Your connection with the sky

Introduction to soaring – what are the possibilities?

As flying becomes more expensive, aviation enthusiasts are taking a long look at a form of recreational flying that uses the absolute minimum of fuel and has a tiny environmental footprint.

This Blog is about Soaring. That's the "Art, Science and Sport" of flying powerless sailplanes to great heights and long distances at astonishing speed.

It's a "Sport" since we do it for fun. It's a "Science" since, like any pilot, you need to know some things about aerodynamics and meteorology. It's also an "Art" because Mother Nature keeps reminding us how little we really know.

Soaring goes back more than a hundred years - right back to the dawn of flight.

"When gliding operators have attained greater skill, they can maintain themselves in the air for hours at a time."— Wilbur Wright, 1901

"There is no sport equal to that which aviators enjoy while being carried through the air on great white wings." — Wilbur Wright, 1905

Wilbur was more than a little prophetic. In 2008, approximately 20,000 US glider pilots flew their "Great White Wings" over 60,000 hours including 1.8 million miles flown cross country. That's a lot of flying without consuming Jet A or AVGAS.

We know this is so because they submitted secure GPS logs to the Online Contest. See: www.ssa.org > "Sailplane Racing" > "Online contest" scroll down and click "here" for a list of today's flights. To see a map of a flight, click on the blue dot on the right.

I'm guessing a few of you readers are wondering how can a glider without an engine can fly cross country?

Current high performance gliders have a glide ratio of around 50:1 as compared to the typical light airplane's 7:1 glide. That means from 1 mile AGL a sailplane can silently glide nearly 50 miles - much further if the pilot can find "lift".

When flown slowly at an airspeed corresponding to the least rate of descent, these gliders will sink at less than 100 FPM. Gliding cross country there is no sensation the glider is descending.

For example, on March 27th of 2008, Jim Payne flew his German made ASW-27 1,027 miles non-stop at an average 107 MPH from Rosamond Airpark, CA to near Truckee, CA and back landing on the departure runway after a flight of over 11 hours. There were 22 other US glider flights in 2008 that exceeded 600 miles.

You might ask, "1000 miles at over 100MPH with no engine, how exactly was that done?"

Sailplanes aren't totally powerless. They have a pilot who (hopefully) knows a little about soaring weather and, in the case of soaring, that knowledge is literally power.

Soaring weather is all about finding "lift", or rising air, which can lift a glider to great heights restoring the altitude lost in long glides. It's a process of climbing and gliding again and again as you move cross country.

Jim Payne flew over California's Sierra Nevada mountain range where lift is both extremely strong and widespread. On occasion, Jim covered over 100 miles on a single glide.

In strong conditions like these the probability of finding the next source of lift after a long glide exceeds 100%. Most pilots are choosy and will pass up all but the strongest updrafts.

What about this "lift". How does it work?

If a glider sinks at 100 FPM but the air around it is rising at 1000 FPM, the glider will climb at 900 FPM as long as it stays in the rising air. The trick is to stay in "lift" and out of "sink".

I'll write more about the kinds of lift and how you find it (an how to avoid "sink") in the next installment.

Meanwhile, take a look at www.ssa.org and click "About soaring" then "Where to Fly".

4 Responses to “Introduction to soaring – what are the possibilities?”

  1. Jim McSherry Says:
    March 14th, 2009 at 7:47 pm

    Great description of a truly beautiful activity; I transitioned from power to soaring two summers ago, and still am building skill in that field, even as I instruct power pilots.
    My only quibble is that no event has a "probability [that] exceeds 100%" . Only something that is absolutely certain (like a released object falling to Earth) is a 100% probability; there is no greater value possible. The "probability of finding lift" may _approach_ 100% in such wonderful conditions, but there is always the small chance that even when the lift is present, he won't find it.
    Now, no one should use this trivial point to keep them from flying sailplanes - it is just too much fun to miss. It is merely the nit-picking of a retired science teacher.
    The opportunity to find yourself alone in the sky with an orbiting eagle, as I did last summer, is a treasure not to be missed; there is no satisfaction greater than riding up in a thermal and gliding gracefully through the sky for an hour or so before touching back down in the same field where you left your buddies at departure.
    As they say, "Try it, you'll like it."

    Jim McSherry

  2. Bill Daniels Says:
    March 14th, 2009 at 9:05 pm

    I probably should have said the probability of finding a thermal exceeds unity on a good soaring day.

    Looking at my GPS logs with glide analysis software like SeeYou,(http://www.naviter.si/) it seems I pass up roughly 5 out of 6 thermals. Either they aren't strong enough or I'm already at 17,500 feet and can't use them. I just slow down in the lift. It's called "bumping" thermals.

    There's nothing special about me, all glider pilots do this.

  3. Jim McSherry Says:
    April 4th, 2009 at 9:36 pm

    No, you shouldn't say that the probability of anything exceeds unity, ever. Even when there are plenty of thermals around, there is no guarantee that you will find even one of them - - I can attest to that. You are clearly a far more experienced glider pilot than I, but that's no excuse to misuse your math. The only certainty (100% probable, but no more) is that the sailplane will return to Earth.

  4. Bill Daniels Says:
    April 5th, 2009 at 10:39 am

    So, help me out here. How should I state this?

    That on a good day a high performance sailplane will find not just one but many thermals on each glide is beyond question. One need only analyze the IGC files downloaded from the OLC to see this.

    There are a few inferred qualifiers here. One is that the pilot doesn't hang around the home airfield. Another is that the pilot must direct the path of the glider towards areas likely to generate lift.

    The first qualifier is important. Even on a VERY good day there will be times when no thermals can be found within a 3 mile radius of home base.

    A pilot striking off cross country will be constantly sampling new air which greatly improves his chances. It's like shooting a rifle into a thick forest with overlapping tree trunks - what are the chances of NOT hitting a tree?

    That leaves the bit about directing the gliders path. Thermals will lift a wing and turn the glider away. If you just let the glider find its own way, it will wander around thermals missing all of them.

    I'd love to fly with you sometime and demonstrate this.

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