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.

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: Assemble and fly a sailplane in seconds

If soaring interests you, visit: Soaring Society of America and click on "Where to Fly".

Click: 12 instruction videos on flying gliders, sailplanes and powered paragliders