Flytec
Wills Wing

Oz Report

Volume 4, Number 59
9 pm, Monday, March 13 2000

https://OzReport.com
"Toto, I have a feeling we're not in Kansas anymore."

to Table of Contentsto next topic Ah, competition, isn't it wonderful?

Mon, Mar 13 2000, 8:00:00 pm GMT

Florida|Ghostbuster|Malcolm Jones|Mark "Gibbo" Gibson|Mark Poustinchian|Quest Air|record|Wallaby Ranch

Mike Eberle at North American Flight Design has put up $3000 for the first pilot to fly a Ghostbuster 200 miles out of Quest Air.  Hmmm, I wonder who first came up with that specific idea?

Of course hang gliding and hang glider pilots benefit a great deal from this kind of encouragement.  It really focuses our attention and tells us that somebody cares.  Mike really deserves our thanks.

Back in ancient history, Malcolm Jones, set aside $1000 for the first pilot to fly from Wallaby Ranch to Georgia (still open). There are a bunch of other monetary prizes also (best flight in April, the state record, Women's longest, etc.). By the way, Malcolm is not the answer to the question above.

There will be money prizes at the Wallaby Open, and there is a slight chance of money prizes at the ACC.  Manufacturers and flight park owners will sponsor a number of the pilots flying at these meets.

It's really great to see these prizes, and everyone has at least some chance of grabbing the brass ring.  Albo, his dad, says that Gibbo will be out at Quest on Wednesday.  Maybe Flight Design would come up with a few hundred if I did it on their other rigid wing?

Speaking of long flights, Mark Poustinchian, «markpoustinchian», flew 163 miles the day after Gibbo flew 140 miles and landed in Georgia.  Mark got ¼ miles over the Georgia-Florida border, but had to come back to land safely.  The interesting thing about the flight was that he did it the hard way, not going for the little bit of Georgia that dives down into Florida.  You can read about it at: http://home.talkcity.com/PlayingFields/mpousti/index.html and see the track long at http://home.talkcity.com/playingfields/mpousti/Picture31000.html.

Discuss "Ah, competition, isn't it wonderful?" at the Oz Report forum   link»

Mon, Mar 13 2000, 3:00:01 pm EST

to Table of Contentsto next topic Faired down tubes

carbon fiber|CIVL|Felix Ruehle|Wills Wing

carbon fiber|CIVL|Felix Ruehle|John "Ole" Olson|Wills Wing

(?-i)John "Ole" Olson|carbon fiber|CIVL|Felix Ruehle|Wills Wing

carbon fiber|CIVL|Felix Ruehle|John "Ole" Olson|Wills Wing

Called Bob Trampenau, «seedwings», today to order some of his cool downtubes.  Found out that Felix Ruehle is supposed to be checking out a number of down tube sections at the University of Stuttgart wind tunnel.  I guess the Ukrainians are the only ones with access to a wind tunnel.  Felix has a piece Bob's down tubes for testing.  Our quick and dirty tests showed them to get an improvement over Fensterwald down tubes.

Bob says the he thinks he can reduce the size of the down tubes by 20%, and match the width of the Wills Wings carbon fiber down tubes.  This would allow inexpensive aluminum tubes to compete aerodynamically with $400 carbon fiber uprights.  I hope to hear more from Bob on this.

Speaking of carbon fiber uprights that are less than 22 millimeters in thickness, I have been trying all week to track down a vague rumor that CIVL executive committee (whatever they call it) has somehow altered the Class I safety specifications that the whole of CIVL passed at their very recent meeting (as I recall, unanimously).

I don't have a lead on whether this rumor is the slightest bit true, but if you do, please contact me and tell me the real story.

Discuss "Faired down tubes" at the Oz Report forum   link»

Mon, Mar 13 2000, 3:00:02 pm EST

to Table of Contentsto next topic Joe Greblo on No Flare Landings

Davis Straub|George Ferris|Joe Greblo|Wills Wing

I was very happy to receive a message from Joe Greblo after he read my series of articles on No Flare Landings.  Joe is a very well respected hang gliding instructor, among many other things, in southern California.

Joe had a set of notes that he sent, with the proviso that they weren't really finished, or ready for publication.  When George Ferris read them he thought they were great.  I really wanted to publish Joe's thoughts.

Well Joe and I cleaned up his notes a little bit, and while they are still a bit rough, they'll do for now.  I think that Joe really speaks to a revolution in our thinking about hang glider landings and I hope you will read his notes carefully.  Joe can be reached at «windsports».

Congratulations on your discovery and welcome to the world landing hang gliders without full flares.

As a flight instructor, this subject has plagued us for years and gotten worse with glider evolution of the past 15 years.  The historical solution to bad hang glider landings has been to try to increase the pilot skills to keep up with the higher wing loadings, taller and wider control bars, shorter chord lines, the lower twists, more rapid pitch rotations, relentless energy retention, etc.

You've noticed something that only a few instructors have been teaching for years.  That is that a modern hang glider should no longer be landed like a parachute.  This worked fine for standard Rogallos and lower aspect ration wings, but in retrospect, we probably should have abandoned this technique in 1980 with the introduction of gliders like the Wills Wing Harrier, Duck, UP Comet, etc.

Instead it would be safer in general to land hang gliders more like airplanes by "greasing them in", so to speak.  There's a bunch of reasons for this that take a bit of explaining, and I've not yet been able to put them in the form of a good article, but I'd be happy to give you a call and discuss them with you if you are interested.

It's rather encouraging to note that this (what I'll call more modern) landing technique has really taken hold at one of our flight parks (in an undisclosed location). About 30-40% of the pilots are landing this way now and they swear by it. Not as many whacks around the l/z.

The main problem I have with flaring at an angle of attack lower than stall is that this airspeed provides the wing with a slight surplus of energy that is occasionally converted to excessive, undesirable, altitude when coupled with incorrect flare timing, or an unpredictable gust of wind.  Stated differently, with this technique, as the pilot begins to flare, the wing will produce greater lift before the wing stalls and reduces lift.

The bad part here is if you get a gust at the moment of flare, your glider will climb to an altitude proportional to the velocity of the gust.  The second problem with this technique is that when timed properly, semi-prone and even prone positioned pilots are rewarded with successful landings.

1. This technique puts the pilot into a severely stalled angle of attack while at high wing loading.

2. This technique puts the pilot into a prone position (relative to the wing) during the highly loaded stall.

3. If we could greatly reduce wing loading during the stall, we could greatly reduce the stall speed

4. During stall, directional control is dramatically reduced.

5. If we could control the relative wind during the landing flare, we could reduce some of the negative aspects of the landing flare.  i.e. the magnitude of the stall break.

Since the beginnings of our sport, it has been taught that the perfect landing is one in which all forward ground speed is eliminated before the pilot's feet contact the ground.  As gliders evolved into wide, span efficient, high lift wings, perfect landings have become more and more difficult to achieve.

No single subject has occupied the minds of instructors and pilots more than that of "how to land a modern hang glider". There have been more articles, more lessons, more clinics, more dialogue, on this subject, perhaps than any other subject in hang gliding.  We have the "crescendo technique" and the "2-step flare". We've had articles on hand position, body position, flare timing, etc.  And what seems common to all this rhetoric is the realization that a good no-wind landing requires flaring the precise amount at exactly the right moment.  Too early and it's time for new downtubes.  Too late and your friends are wishing you luck (or yelling WHACK!)

Ah, that moment!  That elusive little moment.  You better not miss it or else!  If only we could broaden this moment, and give us a wide window of opportunity to flare the glider.  Naw, that's not possible, is it? You bet it is! And to understand how, one needs to look closely at 2 things.  How a hang glider stalls, and how landings have traditionally been taught.

For years, many instructors have taught pilots to begin their flare at an angle of attack that is lower than incipient stall (mush). In light winds, this flare is quite quick and dramatic, resulting in the landing position in which the pilot is in the prone body position relative to the keel as required to land on his/her feet.

At some point during this landing, the pilot has assumed a prone position relative to the keel.  In fact, this prone body position is a necessary component of a good zero wind landing.  If, then we must get prone sometime during this flare process, it's not surprising that some pilots assume the prone position sooner than others.

Hang gliders are designed to drop the nose when they stall.  That's a good thing and you wouldn't want it any other way.  Another fact is that the rate the glider pitches down during stall recovery, and the force of the nose down rotation, is related to angle of attack.  The higher the angle of attack in stall, the further downward and more powerfully the nose will rotate during recovery.  Based upon this we can certainly understand why pilots struggle more with no wind landings than when landing into a moderate breeze.

To further complicate things, hang gliders have evolved to reasonably high aspect ratios as compared to the easy to land gliders of the 1970's. And high aspect ratio wings rotate about their pitch axis much more quickly than low aspect wings (Pulses, Dreams, Falcons, etc). Manufacturers have tried to remedy these problems by locating the apex of the control bar further rearward giving the pilot more authority during the flare when the glider would like to powerfully recover from the extremely high angle of attack associated with the no wind flare.

But they have not found a way to prevent the glider from trying to rotate it's nose downward during this severe stall event as this is an important part of the gliders pitch stability.  We all know what would happen if you fully flared your glider at 1000 ft. agl (please don't do it to find out!) It will pitch down violently and uncontrollably and possibly tumble ass over teakettle!  But isn't this what we are trained to do when we land in no wind?  Of course it is!

Why doesn't the glider pitch down violently and uncontrollably and tumble during a no wind flare?  The answer; it simply doesn't have time.  Hopefully our feet are on the ground before it begins this process.  But don't be fooled, if your feet are not on the ground quickly, you can be assured that the glider will try to recover from this stall.  And if you give it the time and space, it will do it just as violently as it would at 1000 feet.

Whoaa Nelly!  But what would happen if you hooked into your glider in your l/z, ran with it on flat ground until your harness straps were tight and your glider lifting, and flared hard?  I'll tell you.  The nose easily remains up with little pitch down forces.  Even in zero wind!

Hmmm, in the first example, when the glider is at altitude and dramatically stalled, it pitches down with extreme force and magnitude, but in the second example it doesn't. What's different in these two examples?  Only wing loading and the direction of the relative wind (angle of attack)!

If, during your flare, you dramatically reduce wing loading and control the direction of the relative wind, you can eliminate the powerful forces of rotation about the pitch axis.  In doing so we can eliminate one of the major causes of the nose and control bar hitting the ground.

Another relationship between wing loading and the stall, is stall speed.  Stall speed increases with wing loading.  Reduce wing loading and you reduce stall speed.  If you could eliminate wing loading entirely, your wing could never stall!  If it never stalled, it would never pitch down in its attempt at stall recovery.  Hence, even with a very pitch stable wing, it would be easy to keep the nose up on landing.

Back to landing problems.  We recognize the time to flare as an elusive moment.  Can we broaden the moment so that we can flare early or late and not be penalized with a bad landing?  Unfortunately, the only way to flare early without the danger of climbing is to cause such a quick and complete flare action as to produce an accelerated stall.  Although this may be a valuable skill to possess, it is a difficult and dangerous task to practice.  Therefore few pilots will ever avail themselves of this useful skill, hence early flares will almost always increase your danger.  But we can eliminate the usual landing problems associated with flaring later, at slower airspeeds.

Many pilots who have tried flaring later than the "magic moment", find that they still have bad landings.  Most often this is caused by their expectation that the glider will rotate upward, ultimately placing them on their feet in the perfect stand-up (but prone with respect to the glider) position.  By waiting for the glider to drop the pilot onto his/her feet, the glider remains at a high wing loading through this dramatically deep stall.  Remember, high wing loading means high stall speed; and deep stall means quick and powerful stall recovery forces.  Since the pilot has waited until the glider is without excess energy, it will not climb the amount necessary to rotate the now prone pilot to his feet and he lands on his belly, or tries to run it with his feet too far behind him.

The solution requires 3 simple actions from the pilot.

1. Delay the flare by holding steady altitude (your feet 2 inches above the ground) in your ground skim until it cannot be held any longer.  This is when the glider truly begins to stall (mush) and it will settle you gently onto the first step of your run.  The fact that you've induced the onset of a stall will insure that the glider will not climb even with an unexpected gust.

2. Keep the feet under you, remain upright, and begin to run as soon as the first foot touches the ground.  This will unload the glider, eliminate it's high wing loading, and control the relative wind to provide a maximum angle of attack of 90 degrees as opposed to 180 degrees associated with the tail sliding flare.  This guarantees you will be on your feet in an effective running position and reduces the powerful and nasty stall behavior of the glider during the flare.

3. Accelerate your run and flare fully and completely at the moment the glider sets your weight on your foot.  With this technique, you will come to rest in only one or two steps.  If the terrain allows you to take more running steps, feel free to run out your landing with a gentler, more progressive flare.  If you desire not to flare fully, that's ok too as this technique allows pilots to utilize a complete range of flare magnitude.  They can flare fully if the wings are level and the terrain won't allow a run, they can flare slowly and progressively to stop the glider whenever they want to, or they can choose not to flare at all.

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Davis Straub
co-author of Windows 98 Secrets, and More Windows 98 Secrets, IDG Books
"The Jaws of Life for Windows 98 Users"
«davis»
http://www.davisstraub.com/secrets

The Oz Report, a near-daily, world wide hang gliding news ezine, with reports on competitions, pilot rankings, political issues, fly-ins, the latest technology, ultralight sailplanes, reader feedback and anything else from within the global HG community worthy of coverage. Hang gliding, paragliding, hang gliders, paragliders, aerotowing, hang glide, paraglide, platform towing, competitions, fly-ins. Hang gliding and paragliding news from around the world, by Davis Straub.

Discuss "Joe Greblo on No Flare Landings" at the Oz Report forum   link»

The Oz Report, a near-daily, world wide hang gliding news ezine, with reports on competitions, pilot rankings, political issues, fly-ins, the latest technology, ultralight sailplanes, reader feedback and anything else from within the global HG community worthy of coverage. Hang gliding, paragliding, hang gliders, paragliders, aerotowing, hang glide, paraglide, platform towing, competitions, fly-ins. Hang gliding and paragliding news from around the world, by Davis Straub.

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