Java . You need only Java Runtime Environment (JRE), or Java Virtual Machine (Java VM). It's about 14MB and it's free (Look for Popular downloads at java.sun.com). It gives you ability tu run this program offline, and also run newest 1.4 version.

Download old 1.2 version (for MS Java) (20kB).
Download latest 1.4 version (requires Java 1.3 or higher) (24kB).

Definition points you can also use for detection of sink at taken speed (users of old Braunigers). Also, you can see, that definition points are seen in every graph. However, they don't show point on the graph with taken speed, but show point at the same Angle of attack (the same control bar position) - see Circling characteristics.

Here is some additional info:
How to obtain intermediate points of the polar
Description of the model

Here is some polar data from various sources. All converted to SI units (m/s@km/h):

glider 1st point on polar 2nd point on polar source:
WillsWing Falcon 1.09@30.6 2.69@54.7 WillsWing
WillsWing Eagle 1.04@35.4 2.69@59.5 WillsWing
WillsWing Ultra / Super 1.00@35.4 2.69@64.4 WillsWing
WillsWing Sport 2 0.94@35.4 2.26@64.4 WillsWing
WillsWing U2 / Fusion 0.89@37.0 2.69@70.8 WillsWing
WillsWing Talon 0.89@38.6 2.69@75.6 WillsWing

Peter Gasparovic
(pgproxy1 orangemail sk)

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glider	1st point on polar	2nd point on polar	source:
WillsWing Falcon	1.09@30.6	2.69@54.7	WillsWing
WillsWing Eagle	1.04@35.4	2.69@59.5	WillsWing
WillsWing Ultra / Super	1.00@35.4	2.69@64.4	WillsWing
WillsWing Sport 2	0.94@35.4	2.26@64.4	WillsWing
WillsWing U2 / Fusion	0.89@37.0	2.69@70.8	WillsWing
WillsWing Talon	0.89@38.6	2.69@75.6	WillsWing