Equipment and Accessories

The Launch - Technique - Emergency situations

Equipment and Accessories
Releases:

There are numerous ways to set up releases when aerotowing, but we’ve come up with only two methods, which aren’t inherently problematic.

The first method, is the use of two releases, a primary and a backup. The primary release is actually attached to the keel and has a long cord or cable, which runs down to a loop or handle at the bottom of the down tube or one side of the base tube. The backup release is the same release used in the “single release” method explained below-a simple, reliable release attached to the shoulders of the harness. A long bridle (about 8 – 10 feet long) is attached to the primary release with a weak link (more on this later), and passes through the tow ring on the towline and then to the backup release.

The second method is the use of a single release (something simple like a reliable two string release), which is attached to the shoulders of the harness. The advantage of this method is the simplicity of having just one reliable release that, by not having to incorporate a bridle, eliminates the possibility of the bridle hanging up on the tow ring. The main disadvantage, and the reason this method is rarely used today, is the high amount of pulling in required to keep the glider down in position behind the tug. The use of a single release is definitely not recommended when flying a glider with heavy pitch pressure.

It’s important to note that the position on the keel where the primary release is attached has a large effect on the trim of the glider during tow. If it is positioned too far forward on the keel, you’ll find yourself having to push out the entire tow to stay in the proper position behind the tug. If the release is positioned too far back, you’ll have to pull in a lot. If positioned perfectly, you should be able to tow almost hands off. All gliders vary in the proper position, but usually the position will be at least 4-6 inches in front of main hang point, and sometimes (such as with a Falcon) as much as 2-3 feet in front of the main hang point. The primary release should definitely be securely attached. A good method is to tie a strong line off behind the king post and then run it forward and wrap it around the keel and tie it off again at the appropriate position.

It’s also important to note that when attaching the primary release to the downtube, enough slack should be left in the cable housing so that the release is pulled tight by the towline. The housing stays loose. If the housing should ever pull tight, it may cause the release to inadvertently open. There are a variety of safe, high-quality primary and backup releases on the market, but we’ve come to the conclusion that, when using the two-release method, the release, which is attached to the keel, should be the PRIMARY release – the first release used. The shoulder release should only be used as a backup. The reason for this is that sooner or later, the long bridle may wrap around and snag on the tow ring. If you had used the upper release when this happens, you’ll find yourself suddenly being towed solely from the shoulder release, and this is no big deal. Like explained above, being towed by the shoulders is a standard method. Pitch pressure will suddenly increase and it will be necessary to pull in quite a bit more, but the situation will remain controllable and now you can simply use the shoulder release to get off the towline. If, however, you had used the shoulder release first, and the bridle snags on the towline, you will suddenly find yourself being towed by the upper release, and this IS a big deal. This is likely to cause the nose of the glider to pitch down violently, and common sense tells us that this is not such a good thing.

Weak Link:

The strength of the weak link is crucial to a safe tow. It should be weak enough so that it will break before the pressure of the towline reaches a level that compromises the handling of the glider but strong enough so that it doesn’t break every time you fly into a bit of rough air. A good rule of thumb for the optimum strength is one G, or in other words, equal to the total wing loading of the glider. We use 130 lb. Braided Dacron line, so that one loop (which is the equivalent to two strands) is about 260 lb. Strong, about the average wing loading of a single pilot on a typical glider. For tandems, we use two loops (four strands) to compensate for nearly twice the wing loading. When tying the weak link, It’s a good idea to wrap it four or five times around the loop in the bridle before tying the knot. This way, the knot can be hidden within the extra wraps and excluded altogether from the equation. *REMEMBER – it should never be assumed that the weak link will break in a lockout. Always hit the release before there is a problem.

Carts (dollies):

The features of a good launch cart include the following:

The front two wheels are pneumatic, castering and a sufficient diameter to provide for the given terrain

The basetube mount is adjustable enough to account for different gliders and is open enough so that there is no chance the wheels on a glider can become wedged to the cart

There is some way to hold onto the cart during the rollout (loops or a string running the length of the basetube)

The keel mount can be adjusted to set the proper angle of attack on the glider

The angle of attack should be set in about the same position as minimum sink or stall would be in normal flight. As explained in Dennis Pagen’s “Towing Aloft”, when hanging freely from the glider in the cart, the basetube should be even with the pilot’s forehead. It’s better to have the angle set too high rather than too low. If the angle is too low, the glider won’t leave the cart or may even want to dive in. Too high, and the glider is more likely to leave the cart in an unleveled attitude.

The Towline:

The towline is attached to a release on the tug (so that the pilot of the tug can release the glider at any time) and is fitted with a tow ring on the glider’s end. It is better if the tow ring is not perfectly circular, as the long bridle used in the two-release method is more likely to wrap around it and snag. A teardrop shaped tow ring can greatly reduce the chance of this happening.

Different length towlines can be used, but generally, the towline should be between 150 and 300 feet long. A short towline is generally better when tight turning is required on tow. The glider also responds quicker relative to the tug, though the cone of workable positions behind the tug is smaller and reaching the point of lockout is slightly easier. A long towline allows the pilot to get further out of position without locking out, though in vertically unstable conditions, it can be more difficult to stay in proper position.

The Launch

Hang Check:

Angle of the glider on the cart (pilot’s forehead even with basetube) Standard hang check

-Main and backup hang loops

-Carabineer locker

-Harness lines clean

-Leg loops

· Top release (if using one)

-Fully closed

-Slack in cable housing

· Weak link

-Proper strength

-In good condition (not frayed)

· Bottom release

-Fully closed

· Basetube is clear (VG cord is stowed, wheels are free)

· Wheels of cart are straight

· Towline runs straight to tug (not wrapped around tail of tug)

Rolling Out:

Make sure the wheels of the cart are straight so the cart doesn’t veer. Get a secure grip of the handles or rope on the cart. Keep your arms rigid just when the cart begins to roll and then relax (the force of the towline can pull you forward too far and possibly nose the glider in). Focus on the tug. When you feel the glider just begin to pick up the cart, drop the cart. Maintain your altitude at about 10 – 15 feet by pulling in, and wait for the tug .Be prepared to let out on the bar the moment the tug’s wheels leave the ground .Follow the tug (maintain an attitude so that some part of the tug is on the horizon)

Special Situations:

Cart veers

If the cart does begin to veer for whatever reason, DON’T hold weight shift to try to straighten the heading. This won’t change the track of the cart one bit, but it could very easily cause the glider to launch in a turn. Instead, use a bump-shift method to shift the cart. Lead with your body the way you want the cart to go and then jerk the basetube to pull the cart with you. It’s not a big deal to launch with the cart veered a bit to one side, but it can be a big deal to launch without a wings level.

Propwash.

When flying with an especially high wing loading (like tandem) or using a short rope, you may hit the tug’s propwash on launch. You’ll generally punch right through it with very little effect on your heading. Don’t overreact but be prepared to make a correction if necessary. Weak link breaks. This is one real good reason to launch with a little extra speed. If the weak link breaks right off launch, pull in immediately to avoid a stall but be prepared to flare hard to avoid diving right into the ground. If things get a little hectic, staying prone and rolling in on the wheels is an option.

Turbulence or Crosswind.

Stay on the cart a bit longer in these conditions so that you’ll have good maneuverable speed the moment you lift off. You may need it. Don’t come off too soon. If you push out to try to lift off quickly, the glider may easily drop a tip or mush back into the ground.

Technique

Positioning:

The general rule of thumb is to keep some part of the tug on the horizon. Try to keep the wings on the horizon – this puts the glider slightly higher than the tug and gives you a slight head start when the tug hits lift. If the tug hits sink and/or suddenly drops, It’s easy enough to pull in and quickly get down with little risk of breaking the weak, but if the tug suddenly climbs, there is only so much or so fast you can push out without losing maneuverability or breaking the weak link. This is why it’s usually good to err on the side of being slightly higher than the tug, especially on launch.

Too high

If you get a lot higher than the tug, you’ll be pulling the tail of the tug up and causing it to dive. This is about the scariest thing you can do to a tug pilot on launch, for it’s possible to pull him right back into the ground. If this happens, you’ll almost certainly “get the rope”. Remember: Err on the side of high, but don’t overdo it.

Too low

If you find yourself low on launch, the tug can leave you in the dust, or more specifically, in the propwash. In this situation, if you find yourself having to push out severely, it’s better just to release from the line, land, and try it again. When you’re close to the ground, you don’t want to risk breaking the weak link, or worse, losing control and locking out. If you’re at altitude and you find yourself low, not to worry. Just stay on the line and gently push out, and you’ll eventually climb back up to the tug. An abrupt pushout is a good way to snap the weak link.

Banked away from the tug.

This is the most critical thing to stay on top of , for if not corrected, it can rapidly become a lockout. There is a fairly large window (a cone) of workable tug position, but once you’ve exceeded this boundary, the pressure to sling you away from the tug can become overwhelming. This is what is known as a lockout, and you want to release before you feel this pressure begin to build, especially when at a low altitude. Always correct for roll first and adjust your height second. For example, if you find yourself low and banked away from the tug, get your wings level and pointed at the tug first, and push out to climb back up on the tug.

Handling the Glider (avoid oscillations):

Proper Form:

Aerotowing can be very conducive to oscillations, but it’s a fairly simple matter to learn how to avoid them. Staying relaxed and having good form become very important. Since being on the towline gives you a lot more leverage by which to control the hang glider, it becomes very easy to yaw the glider. If, for example, you pull your shoulders to the right, you’re really yawing the glider to the left, most likely the opposite direction from where you want to go.

The solution to this problem is actually real simple. Don’t lead with your shoulders. Lead with your hips and legs. There are several ways to look at this, though they all say the same thing:

Pull your hips to the wing

Pull the wing to your hips

Steer the glider like a bicycle or a shopping cart

You’ll find if you’re using correct form, your head and shoulders will remain centered in the control frame, even though the towline may be attempting to pull them to one side or the other. If you continue to lead with your shoulders, the glider will oscillate.

Making correction:

You’ll find you generally have a lot of authority (when using proper form) to bank and/or level the wings on tow. This is because you’re flying fairly fast on tow (usually 30 mph or more). Therefore, it is rarely necessary to pull in when making a correction. Of course, if a thermal got one wing and you need that extra bit of authority, pulling in can help. Because of this extra authority, it is easy to over control. The following outlines a good technique to make a correction without over controlling:

Maintain a constant roll command (remember – hips not shoulders). DON’T use the bump method.

As soon as you see that your command is working, and the tug is coming back into the proper position in front of you, relax and center up.

Now that the situation is back under control, you can gently bring the glider back into perfect position behind the tug if it isn’t already there.

If you continue to hold the roll command until the tug is in proper position in front of you, the glider will control to roll past it and you will find yourself heading away from the tug in the other direction. This is an oscillation caused by over controlling (different than the oscillations caused by leading with your shoulders). The key is to only make a correction if you’re heading of course. Otherwise, just relax and let the glider fly.

Turning on Tow:

When the tug makes a turn on tow, you want to follow the same path through the air that the tug makes. This requires that, once the tug turns, you wait several seconds before you make the same turn. A real good cue to know when to start your turn is to wait until the towline begins to pull the nose of your glider in the direction of the tug. At this point, you do whatever is necessary to follow the tug’s path. You’ll find that very little input is actually needed.

Too far inside. If you begin your turn too soon after the tug begins its turn or if you bank too steeply when you do follow it’s turn, you will find yourself on the inside. This will cause you to slow down and get low. If this happens, just coax the glider back into the tug’s flight path. If you correct too quickly, or you may find yourself overshooting and possibly locking out to the outside of the turn.

Too far outside. If you begin your turn too late or if you don’t bank enough, you will find yourself on the outside of the turn. This will cause you to speed up and get high on the tug. It is very easy in this situation to “get slung off” to the outside – a lockout.

If you have to err on one side or the other, it is better to err on the inside – especially when at a low altitude. This way, you’re not in as much danger of locking out. Keep in mind, though, that if you’re too far on the inside, you will get low and slow – control will become sluggish and you may stall.

Emergency Situations:

Weak link Break (or premature release):

Always be prepared for a premature release from the towline. Pull in immediately to prevent a stall and, if you’re low, focus on pulling off a good landing.

If you release right off of launch, just continue to fly straight ahead and roll in on the wheels if there’s no time to get upright.

If you’re launching from a short field, and you release too late to continue to fly straight without coming to the end of the field but too low to pull off and approach and come around into the wind, you’ll either have to turn 90 degrees and land cross wind or turn 180 degrees and land downwind. Again, landing on the wheels may be a good option.

You have the towline:

If the tug pilot released you and gave you the towline or if the towline simply broke, hit your own release and get rid of it. If you’re high when this happens, try to drop the line over the field. Otherwise, just getting rid of it is the most important thing. Let your imagination toy with the idea of landing with 250 feet of rope running over your basetube, and the reasoning becomes clear.

Release failure:
The thing to do in this case is to follow common sense. If you are using two releases, hit your second release. If this fails, now would be a good time to test out that hook knife. Remember not to panic – if the tug pilot is doing his job, his eyes are going to be on you, and he has a release on this end.

Lockout:

A lockout happens when you reach the boundary of that cone of workable positions behind the tug. It can happen real abruptly if you are banked steeply away from the tug, especially if you are on the outside of a turn, or it can happen slowly if you are gradually banking away from the tug. In either case, the important thing is to have the awareness of how far you can go before you can’t get it back. In a gradual lockout situation, you can feel the pressure required to roll back becoming stronger and stronger until you can no longer fight it. You should release before it ever gets to this point. If this happens low, you don’t even want to take a chance. If you find yourself banked away from the tug and you can’t immediately get it back, hit the release. Don’t ever count on the weak link to break or the tug pilot to hit his release.