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I am using X-Plane learning some basics in aviation. Currently, I'm using the glider so I can focus on flying and not engines.

I've heard of gliders being able to catch drafts so as to keep continuous flight. Is there a rule to be able to do this? I thought by riding with the wind and occasionally intersecting I might keep up the energy, but it does not seem to work that way.

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    $\begingroup$ This is going to depend on whether and how accurately your simulator simulates thermals, ridge lift, &c. It can be done in real life. Maybe you should start with a good book on the basics of soaring? $\endgroup$
    – jamesqf
    Dec 13, 2016 at 4:39
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    $\begingroup$ Gliders do NOT rely on (horizontal) wind to stay airborne. You want to read up on adiabatic processes and thermals instead. As for focusing on flying and not engines, sure you do not have to learn about engines to fly gliders, but what you save on theory about engines you will have to make up for in theory about meteorology. Make no mistake, flying gliders is a complicated topic. $\endgroup$
    – 60levelchange
    Dec 13, 2016 at 5:29

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You need some inhomogeneity to extract energy. For gliders there are three basic ways to do that:

  1. Thermals: The sun heats up the ground which in turn heats up the air above it. Hotter air is lighter and rises up. It keeps rising as long as the lapse rate of the atmosphere is above the adiabatic rate. This means that three conditions must be met for thermals to occur:
    1.1 Sunshine
    1.2 Sufficient atmospheric lability
    1.3 Ground that easily heats up, such as forest or sand.
  2. Ridge lift: Air streams across a hill and rises up on the windward side. Behind mountain ranges you might also find lee waves, an atmospheric oscillation caused by wind blowing across a mountain.
  3. Dynamic soaring: Here the wind gradient in the atmospheric boundary layer is exploited by flying turns while pulling up when turning into a headwind and diving down when turning into a tailwind. This is currently only used by Albatrosses and has been experimented with by Ingo Renner, but is much too stressful for human pilots if done for extended periods.

Look at the variometer in your glider and try to fly circles when you see an indication of rising air. Tighten the circle when climb rate decreases and flatten it when it increases in order to center the glider in the thermal.

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  • $\begingroup$ By 'lee wave', do you mean gravity wave (a.k.a. mountain wave) as seen here: youtube.com/watch?v=yXnkzeCU3bE which gives you terrifc lift but also very dangerous downdraft? There is also lift from 'convergence' where two winds meet, typically a sea breeze bumping up against the met wind: en.wikipedia.org/wiki/Convergence_zone. I doubt any desktop flight sim will simulate these $\endgroup$
    – Dave Gremlin
    Dec 13, 2016 at 23:47
  • $\begingroup$ @DaveGremlin: I never heard the term gravity wave for lee waves, but yes, mountain wave is another word for lee wave. Wikipedia uses this term, so I used it here, too, since I linked to the Wikipedia article. Convergence zones give too little vertical speed; I have never heard that they can be used for gliding. $\endgroup$
    – Peter Kämpf
    Dec 14, 2016 at 7:39
  • $\begingroup$ @DaveGremlin. "gravity wave" just means one of the restoring forces driving the oscillation is gravity, and that is true of most transverse waves in fluids and on fluid surfaces, so e.g. waves on water are also "gravity waves". In contrast "lee wave" indicates the wave is formed on the lee, downwind, side of an obstacle due to the obstacle disturbing the flow, so it is a more specific term here. $\endgroup$
    – Jan Hudec
    Dec 16, 2016 at 21:26
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Gliders do not fly with a constant elevation, the goal with gliding is to find updrafts and ride them as high as possible, then trading altitude for distance until another updraft can be found. So the flight profile of a glider goes up and down, it does not stay constant.

Simulators are good for learning processes but not so good for learning the aspects of flying that require more feel, and gliding is definitely a feel thing. Glider pilots learn to recognize where thermals are active and ride them up, not something you'll get in x-plane or any other simulator I've tried. I would suggest powered flight as it's more realistic and you'll learn more.

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