Your connection with the sky

Soaring – Sailplanes

All aircraft are beautiful in their own way but sailplanes are arguably the most visually stunning. Because sailplanes are raced and "racing improves the breed", the pursuit of pure, uncompromising performance has resulted in objects of unsurpassed beauty. They have been refined through thousands of prototypes until designers settled on long, thin wings, a "pod and boom" fuselage and a "T" tail. The result is beautiful, fast and has superb handling qualities.

Since a glider by definition has no engine, its phenomenal flight performance depends entirely on very sophisticated aerodynamics. Surfaces are mirror smooth and every curve has been calculated by supercomputers running Computational Fluid Dynamics (CFD) software to minimize drag.

Two numbers are used as a shorthand to describe sailplane performance - the minimum rate of descent and the maximum glide ratio or Lift over Drag (L/D). The best numbers are now under 100 FPM and over 70:1. Astute glider pilots know these are inadequate and the real measure is the "Polar Curve" or a graph of sinking speed vs. airspeed. The designer wants to minimize sink rate at all speeds.

Now that I've mentioned Polar Curves, here's one of the most counter-intuitive concepts in aviation. Racing sailplanes have huge water tanks in the wings for ballast. Why? Increasing the gliders weight shifts the polar curve down and to the right along a tangent drawn from the origin of the graph. This increases the sink rate a little at low speeds but dramatically REDUCES the sink rate at high speeds. Since a racing glider spends more than 80% of its time at high speeds the net result is that a heavy glider is a fast glider even considering the longer time climbing in thermals. If the lift gets weak and always before landing, the pilot will dump the water in flight creating a beautiful contrail.

So, who actually designs sailplanes? Many are designed and prototypes built by university students in German "Akafliegs" or academic flying groups. A sailplane can be basis of a students doctoral thesis. If the prototype is good enough, it may enter series production. No other country has developed Akafliegs to the same degree so Germany is the worlds largest maker of gliders, although the Eastern European countries are coming on strong.

So how much do gliders cost? Like all 'big boys toys' these can cost a lot if you're so inclined but excellent used ones can be had for a little more than $20,000. A good listing of used gliders along with lots of new "glider stuff" can be seen at: www.wingsandwheels.com. Scroll down to find the used glider listing.

If you own a glider, where do you keep it? An airplane has to be either left out in the weather or kept in an expensive hangar. Most owners put gliders in trailers and bring them home. Enclosed trailers have all the weather protection of hangars but none of the cost. Assembly and disassembly (Rigging and de-rigging in the vernacular) can be done in a few minutes by one person with the right rigging aids. If you're really in a hurry watch how these Finnish folks do it. See: http://www.youtube.com/watch?v=Huk_WOxk1oc#

If soaring interests you, visit www.SSA.org and click on "Where to Fly".

Next time the big question: "But,you can't go around?" All about landing gliders.

5 Responses to “Soaring – Sailplanes”

  1. Thank you for the kind words about gliders ! They are a wonderful way to learn to fly and make flying anything powered that much easier. One really has to be careful because they really are addictive !

  2. James Karcher Says:
    March 13th, 2009 at 8:20 am

    I first became interested in gliders because pictures I saw in a National Geographics article over 40 years ago were so beautiful. White slender wings against a brilliant blue sky. I began SEL flying lessons so I could ultimately fly gliders. That is the most efficient way in terms of cost if you want to be qualified to fly both powered and unpowered aircraft, but starting in gliders may be the road to being a better pilot. You cannot help but understand aerodynamics, develop good aviation judgment, and hone excellent stick and rudder skills if you fly gliders.

    Gliders don't work for business trips, but for sheer recreation they cannot be beat, at least on a day with lift. Every flight provides challenge - challenge to stay airborne, challenge to fly farther or faster, or simply the challenge to fly as efficiently and as technically correct as possible. And when two gliders are airborne at once, there is often at least some hint of competition between the pilots.

    One should realize, however, that in addition to your own flight there is usually some overhead required in terms of helping other pilots assemble and disassemble their aircraft, serving as ground crew, or flying the tow plane. A glider flight often entails a day at a country airport rather than the quick ninety minutes spent in and around a busy field for the typical powered flight. But, can you think of a better way to spend a beautiful spring day?

  3. Richard Bailey Says:
    March 13th, 2009 at 11:10 am

    For those who plan to fly both gliders and SEL,it is likely more cost effective to start in gliders. The cost of glider training is less than that of SEL, and often quicker. When one gets to engines, he/she will already know how to fly. This way, one can spend less time in the more expensive training.

  4. Warren Whitford Says:
    March 13th, 2009 at 11:56 am

    I got my power license in the early '70s. Then in the '90s becamse a tow pilot for a glider club. I have always been interested in gliders so I got my private, then commercial glider license. Now I have let my medical go and fly mostly gliders and once in a while a Cub. Gliders are much less expensive to fly and they are a lot of fun. It's the only thing I can afford to fly anymore, but that's ok because I love flying them. There's nothing like the feeling of circling in a thermal climbing thousands of feet with no engine. It's beautiful! You'll learn a lot of valuable things flying gliders. I don't race gliders, just fly them for fun, and is it ever fun! Glad to see some things about soaring on the AOPA website. If you try it you'll love it!

  5. I own a Ventus 2cmx auxiliary powered sailplane. It’s a regular sailplane with a slight advantage. It has a retractable engine which can be used for takeoffs and then is stowed for pure soaring flight. The motor is only used to get out of the airport environment the same way a sailboat uses it’s motor to get out of the harbor. In fact the motor is so small that the same sailplane, with it uncompromised performance of over a 50:1 glide ratio, can be bought with or without an engine installed.
    On my last flight I used 1 quart of fuel and flew 300 miles using thermals to climb and with my 50:1 glide flying as far as 50 miles for every mile of climb attained in the thermal. That’s 1200 miles to the gallon! And all at an average speed of 60 miles per hour. For pure satisfaction there’s nothing like soaring!

Leave a Reply

*