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The Nose High Launch

Copyright © 2005 Don Burns

There is little more sacred to the hang-glider pilot than launch technique. While there are many varied techniques and preferences for various aspects of launching, nearly all pilots can chant in unison the commonly accepted mantra, "hold the nose low and run hard!". "Nose low, run hard" launches, have been the accpted technique since the days of the standard rogallo and continue to be the most undisputed advice for good launches. Well, this article is about to preach heresy.

Why? Because we want to stir up contraversy for the fun of it? No, but because this accepted method of launching overlooks some of the most important ingredients for successful launches and safe flying, and exists because of some mythical premises. Even if the hair on the back of your neck is standing up in reaction to the claim that it is ok to hold your nose high on launch, or it is less acceptable to run with your nose low, read on for some good analytical discussion.

Successful Launches

Before we can effectively define what does and doesn't make a successful launch, perhaps we should define what a successful launch is. The popular method for judging a launch, in fact, is often to measure it against the two elements "Nose Low", "Run Hard". Seldom are hang-glider pilots heard commenting on a) the level of pitch and roll control during a launch, or b) the transition from running to flying, or c) the change in angle of attack during launch.

Yet, if we were to point these qualities out, few would argue with a) the pilot should be in full control during the take-off run and b) the glider should be loaded gradually and smoothly during the take-off run and c) the angle of attack should change very little during the take-off run. But are these qualities really considered when judging a launch?

As a hang-gliding instructor of over 25 years, allow me to share a method of observation of foot launches that you may not have considered before. One of the key skills a hang glider instructor must possess is the ability to observe and analyze student flights. Hang gliders conform to the laws of physics 100% of the time, and behave according to some very simple principles. Often subtle changes in angle of attack or bank angle are difficult to see when focused on the student's hand or body position, and the visual scope only includes the control bar. Watching the entire glider causes these subtle changes to be more easily discernible.

Next time you find yourself observing launches, position yourself so that you can watch from behind the launching pilot, and focus on the top center of the glider, at the kingpost, or where the kingpost would be on a topless glider. Note the change in angle of attack during launch, as well as subtle changes in direction and bank that may occur during launch. Without looking at how crouched over or powerful the pilots strides are on launch, ask yourself, how in-control is this pilot really?

What is "Nose High"?

When observing launches, note what seems to be the accepted angle of attack for a "good" launch. Typically, this is quite nose-low. Speaking in terms that we can quantify, the accepted angle of attack for any given launch is often close to level with respect to the horizon. If you haven't noticed this, notice it now. In fact, the next time you pick your glider up to launch, notice the angle of attack with respect to the horizon when you feel most comfortable to start your take-off run.

Compare this to what the angle of attack the glider has while in flight. In most cases it will be significantly lower. In fact, if you maintained the angle of attack, with respect to the horizon in flight, you'd find youself flying at very high speeds. Even on beginner gliders, this speed is significantly above what most humans can run at.

So, if you hold the angle of attack at something the glider will seek when it is flying 40 mph, do you intend to launch at that speed? Of course not! SO, what has to happen then for you to be able to launch at running speeds? Right, the nose has to come up during the launch run. In fact, this is what you will observe for 100% of nose low launches. To this day, I have not met an individual who can run 40 mph for launch.

You may have guessed by now that I am a propnent of the "nose high" launch. What do I mean by "nose high"? I approach most of my launches, by holding my nose at an angle of attack (it will be an angle of attack when I start to run, anyway) that will match my launch speed. Nearly all "advanced" pilots I have run across believe I am launching with my nose too high. If they don't know me, they will offer their knowledgable assistance and ask me to lower my nose, or I will stall on launch. Ah... enter Myth #1.

Will starting your launch with your nose "high" cause you to stall?

It is, indeed, the popular belief that starting your take-off run with your nose high, will inevitably result in a stalled launch. This is untrue. It is true, of course, that you will stall your launch if you push the control bar during the take-off run. But this is different than starting with your nose high and allowing the glider to seek its own angle of attack during the take-off run.

Pat Denevan, a world renowned and well respected hang-gliding instructor, teaches a launch method to both beginning students and advanced pilots taking his "Launch and Landing clinic" which includes a crucial component: Tow the glider with the harness straps. In fact, if a pilot is able to tow the glider with the harness straps and completely let go of the control bar, the glider will seek the perfect take-off angle of attack with no input from the pilot. This is easily demonstratable.

In fact, I often do a demonstration for disbelievers in the "nose high" approach, as proof-positive that a successful launch can be accomplished with the nose quite high. I approach the launch as I normally would, with the flying angle of attack set to launching speed, then ask, "Is my nose too high?". Most of the observers, used to a nose-very-low launch will nod their heads. Of course, this prompts me to raise the nose higher. "How about now?" I'll ask. I'll repeat this until my keel is on the ground and the basetube is sitting directly in front of my eyes.

At this point, I'll lean forward and start to run with my hands by my side, not touching the control bar. The glider will lift off the ground, the nose will lower until the right angle of attack is attained, and I'll fly off the hill with an adequate amount of flying speed.

Why does this work? Because I'm towing the glider with my harness straps for the entire take-off run. Skeptics say this works because I am a talented pilot who has been flying hang gliders for most of my life. However, I only simply run in a straight line to take off. How much talent could there be in running in a straight line?

If you think about this long enough, you'll realize that this is exactly how paragliders take off. Imagine telling a paraglider pilot that he should hold his glider's nose low before taking off!

No, launching with your nose high will not result in a stall. Its a myth!

What's best?

A quick, multiple answer quiz, then:

  • The best method for launching a hang-glider is to:
    1. hold the glider's angle of attack low and run hard, allowing the nose to rotate up during the run.
    2. hold the glider's angle of attack at the proper angle of attack for take off speed and do not alter the angle of attack during the take off run.
    3. hold the glider's angle of attack higher than the proper angle of attack for take-off speed and allow the nose to come down during the take-off run.
  • On question #1, if it is not possible to get the angle of attack exactly right, it is better to
    1. err on the side of having the nose too low.
    2. err on the side of having the nose too high.

I'm quite certain that the majority of readers would agree that the answer to #1 is b. It just seems logical that having a constant angle of attack during the take-off run is the correct approach. Again, though, the take-off angle of attack is usually higher than most expect.

But what about question #2? Conventional wisdom would take the "conservative" approach and dictate a as the correct answer, since it adheres closer to our age old "nose low, run hard" take off technique. However, there are actually advantages to having the nose high and detriments to launching with the nose low. In fact, it takes a higher level of skill to launch with the nose low, than it does to launch with the nose a little higher than take-off speed angle of attack.

Let's analyze this carefully. At the begining of this article, we just three important ingredients to producing a good launch:

  • Pitch and roll control authority during the take-off run.
  • Smooth transition from running to flying.
  • Little to no change in angle of attack during launch.

Pitch and Roll Control Authority During the Take-Off Run

Hang-gliders are weight shift control aircraft. Even rigid wings like Atos' style gliders use weight for pitch control. For the glider to be controllable under weight shift, if must be carrying at least part of the pilot's weight. If it is not carrying the pilot's weight it is very difficult to control.

Prove this to yourself by practicing a ground run with your glider on a flat or lightly sloped field. Do not hook in, but rather, run with the glider, holding the nose low with your arms wrapped around the downtubes. Have a friend run along side and momentarily pull down a side wire. Experience, then, first-hand how much effort it takes to correct that disruption in the take-off run. This is no different than what would occur if a thermal got under that opposite wing during the first moments of take-off run.

A pilot's harness straps must go tight at some point in the take-off run. The moment this occurs, control of the glider shifts from brute force to weight shift. When you hold the nose of your glider down during the take-off run, you postpone the moment when your straps go tight. Until your straps go tight, you do not have weight shift control over the glider.

Everyone should agree on the fact that a hang-glider must accelerate forward during launch, going from a speed below what is adequate for flying to or beyond a speed that is adequate for flying. The right way to accomplish this acceleration is to do so by shifting one's weight forward, relative to the CG of the glider. This is what occurs when one "tows" the glider with one's harness straps. But this cannot occur until the straps are tight. Nose high launches ensure that that the harness straps are tight as early as possible. Once the harness straps are tight, by all means, pull in to accelerate the glider.

Note also that, not only can the glider be accelerated by shifting the weight forward, but it can also be controlled laterally because it is carrying weight, which can be shifted to compensate for changes in roll during launch. Contrarily, if the nose is being held down, and a thermal gets under one wing, the glider must first lift high enough to allow the harness straps to go tight before weight shift correction can occur. During the time it takes for the glider to lift high enough to tighten the straps, precious milliseconds have been lost in lack of control.

Allowing the nose to begin at a raised angle of attack, ensures that the harness straps go tight early in the take off run and provides the launching pilot with weight shift control for the largest percentage of time in the take-off run.

Smooth Transition to Flying

The speed at which a hang-glider stalls goes up with increase in weight it is carrying. So, while standing on launch, preparing to run, the glider has the ability to carry as much weight as is comensurate with the wind (its current airspeed). As you add speed in the take-off run, the glider gains ability to carry more weight. Ideally, if we were to graph a glider's stall speed, relative to the weight it carrying at any moment during the take-off run, we would hope to see the airspeed at some margin greater than its stall speed.

Now, the term "smooth transition to flying" is a phrase that is taken directly from the FAR Part 103, Pilot Proficiency standards, for a beginner rating. It reads:

    D. Launch unassisted showing:
    1. Agressive run, if foot launched.
    2. Good angle of attack and pitch control.
    3. Directional control.
    4. Smooth transition to flying, during launch.

Most pilots I have interviewed who are firm believers in the nose low launch describe their take-offs like this:

    "I hold my nose down so I can run hard and get up enough airspeed before leaving the ground."

What have they just described? The nose goes down, the run takes place, holding the nose down, when some speed is achieved, then something happens and we are in the air. What is that something that has happened to get us into the air. If you've taken the time to observe launches, you'll realize that that something hapening is the nose coming up. Analyze then, what is happening with regard to the relationship between stall speed, glider airspeed, and glider loading. If the nose is low during acceleration, the glider is carying little of the pilot's weight, or it is carrying the pilot' weight on the downtubes where he his holding the glider. Then, quite abruptly, the weight is transferred from the pilot's legs, to the glider. This abrupt change, is _not_ a smooth transition. It is, in fact, an abrupt transition. This is undesirable. Enter myth #2.

Myth #2 is the interpretation of feeling that pilots get when being "tugged" by the harness straps, that this is holding the pilot back from accelerating forward in launch. When the nose is high and after a step or two, the "tug" on the harness is interpreted as holding you back. The myth is that the glider can, somehow, not be accelerated when this "tug" is occuring. This is not true.

In fact, the difference between holding the nose low and using your legs and a brute force grip on the control bar, to accelerate the glider forward, is far more difficult than making use of gravity to accelerate the glider forward. When a pilot is launching down a hill, each step is at a lower elevation than the step before it. With each step, the nose-high pilot is placing more weight on the glider. If the pilot is towing the glider, the natural reaction will be for the glider to accelerate forward.

Personal opinion here, now. Item one on the Part 104 Pilot Proficiency for demonstration of launches "Aggressive run, if foot launched", is perhaps poorly worded. Perhaps, "confident run", or "assertive run", might be more appropritate. A properly executed launch, using gravity to accelerate the glider can produce a perfectly clean and fast launch without agressiveness. In fact, under some circumstances, one can turn a lumbering stride into long steps while pulling in and have a take-off run that is more than adequate, with plenty of speed building up due to pulling-in, towing with the straps and gradual build-up of load on the glider. That is a smooth transition.

I have seen many cases of interpretation of "aggressive run" as short, fast, choppy and sometimes violent steps during take-off. This is very detrimental to doing a good launch, because the focus is on the run, and not on the acceleration of the glider. One does not necesarily result in the other.

Little to no change in angle of attack during launch.

From our quiz above, the ideal launch is one where the angle of attack is set for adequate take