Frequently Asked Questions about Polar Explorer
Glider Definition in Polar Explorer
Running Polar Explorer
Q What versions of Windows will Polar Explorer 2.2 run under?
A You can run Polar Explorer directly on Windows 3.1 to Windows XP.
Q Can I run Polar Explorer under Mac OS X or Linux?
A Although at the time of this writing I haven't tested this, I believe that you can do this through DOSBox DOS-emulator. You can download free DOSBox for Mac OS X, Linux and a bunch of other operating systems from http://dosbox.sourceforge.net/download.php?main=1
Q Can Polar Explorer be displayed in a window when in graphics mode?
A Although Windows (especially XP)
doesn't support DOS graphics mode in a window natively, there is a way to do
this by running Polar Explorer through DOSBox DOS-emulator. You can
download free DOSBox from
Q Can I print or capture the graphics display from Polar Explorer?
A If you are running Polar Explorer
under Windows 98 or earlier (with or without DOSBox) you can use
<Shift>+<Print Screen> key combination or <Alt>+<Print Screen> when you have
the desired graph on screen. This will send the screen graphics into the
Windows clipboard, from which you can then insert it into any image editing
program (such as MS Paint) or directly into Word.
Q Can I set Polar Explorer's graphic display with to white background?
A You can do this by selecting Options | Force mono graph (Yes) and then Options | Colors | Graph | Inverse.
Q Can I export Polar Explorer's graphs to an Excel spreadsheet?
A In order to do this, do a Table print to a text file (selected under Printing options). Then import the table from the text file into Excel and use it to recreate the graph.
Glider Definition in Polar Explorer
Q How is a glider defined in Polar Explorer?
A A glider is defined by a few geometric parameters (e.g. wing span, wing area), aerodynamic parameters (e.g. aspect ratio correction factor), and anywhere between 3 and 30 points on the polar curve. The polar curve can be a speed - sink polar, or one of 3 different variations of a CL-CD (lift coefficient - drag coefficient) polar. Once entered, the polar curve can be converted from one type to any other.
Q In what units of measure should a glider polar be entered?
A Any combination of supported units of measure is permitted (Options | Units). For instance, you can enter speed in m/s and sink in fpm.
Q If a glider is entered in one set of units, can it be converted to another?
A Unit conversion in Polar Explorer is very simple, and you can convert glider data from one set of units to any other set of units through Options | Units. The results of the conversion are instantly shown on the screen.
Q How does Polar Explorer approximate a polar curve?
A It draws a smooth piece-wise double parabolic curve through every V-W or CL-CD point on the polar curve.
Q Can Polar Explorer process irregular polars?
A Polar Explorer goes to great lengths to accommodate and correctly process almost any possible and impossible glider polar. If a polar has dents, knees or bulges, Polar Explorer will take them all into account when calculating the speed-to-fly, cross country speed, circling performance, etc.
Q How long does it typically take to enter a new polar?
A For instance, if you have a table with 20 points on a speed polar, it should take 5-10 minutes to enter the points and iron out unwanted irregularities.
Q Do I have to enter the glider data every time I run Polar Explorer?
A No. The data defining a glider can be stored in a glider library. One library can store up to 500 gliders, and you can use more than one library.
Q Does Polar Explorer come with some glider examples already entered?
A It already comes with a fairly large library of polars (see Polar_Explorer_Short_Guide.pdf). Most of the polars are based on flight measurements by DLR institute in Germany and Richard Johnson in U.S.A. There are also some factory polars.
Q What can be done with the gliders that are already in the library?
A Any glider in a library can be: renamed, edited, deleted from the library and copied to another library. (The same can be done to any sheet in the sheet library.)
Polar Explorer's Calculations
Q What kind of performance can Polar Explorer calculate?
A It can calculate the following performance curves, shown here grouped into five categories:
Q Which parameters can be varied in the performance calculations for any given glider?
A Any combination of the following parameters can be varied:
Q What is the accuracy of Polar Explorer calculations?
A It normally calculates only a
certain number of discreet points on the performance curves, and then draws
a smooth curve through those points.
Q What is the accuracy of Polar Explorer graph display?
A Graph display precision can be set
separately to low, medium, high, or straight-line. It is independent of the
calculation precision, and it determines how the program shows the curves on
the screen. When the precision is higher, the performance curves are drawn
more accurately, and therefore slower.
Q When are results shown in equivalent airspeed (EAS) and when in true airspeed (TAS)?
A Horizontal speed (V) and vertical speed (W) can be both shown either as EAS or as TAS by setting the V equivalent and W equivalent parameters on the main sheet to Yes for EAS or No for TAS.
Q Can results of the calculations be shown in different units?
A The results can be shown in any combination of units that are available in the Options | Units window.
Q Does Polar Explorer account for the changes in Reynolds number?
A Polar Explorer approximates the Reynolds number influence on the viscous drag coefficient through the Reynolds number exponent that is a part of glider definition data.
Q How is the custom atmosphere model defined?
A It is defined by setting the values of pressure and temperature at zero altitude, and giving the temperature at up to 5 more levels. The laps rate in each segment is assumed constant. The gas constant for air can also be modified to simulate the effect of humidity.
Q How is circling performance calculated?
A Polar Explorer can calculate circling performance in 4 different modes:
Q How is climb performance calculated?
A Polar Explorer first calculates the optimum circling performance (see above). Then, it determines the circling radius for which the maximum rate of climb is achieved. Polar Explorer does this for different thermal strengths, so the climb rate varies from 0 to the maximum desired climb rate.
Q How does Polar Explorer calculate average cross-country speed?
A It calculates it by varying climb rate, or by varying thermal strength and calculating the corresponding climb rate. In addition to altitude, glider performance and wing loading, it takes into account horizontal wind, updraft movement (drift), vertical movement of the airmass between the updrafts and the McCready speed ring setting.
Q Can I use Polar Explorer to plan or analyze a cross-country flight?
A You can use Polar Explorer to get the following information:
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