Becoming Biwingual

So here you are, capable of driving around at 40 mph in your hang glider. Carving turns and shooting long flat tough approaches and sensing when it's just the right time for that elusive landing flare. You are thinking that learning to fly a paraglider will be easy as compared to learning to hang glide.

Well... mostly correct.

It is true that the paraglider appears to be simple craft with an almost 1 dimensional set of controls but it is a Dr Jeckyl/Mr Hyde form of flying machine. Kept in very simple sled conditions and flown with molasses movements of the brakes it is truly a magically simple and easily flown aircraft. Get either extreme or abrupt in the brake application or try to fly in gusty conditions and it not only becomes about the hardest of aircraft to fly, it can become sport death.

You will have to put in the usual 20 hours of ground handling practice so as not to look like a total geek in the launch area. Your instructor will show you some of the 500 or so tricks to mastering the art of ground handling. You might even invent a few tricks of your own. If you think of ground handling as kind of like learning to juggle then you will be on the right track. Think of the inflation as the "set up" of your wing. Then follows kiting the wing overhead for a few seconds while you do the "preflight". In no wind you will be preflighting while taxiing (running). Soon after or maybe even minutes later comes the "launch". To inflate on a steep hill where you are immediately committed to launching would be the same as asking a stranger to set up your hang glider then launching it without doing a preflight. This means that well rounded launch areas that allow a shallow upper area to inflate in with no chance of getting launched and then a steeper area to launch in is ideal. Sharp edged cliff launches really do suck. I remember asking Matt Taber at Lookout Mt GA if I could fly my paraglider there during a roadtrip in '93. I understand he usually says NO but knowing my cautious nature and perhaps to humor me, he said "OK" with a grin. After walking about 1/2 mile back and forth along the ridge top near the famous lookout launch ramp I returned and told Matt that there aren't any safe launch areas for paragliders and I would have to hang glide. He said "I could have told you that." (still grinning) We both appreciated each others decisions that day.

A delightful surprise awaits you. My first flight in a paraglider was the 200' training hill in Santa Barbara. As soon I was about 50' agl I pulled a brake about 1/2 way down to initiate a turn. After the turn got started I went to trim (hands up) to allow the wing to remain at that bank angle like I was in a HANG GLIDER. As soon as I raised the brake, the wing leveled off. "Hmmm... I get it!" I thought to myself, "You gotta hold the brake down to continue turning." Just like driving a car with your hands on the wheel in the 9 and 3 o'clock positions. Lower one hand a bit and raise the other the same amount and voila... you're turning. Equal hand heights and you go straight. This makes first tries at heading control a snap.

The approach is likely going to mean instant success for you, although you might undershoot your first few times when the wind picks up above 8 mph. An 8 mph headwind can reduce your glide to a dismal 3:1. This means even more than you are used to... get to your landing area with plenty of height. Stay close to your target. Fig 8 approaches actually work much better than in hang gliders especially when the wind is above 5 mph. The flare is going to be fun compared to your attention level necessary when flaring your hang glider. No more long glides near the ground. Your instructor will demonstrate a couple of landings for you and you will probably take to it like a duck to water.

The paraglider becomes vastly more complex when you add in the pendulation. Imagine that you are in your car and you hang a small weight on a 12" string from your rearview mirror. Whenever you accelerate or touch the brakes or make a turn, the weight gets to swinging. This weight represents YOU hanging under your wing. Every brake change or bit of turbulence changes the direction or speed of the wing and your momentum causes you to pendulate. This pendulation can be both in pitch and roll.

It is easy to do exactly the wrong thing in dealing with pendulums in roll... especially if you are a hang glider pilot. Yes, as a HG pilot you are at a DISADVANTAGE over the average non pilot in this regard. Imagine you are launching your hang glider and during the run you drop one wing. You are accustomed to running straight down the hill and steering full opposite roll until you feel the wing is just about level then return to center. In a paraglider this course of action can be very exciting to say the least.

Now let's try launching a paraglider. Pretend you are running and about 1 second from launching and your paraglider is 20 degrees banked (rolled) to the right side. Your reaction might be to run straight ahead and steer strongly to the left. Now it's 1 second later. You just launched and the wing is still banked to the right with you steering left. Just like pulling a pendulum to one side and letting it go, the natural pendulum stability of you under the wing will cause you to pendulate from the 20 degree right bank to about a 10 degree left but since you are steering hard left the wing actually goes to a 25 degree left bank angle. About 2 to 3 seconds after you lift off you see with shock that you are now banked hard to the left and you steer hard right. Now the wing is rolling hard right both from the natural pendulum stability and from your right braking. You are passing left under the wing as the wing is going to the right above you. Back and forth you chase it trying to stop the roll. If it's a 50' hill you will probably do about 3 reversing swings and slam into the ground quite banked. Ouch... PLF.

The correct way to deal with launching the paraglider is to steer gently to make the wing go where you want it to go and always run to STAY UNDER YOUR WING. Running first to your desired direction will instantly bank the wing away from the change of course leaving you either launching in a large roll pendulum or having the wing fall to the ground. So the bottom line here is... the reactions for launch roll control in a hang glider are WRONG for a paraglider.

IN FLIGHT roll pendulums can lead to problems especially for the hang glider pilot too. Try to follow this calamity. If you are flying straight and level and abruptly lower a brake to a position that equates to a 20 degree bank, the reaction of the wing is to perhaps roll initially to about 30 degrees then return to about 15 degrees then up to 22 degrees then eventually dampening to a 20 degree bank angle. The unfortunate scenario that has repeated itself with many students comes the first time they summon the courage to do a quick 360 close to the hill. Perhaps they have done many 360's already, but since they need to complete the 360 quickly (because of being near the hill) they start the turn very abruptly with a deeper application of the brake than usual. For about 3 to 4 seconds the wing rolls into a beautiful 40 degree bank turning very quickly. You are thinking that life is great! After carving a 180 degree turn the wing does it's natural pendulation, rolling almost level (to about a 10 degree bank angle) leaving the pilot flying almost straight at the hill. As a hang glider pilot what do you do if your wing isn't rolling from your input? Well if some isn't enough then do more. In the paraglider, adding more brake could cause the inside wing to reverse flight direction (see "Stalls" below) putting you into a negative spin. If you were to KEEP the brake position you started with, the wing would likely do it's 2 to 3 seconds of 10 degree bank then pendulate again to a 30 to 40 degree bank angle. If this isn't soon enough to keep from hitting the hill then you had better be good at PLF's.

The natural pendulum period of a paraglider is about 5 seconds for a complete pendulum cycle. (fore and aft or side to side) You will eventually learn to anticipate these swings and perhaps use them to your advantage. Remember the abrupt 20 degree bank that went initially to 30 degrees as described at the start of the paragraph above? Well let's pretend that you really DID want a 30 degree bank angle. By initiating abruptly to the 20 degree brake position, then (just when it goes to 30 degrees) you add the extra little bit to keep it at 30 you will have managed to roll from level to a 30 degree bank with little or no pendulums. Very cool! Now you are getting into the swing of things.

This is about the biggest can of worms that paragliding has to offer. It can lead to blown takeoffs, hard landings and the all too feared wing collapse.

Unlike roll pendulums where it is probably best to let them dampen out for the most part, the pitch pendulum needs to be constantly monitored and controlled. Like a hang glider doing a series of stalls and recoveries, the paraglider will do a similar series of little dives and pullups as the wing pendulates in pitch. Proper braking action will help dampen these pendulums. Obviously as the wing goes behind you, let up on the brakes and when it goes in front of you, add brakes. This is where your experience as a hang glider pilot is a DISADVANTAGE. If you are upright in your hang glider with your hands on the downtubes and you get gusted pointing your nose to the sky, you are trained to pull in (down) on the downtubes to get the nose back down. If you do this to the brakes in the paraglider you will be doing exactly the wrong thing.

Your angle of attack is changing as you pendulate. This leads to a very BIG issue. The paraglider has a unique characteristic that is so different from other aircraft that it makes a hang glider closer to a CESSNA than it is to a paraglider. You have no doubt heard of the COLLAPSE. There have been many articles written about it's causes etc. Mostly these have talked about pressure inside the wing. This description of collapses is TOTALLY WRONG. It may be true that there is some amount of internal wing pressure, (which helps to keep the fullness and efficiency of the airfoil) but the wing stays away from you and fully open (spanwise) causing the lines to remain straight and under tension because of the aerodynamic force. The force is a result of airspeed and ANGLE OF ATTACK. If you reduce the angle of attack, the force reduces and changes it's direction. Reduced enough and the force reduces and changes it's direction such that the lift component becomes negative. At this point, the lines go slack because strings can't push they can only pull and the wing collapses (folds downward). Usually most of the wing remains at a positive lift angle of attack while only a section of one tip reduces to the folding angle of attack. This is the assymentric collapse we have so often heard about.

To reiterate, maintaining a POSITIVE ANGLE OF ATTACK is what keeps the wing inflated overhead. "Pulling the brakes to pressurize the wing" is an abbreviated and misleading way to say that by flying slower you have a steeper glide ratio and a higher relative angle of attack making you less likely to reduce any part of your wing to the zero lift angle of attack thus reducing the chances of a wing fold (collapse). If someone tries to tell you that by keeping pressure inside the wing you prevent collapses then consider their misunderstanding as proof that the term "pressurize" is misleading. With this concept understood it is easy to see that by applying your speed bar (lowering the leading edge) you raise the likelyhood of a collapse and also that in normal circling it is the outer wing that is more likely to collapse. Think... angle of attack.

Take the knowledge you have now about angle of attack and collapses and you will easily figure out that a safe paraglider launch is to ride the brakes quite deeply during the taxiing and takeoff run. Almost to the point of stalling. Then as you start to lift off, gradually raise the brakes to a midspeed level. It also should be obvious that you should start your takeoff run gradually so as not to run too far ahead of your wing causing a pitch pendulum. Your instructor will help you work on the art of launching.

One final word on folds (collapses). Paragliders are usually close to twice the wing area of a hang glider so it's no big deal to get a 50% assymetric fold. Just add a LITTLE opposite brake to maintain your heading and you'll be gliding about like a skydiving rig.

Briefly, unlike a hang glider that does a normal stall recovery by lowering it's nose all by itself, a paraglider when flown slow enough will actually very suddenly reverse flying direction leaving you in a freefall on your back. It is the strong pendulum stability that keeps the wing from nosing down when you are approaching the onset of this "full stall". Therefore, there is no advanced warning of the "full stall". If you are turning (with deep brakes) and only the inside wing enters this reversing direction mode, you can turn your wing into the equivalent of an autorotating helicopter blade. This is known as a "negative spin". Your instructor should help you learn where too deep in the brakes is. Pay attention. Middle brakes is safest, high brakes can cause folds and deep brakes can truly become a living nightmare.

As stated above, the paraglider can be an utterly fantastic flying machine. Be careful of extremes or abrupt control movements. Keep it in relatively smooth air and you are likely to really enjoy this slow speed brother to hang gliding.