To fly a glider, such as the ASK 21 included with X-Plane 10, you will need to be towed aloft by another aircraft. To do
so, first load your glider as usual (using the Open Aircraft dialog box, found in the Aircraft menu, or using the Quick
Flight Setup dialog, found in the File menu), then open the Aircraft & Situations dialog box (found in the Aircraft
menu). Here, you have two options. The Glider Tow button will load another aircraft (by default the Stinson L–5, but
this can be changed in the “Other Aircraft Profiles” box) to which your glider will be attached. This aircraft will pull
yours along behind it, and you will be able to release the line connecting you to the towplane at your desired altitude.
On the other hand, the Glider Winch button will set up a stationary winch on the ground which will quickly pull in a
wire attached to your glider, which you will release once you are 1500 feet or so above the ground. In either case, you
can release the tow line by pressing the space bar.
When using the towplane, you will start behind the plane with its engine running and ready to go. Releasing the
glider’s brakes (using the b key by default) commands the towplane to take off, dragging your glider with it.
The towplane, once in flight, will take the glider as high as you like. While being carried up to altitude, though, you
must keep your glider in formation behind the towplane. Pressing the space bar will release the line between the
aircraft, allowing you to soar freely.
Notice, of course, that until you have unhooked yourself, the tow rope connecting your glider to the towplane is
attached to your nose and the towplane’s tail. X-Plane models the real physics of this situation, so if your glider pulls
left, right, up, or down, it will drag the towplane’s tail in that direction. This could result in simply pulling the plane off
course, or ultimately in dragging the plane into a stall or spin. If that happens, things will get very complicated very
quickly—-the towplane (which will likely be crashing) will be dragging the glider with it! The dynamics of the resulting
crash are interesting if nothing else.
According to the FAA Glider Handbook, a glider pilot should keep the glider in one of two positions when being
towed to altitude. It should either be in a “low tow” position, wherein the glider is just below the wake from the
towplane, or it should be in a “high tow” position, just above the wake from the towplane. Hold this position carefully
to keep from dragging the towplane around!
A glider pilot must watch the wind and the slope of the terrain carefully to hold inside the upward-moving currents of
air, using the lift of the air flowing up the mountain slope to hold the craft aloft. With a good 25-knot wind set in the
simulator, you can get a nice, free elevator ride to 10,000 feet when flying along the windward side of a nice, steep
mountain. This is called ridge lift.
X-Plane will also model the columns of rising hot air, called thermals, that are useful for prolonging a glider flight. To
turn on the thermals, open the Weather dialog box from the Environment menu. Select the set weather uniformly
for the whole world radio button, then drag the thermal coverage slider up—15% coverage or more makes for a
nice flight. A 500 ft/min thermal climb rate is fine, but you can raise that value, too, if you like. Additionally, as you’re
starting out in gliders, you may want to keep the various wind speed, shear speed, and turbulence sliders set to
minimum.
Now, to take full advantage of both ridge lift and thermals, gliders have a unique instrument known as the total
energy variometer. This indicates your glider’s rate of climb or descent. You can see the visual representation of this
instrument in the panel (it is labeled “Total Energy” and is found towards the bottom of the panel in the ASK 21); if the
needle is above the center of the dial, you are climbing (perhaps due to ridge lift or a thermal), and if it is below the
center, you are falling. Even better, you can flip on the switch next to it labeled “Audio” in the instrument panel to get
auditory feedback from the variometer. If it is beeping, then the aircraft is in a nice updraft from the air following the
terrain. Circling in that area will let the glider ride the climbing air to altitude. When the variometer is emitting a steady
tone, the craft is in descending air—-the glider has been blown to the wrong side of the mountain, and a crash will
follow soon if you do not find a way out of that area!
To land the glider, simply circle down to runway level. The trick is to approach the runway with just enough speed to
set the craft down safely. Remember, pulling the speedbrakes in can help slow the craft down, but if it doesn’t have
enough speed to reach the landing strip, the glider has no way of generating thrust. Ideally, you will reach the runway
at just above stalling speed, but it’s always better to have too much speed (which you can burn off using the
speedbrakes) than too little.