FS2k2 Glide Computer Polars

Max Roodveldt's L-Nav

Max's rendition of the Cambridge Aero Instruments L-Nav is the finest glide computer available for FS. It can load polar data specific to the glider in which it is installed (although the selection of polar is up to the pilot — see usage instructions below) and use it to calculate and display real-time speed-to-fly, glide slope, altitude required to reach turnpoint and other glide information.

The table below lists glide information for various gliders. The first column contains the L-Nav polar for each which can be copied-and-pasted for use with the L-Nav gauge as explained below. The other columns, from left to right are: stall speed, minimum sink rate, speed for minimum sink, maximum glide ratio, speed for maximum glide, speed-to-fly (stf) for L-Nav Mac Cready settings of 1.0, 1.5, 2.0 and 2.5 meters/sec. All speeds are in knots, sink rate is in feet per minute, Mac Cready settings are in meters/sec (as in L-Nav) although the speed-to-fly for each setting is shown here in knots. All data is corrected for sea-level standard attmosphere, and represents the zero-balast (dry) weight of each glider.

To install: the first column in each line is one polar. Paste the polar into <FS_ROOT>\LNAV_polarlist.dat using a plain-text editor. Each line in LNAV_polarlist.dat should contain one polar in it's entirety.

To use: The L-Nav will not detect which polar to use automatically and there is no way from the cockpit to see which one is in use. Before your flight, launch Max's Flight Viewer and click the "polars" button on the far-left (it has a picture of a curve on it). The polar window opens displaying the list of polars. Use the lower row of arrow buttons to move through the list. When the polar you want to use is shown in the lower, single-line text box, click the "Select" button. This button sends the current polar to the L-Nav. You can then close the polar window and quit the Viewer (although you may also want to load a task into the GPS while you're there). To verify which polar is currently in use, simply vew the LNAV_polar.dat file which resides at the top level of your FS installation.

THIS SOFTWARE IS PROVIDED BY THE AUTHOR “AS IS” WITHOUT ANY WARRANTIES. Modification, redistribution, bundling allowed provided that all of the conditions in the license are met. See the license for important details and disclaimer.

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Copyright © 2004 Kris Feldmann