Safe hang gliding launches REDUX

Several months ago we ran an article on safe hang gliding launch technique. Did it affect anything? Who knows? But at the recent Tennessee Tree Toppers Team Challenge at Hensen’s Gap, near Chattanooga, we conducted a launch seminar that had everyone expressing interest and finding some surprises.

I wish to thank Cliff Rice for taking the sequential photos that accompany this article and Keith Atkins for taking the videos and supplying them to me on disc. May your launches always be impeccable.

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We filmed each pilot’s launch and did some in-depth viewing and reviewing. It was clear that a wide variety of techniques exist and that most pilots had no idea of their exact procedures through the entire launch process. A number of pilots reported that after changing their technique during the competition week, they felt an improvement in both security and control. After the meet I looked at the photo sequences and the videos in much more detail and noticed several important factors I would like to pass along.

To begin, let’s define the parameters of a perfect launch technique. We all can probably agree that a launch method that holds the glider securely and maintains control throughout the launch process and holds the proper attitude and transitions to prone flying, without a major change of attitude, would qualify. Perhaps the most important safety factor is reaching good flying airspeed and preventing the nose from rising or popping during the full launch event. With this ideal in mind, we will look at a number of launches.

The Launches

The first thing that struck me when I looked at the 87 videos and nearly 500 photos was the great variety in technique. Here is a list of the main ones: 1. Modified beer bottle or pistol grip. 2. Grapevine grip changing to pistol grip early-on in the run. 3. Grapevine grip changing to pistol at the end of the run. 4. Grapevine grip held all the way (note, if the reader does not know these different grips, see page 58 of our Hang Gliding Training Manual). There are other techniques, such as the inside grip, but I didn’t see any of these in the videos.

Now let’s rate the four methods in view of our ideal technique.

1. The pistol grip is somewhat common because that is the way most pilots learn to launch at the training hill. The modified method has the pilot sliding the hands down along the uprights so the arms are fairly straight and the hands are below the waist (the beginner pistol grip has the arms bent almost 90 degrees and the hands above the waist—like holding a pistol). This grip requires no transition during the run and only a drop to the base tube once the pilot is airborne. The problem with this grip is it doesn’t afford as much roll control while standing and during the launch run. Those who use this grip may argue otherwise, but as someone in the launch seminar pointed out, how does everyone carry his/her glider off the field in a windy, gusty situation? With the grapevine grip, of course.

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Photo 1

Photo 1 shows a launch with this grip. This result is highly undesirable. Part of the problem is that the uprights are far down on the pilot’s upper arm, resulting in less control and an inability to push the glider with the shoulders. The push comes from lower on the uprights—thus, the greater tendency to rotate the nose upward. I see this in most launches that start with the pistol grip. Note: the colors of gliders have been changed in the photos, except for the pilots whom I identify.

If you think you recognize a pilot using a faulty technique, you are mistaken.

I have seen some intermediate pilots use the true pistol grip, but by the time they graduate to heavier gliders they probably have to modify the grip so that the glider rests properly on their upper arm. No doubt some pilots using this grip learn it by themselves. This situation points out the lack of training we have available to pilots moving away from the training hill and into higher performance equipment.

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Sequence 2 (and 3) - Grapevine start, early switch to pistol.


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2. Grapevine start, early switch to pistol. Of all the launch methods, this one is perhaps the most dangerous, yet it seems to be the most common. In this process, the pilot starts out holding the uprights in the grapevine, and then flips the hands to the pistol grip somewhere during the run. The danger is that a gust may hit during the (run, but, even more important, more-often-than-not a nose-up input occurs when the pilot switches the hand position. This action is grave and worth taking time to analyze. The photo sequence 2 and photo sequence 3 illustrate this clearly. In the second sequence, the glider’s attitude is increased by about 15 degrees. You can see this by comparing the keel positions. In many instances, the pilot switches his hands before the harness straps are tight, so the only points of contact with the glider are the hands and lower forearms.

The problem with such an increase in attitude is that it kisses a stall. In gusty conditions a near-stall can be turned into a stall by a variation in the air. A stall can result in a turn back into the hill and disaster. As Mike Barber pointed out in the seminar, it’s not a matter of if, but when. Meaning: if you are performing launches like those illustrated, you will eventually have an accident. If that doesn’t make the gentle reader sit up and take note, perhaps he/she better change his/her prescription.

Here’s another sobering fact: by viewing all the videos in this and previous seminars I have conducted, I would estimate at least 80% of all pilots use this faulty launch technique. Many of those who do this early hand-flip do not pop the nose as dramatically as the videos show (thanks goddess), so they get away with it for years. But it is a bogie waiting to pounce.

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3. Grapevine start, late flip to pistol. This technique I (and the perpetrators) can live with. With this method, the pilot starts in the grapevine, continues it through the run, then flips the hand to the pistol grip only when he or she is nearly picked off the ground and going prone. The pilot switches the hand position, because it may feel more natural or he wants to prone out before dropping hands to the base tube. Photo sequence 4.


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Photo 5

In any case, the later the switch, the better. In some of the photos it is clear that the pilot begins switching the hand position as soon as the harness main straps tighten. The problem here is that the straps are well behind the glider’s center of gravity, so the net effect of hands pushing and straps pulling is a nose-up action. Photo 5 clearly shows this effect.

The only problem with the late switch is that switching may be taking place when a gust hits. Think of driving a truck over a rutted road and opening your grip on the wheel, just as you hit a Texas pothole. To be sure, most of the folks flipping hands in this manner do so in a way that their palm pads and forearms remain in contact with the uprights during the process. But less than 100% grip is less than 100%.

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Photo 7

4. The full grapevine. With this method the pilot keeps his hands in the grapevine grip all the way until it’s time to drop the hands to the base tube. This is the recommended method in most situations, for it is the method that most nearly meets our ideal. It affords maximum control throughout the entire launch process. Photo 6 and photo 7 show pilots in the air with their hands still in the grapevine position, ready to drop to the base bar. The position may look awkward, but it isn’t. In fact, the pilots’ arms look rather like the wings of an eagle, or at least a hawk.

Some examples of pilots at the Team Challenge who use this technique are Mike Barber, Terry Presley, Lucas Ridley (flex wings), Ollie Gregory, Mark Stump and Kathy Lee (rigid wings). Photo sequence 8 shows Terry’s launch in absolutely still winds.

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Photo Sequence 8

Notice that he uses a modified grapevine grip with the index finger along the upright, which later moves to the front of the upright. This is a nice trick.

OBSERVATIONS
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Photo Sequence 9

If you pay close attention to Mike’s hands in his video, you can see something interesting: he slides them down the uprights once the glider is lifting and his straps are tight (giving another point of control). Interestingly enough, Mike didn’t know he was doing this. But it makes sense, because this allows the hands to stay in the grapevine grip without too much turning of the wrists. The way to do this is to let one hand slip at a time so control is maximized. This technique is especially useful if you use a back plate harness, for the slider on these harnesses let the main straps move up considerably, and the glider rises correspondingly higher before the straps tighten. In fact, pilots without back-plate harnesses will find that the main straps get tighter sooner in the run, and they can simply let the glider rise while maintaining the same grip position. By looking at Terry’s photo sequence, you can see that his hand has also moved down the upright. It started about 1/3 of the way up and ended up about 1/4 of the way up. Another pilot demonstrates this method even more dramatically. In photo sequence 9 his hands move down from about 1/3 of the way up the upright to about 1/5 of the way up.

Rigid wings tend to be a special case. We had many in this meet, so I got a chance to analyze lots of stiff launches. In most cases the pilots started with their hands higher on the uprights, compared to the flex-wing starting positions, so that the uprights were almost on top of the shoulders. This position makes it easier to heft the gliders’ greater weight. The compromise would mean less control if weight shift was the means, but pitch is easy with a rigid, and the aerodynamic controls take care of roll. So, with the hands in a relatively high starting position, you would think the pilot would flip them during the run, but they often don’t, because they have an excess of control. Also, having their hands almost awkwardly high is no problem once the glider lifts.

I looked at the photos and videos that captured two of my launches. I was surprised to see that I used a varied technique. When the wind was zero, and I was in a dive for airspeed, I switched my left hand to push out just before dropping it to the base tube. When the wind was blowing about 5 to 8, I maintained the grapevine until it was time to drop hands.Then I dropped my right hand first. In examining my launches, I realize that I vary them according to the conditions. On steep launches I keep the nose lower; on still launches I run much further and lean into the glider more. In gusty conditions I have a firm grapevine grip all the way through to the bitter end.

A final matter I could determine from the photo and video sequences is that it takes up to ten steps to fully fill the sails on a flex wing glider in still air—depending on the nose attitude, the length of stride and acceleration. Think of how important it is to be controlling the glider throughout this entire process. The ramp at Hensen’s Gap is forgiving to a fault. You can hop off there with one leg and have a good launch. There is plenty of dive-out clearance for the weak runners or nose-poppers. But all our launch sites aren’t so kind. At the other end of the spectrum, a windy, gusty launch (read thermals) can discombobulate our wings and greatly hinder control along the way. It behooves all of us to have the perfect full-control technique outlined above.

What can you and I do to keep our launches on an even keel? The first thing is to find out what our technique really is. The best way to get this info and insight is to have a friend film a few takeoffs—then view them in detail. The next best approach is to have an experienced pilot watch us closely. He or she should be looking at our hands (position and action) and our keel position (relating to wing attitude). With a few observed takeoffs, these experienced pilots should be able to let us know our habits and performance. If our methods are less than stellar perfect, we must change them.

The best way to effect a cure is to go to the landing field. Running on the flat ground will teach you all you need to know about proper control and will help you change technique in a comfortable manner. Plus, you will be able to do many more trials than you would have if you’d climbed a training hill. To try the slipping-hands-down trick, it helps to have about 10 mph wind. All other matters can be practiced in lesser wind.

Again, we caution that at least 80% of us have faulty launches and only 10% have consistently perfect launches. Where do you stand? If you have any remaining doubts, just sign up for the TTT Team Challenge next year, and we will be sure to display and analyze your launches in our launch seminar.

COPYRIGHT © 2008 by Dennis Pagen


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