http://t3d2.sourceforge.net/PGXCOPT/index.html Last upated 03 Dec 2009
The Speed to Fly theory from the sailplane environment assumes a vertical climb in a thermal.
While in a Paraglider in a flatland cross country down wind flight, we also cover distance while thermalling and drifting with the thermal.
S2FV2 calculates different scenarions, taking into account different wind speed at altitude and different lift profiles.
Code calculation example ....
Launch in a 18km/h wind
Release at 150m.
The first 500m are a 1m/s average climb.
The next layer from 500m to 1000m is a 2m/s average and the wind is 27 km/h.
Then we climb from 1000m to 2000m AGL and we have an average of 3 m/s
with a windspeed of 36km/h.
From 2000m to 2500m we climb with 2 m/s in a 45km/h wind.
And then we climb with 1m/s from 2500m into the top of the thermal that ends at 3000m. And the wind is 54km/h in that level.
Now we got 3 options
- leaving at 2000m when the climb drops below 2 m/s
- leaving at 2500m when the climb drops below 1 m/s
- leaving a the top of thermal
And we got the option to fly to the next thermal using
- trim speed or
- 50 percent bar or
- 100 percent bar
While gliding I assume an average sink of 1m/s by the air plus the sink by the
glider.
And we glide to the previous winch release height of 150m and then would find
another thermal.
The code compares a entry level DHV-2 wing with a competition wing 3+ .
What combination will give the best speed and get you back to cloudbase the quickest?
And what combination is the worst way to fly???
This Java Applet lets you compare different scenarios.
On the left side is 5 choices of different pre-prepared wind and lift profiles.
You can choose one and the sliders below will change their values.
Or you can then change the sliders to values of wind speed and average climbrates you want to try out.
All values are meter per seconds (m/s).
The 5 sliders represent different layers of the air. Windspeed and average lift in a thermal for that layer.
Then press the Apply button in the top.
Altitude and distance are not to scale.
Besides the Applet code which runs in the window above, one cn download the JAVA source and run it as a JAVA program.
The code generates a html document. And example of the results can be viewed here
A more detail trace of what gets calculated can be found here in text file format.
JAVA Source Code available at https://sourceforge.net/projects/t3d2/ in the PGXCOPT folder