Another Look at No-Wind LandingsBy Scott Miller on 2007-10-16
The advice Brian Germain provides in his article titled "Surviving the No Wind Landing" might help you achieve consistent, comfortable landings on days when the winds are calm. Unfortunately, other jumpers might not be as successful when trying to follow that same advice.
Some of the techniques described in "Surviving the No Wind Landing" are slightly advanced, and jumpers who are just trying to perfect basic flaring skills might find those techniques difficult to use. Other information in that article might be helpful to people flying certain specific sizes and types of canopies, but we might discover that this information does not actually apply to a significant number of canopies in common use.
The first piece of advice Brian offers is to "make sure you level off within touching distance from the ground." This can certainly lead to softer landings, particularly in calm winds. There is only one problem: if many jumpers fear no-wind landings, there are probably even more who are afraid of flaring too high. For some people the game is over at the instant they realize they have made that mistake: they expect the worst, stop flying, and start panicking.
In an effort to always level off within touching distance from the ground some jumpers develop a habit of consistently flaring too low. Another common problem occurs when people reach for the ground with their feet, believing they are within touching distance when they are actually a few feet high. People who suffer from these habits are often pleasantly surprised, and see a remarkable improvement in their landings, when they learn that it is not actually necessary to level off with your feet right at ground level. Many modern canopies are actually very forgiving of a high flare.
Understanding the Stall
A very common concern is that a canopy will stall if it is flared too high. Brian reinforces this concern when he mentions the importance of arriving at the ground "before the stall breaks." To understand why flaring slightly high is not necessarily a problem we need to take a closer look at the concept of a stall.
"Stall" has a very specific meaning in aviation. It is a significant decrease in lift caused by a separation of airflow that occurs when a wing reaches its critical angle of attack. Understand? No? Okay, then imagine a car driving down the highway, heading toward a curve in the road. Most highways have gentle curves, for good reason, because cars tend to fly off the road if a curve is too sharp.
Now think about the relative wind blowing in your face under canopy. Your canopy bends that relative wind to create lift. Pulling down on both toggles pulls the tail of the canopy down and bends the relative wind even more, creating even more lift. The further you pull the toggles down the more lift is created, up to a certain point.
The "critical angle of attack" is the point where the curve becomes too sharp and the relative wind separates from the canopy like a car flying off of the road. This separation results in a sudden and dramatic loss of lift. The term "stall" refers specifically to the sudden loss of lift that occurs in this particular situation.
Image 1 shows a canopy being intentionally stalled. In frame "A" the brave and handsome test jumper is putting the canopy into brakes, pulling the tail down and increasing the curve that the relative wind must follow. In frame "B" we see the canopy in very deep brakes, but not yet in a stall. The canopy is curving the relative wind sharply and creating a lot of lift. In this flight mode it is flying slowly through the air with a very low rate of descent.
In frame "C" the canopy has reached the critical angle of attack. The lift is rapidly decreasing as the canopy begins to stall. In frame "D" the canopy has entered a full stall.
When flaring it is obviously important to have your feet on the ground before your canopy stalls. But let's think about a student canopy. Student canopies are traditionally not supposed to stall when the toggles are held all the way down in a full flare. They are either specifically designed that way or are rigged with extra slack in the brake lines.
What about a slightly smaller canopy, such as one that might be used by a novice or intermediate jumper? If the brake lines are set to the correct length specified by the manufacturer, many canopies in this category also will not stall when the toggles are held all the way down in a full flare. They will simply maintain a slow forward speed and low rate of descent, just like frame "B" in image 1. Even if they do stall it might not occur until the toggles have been held all the way down for a number of seconds: sometimes five or six seconds, maybe even more. Jumpers who fly these types of canopies don't really need to be too concerned about an accidental stall.
You may be surprised to learn that some small, "high-performance elliptical" canopies also will not stall with the toggles held all the way down, or at least not until they've been held there for a few seconds. Whether or not a particular canopy will stall when it is held in a full flare depends on several factors, including the model and size of the canopy, the length of the brake lines, the length of the risers, and length of the jumper's arms.
When held in a full flare a significant number of canopies will simply maintain a relatively low airspeed and rate of descent, at least for several seconds. This knowledge can be very helpful when we talk about flaring high. Look at image 2. In frame "A" we see a jumper reaching level flight with his toes about six feet above the ground. Tragedy? Not really. There are only three things he needs to do: 1) wait wait wait; 2) keep it straight; and 3) FINISH!
"Wait" means stop pulling the toggles down as soon as you realize you've started flaring too high. Save the rest of the flare for later. "Keep it straight" is important, too. You want to look at a point on the ground out in front of you and keep the canopy flying straight toward that point, just like driving your car down a straight road. And when the canopy starts to drop you back toward the ground, just before your feet touch down, push the toggles down and FINISH your flare, as we see in frame "B." In most cases doing this will result in a reasonably soft, stand-up landing as we see from the last two frames. Even if you don't land softly, look at frames "B" and "C" again. What body position are you in when you finish your flare properly? Looks like you're ready for a PLF, doesn't it?
Granted, you will achieve softer landings on calm-wind days if you level off right above the ground, but that is a skill that needs to be developed through practice. An important step in that process is learning to relax and stay focused if you do flare high. This will allow you to keep flying the canopy and finish the flare properly, which will improve your landings in all conditions.
Practice at Altitude
We can see the importance of knowing whether or not your canopy will stall when held in a full flare. How can you find this out? Yep, you guessed it. Under canopy, in your holding area, above 2000', after checking thoroughly for other canopies, push those toggles all the way down and see if that baby stalls. If you've never stalled a canopy before you may want to get some advice from an instructor or coach before trying it.
So try it. Did your canopy stall? No? Makes flaring seem a bit less intimidating, doesn't it? Or was the canopy easier to stall than you expected? If so, you may want to have it checked out by a rigger.
Some canopies are relatively easy to stall, even with the brake lines set to the correct length. If you are jumping one of these canopies then hopefully you've already perfected your landing technique under something more forgiving.
If you can't stall your canopy just by holding the toggles down, does that mean you won't be able to get enough stopping power at the end of your flare? Some people believe so, and Brian touches on this point in his article when he stresses the importance of making sure your brake lines are "short enough:"
Brake Line Settings
"Most manufacturers set the brake lines to allow for a certain amount of slack so that when the front risers are applied with the toggles in the hands, there is no tail input. This, coupled with shorter risers... will prevent you from reaching your parachute's slowest flying speed."
In reality, many popular canopies do not come from the factory with this much slack in the brake lines. For example, people who jump a Sabre2 from Performance Designs or a Triathlon from Aerodyne Research might prefer to have the brake lines lengthened a few inches beyond the factory setting if they use their front risers a lot. Even then, they might not lengthen them to the point where there will be no tail input all when the front risers are used. Even canopies specifically designed for swooping won't necessarily have the brake lines set that long.
Is there really anything wrong if your canopy does have a bit of extra slack in the brake lines? Usually not. Even with the brake lines "detuned" on a student canopy, we still expect students to learn how to stand up their landings. In fact, many popular canopies used by experienced jumpers will also slow down enough for a comfortable landing even if you cannot reach the canopy's absolute slowest flying speed: plenty of people achieve soft stand-up landings in calm winds under canopies that will not stall when the toggles are held in a full flare. Even jumpers who have intentionally lengthened their brake lines for swooping can still achieve comfortable landings in calm winds.
Is there anything wrong with shortening your brake lines? In some cases, yes! Especially if they are shortened so much that they pull the tail down when your toggles are in the full glide position. As an example, look closely at the tail of the canopy in image 3. It seems like the jumper is pulling the toggles down slightly, but a closer inspection reveals that his hands are all the way up.
Having a canopy's brake lines set too short like this can significantly reduce the flare power on some canopies and make them noticeably more difficult to land, particularly on calm-wind days. Excessively short brake lines are more common than many people realize and frequently go unnoticed. It is a common mistake for someone to shorten a canopy's brake lines because it appears that the canopy "doesn't have enough flare at the bottom end," when the real problem is that the brake lines are already too short!
If you're really convinced that your brake lines are too long there are a few steps you should take before having them shortened. On your next jump, after you've released your brakes, put your toggles all the way up against the guide rings and look up at the tail of your canopy. Don't forget to watch where you're going and look out for other canopies. If your canopy looks like the one in image 3 then forget about having the brake lines shortened. They probably need to be lengthened instead.
If your canopy seems difficult to land you can also have a rigger measure the suspension lines and compare them to the manufacturer's specifications. It's possible that your canopy has simply gone out of trim and is due for a reline.
Once these steps have been completed then get some of your landings videotaped and see if you are finishing your flare properly. Look at the jumper in image 4, just as he is touching down. Does he need shorter brake lines to get a better flare? No, he needs to push his toggles all the way down and FINISH flaring before he touches down. Most jumpers finish their flares at least slightly better than the jumper in image 4, but not finishing completely is one of the most common flaring problems. Brian makes a very good point about this: "the brake lines can only work if they are pulled."
If you are still absolutely convinced that you need shorter brake lines then follow another good piece of advice Brian gives and only shorten them an inch at a time. Make several jumps, preferably in different wind conditions, before shortening them any more. And remember that you can significantly reduce a canopy's flare power by shortening the brake lines too much.
There is usually some excess brake line left over when the toggles are tied onto a canopy, and there are front row seats in purgatory for people who cut this excess brake line off. That excess line should be finger-trapped back into the brake line or secured in a similar fashion in case the brake lines need to be lengthened later on. A qualified rigger should know how to do this correctly.
What else might affect your landing on a calm-wind day? Brian discusses the importance of keeping the canopy flying straight during the flare, and not allowing it to bank or turn. He emphasizes this by stating that "any tilt in the roll axis will result in a premature stall of the parachute…. due to an effect known as 'load factor.'"
If we are going to introduce "load factor" into our discussion then let's do the math. At a bank angle of 30 degrees load factor will increase stall speed by approximately 8%. A bank angle of 45 degrees will increase stall speed by 20%.
The exact stall speed of a ram-air canopy will depend on several factors, but let's use 5 mph (8 km/h) as an example. In that case, a 30-degree bank angle while flaring will only increase your stall speed by 0.4 mph (0.64 km/h). To increase stall speed by 1 mph (1.6 km/h) you will need a bank angle of 45 degrees while flaring, which is a pretty sporty maneuver by most people's standards.
While load factor might sound important, is a 0.4 mph increase in stall speed a significant consideration when landing your canopy? Probably not. Nonetheless, is it important to keep the canopy flying straight while you flare? Absolutely. Even without a stall occurring, banking or turning while you flare can cause you to touch down at a higher speed. You will probably also land with your body off balance, and fall over sideways.
A bank or turn during the flare is most commonly caused by reaching for the ground with one foot. You can usually see yourself doing this on video, and might even feel yourself doing it while it's happening. This problem can easily be avoided if you focus on looking straight ahead, keeping your body straight, and flaring evenly.
What should your feet be doing? Do you need one foot below you and one out in front as you prepare to touch down? That probably will happen naturally just as you stand up at the end of your flare without putting any extra effort into making it happen. And putting extra effort into making it happen could cause you to reach for the ground with one foot.
If you need to think about anything while you're flaring, think about keeping your feet together as you get into level flight, and continue keeping them together while you fly the canopy in a straight line across the ground as far as possible. If everything is going smoothly then as the canopy sets you down you can just stand up as if you were getting out of a chair. Your feet know what to do.
Look at image 5 below. We see a jumper flaring his canopy with his feet and knees together, knees slightly bent. Looks like he's simply maintaining a good PLF position, doesn't it? As he finishes his flare and the canopy sets him down, his feet come apart slightly to accept his weight.
Harness Body Position
What about leaning forward in the harness? Is "freeing your body from the pitch of the system" a crucial part of flaring? Look at image 5 again. A pitch change does occur when the nose of your canopy tilts up at the beginning of the flare. This pitch change is what puts the canopy into level flight, and the pitch change is actually created by the movement of your body under the canopy. In fact, it can be extremely helpful to view your body as an integral part of the parachute system instead of separating yourself from it. Feeling your body swing in conjunction with the canopy's movement is an important part of doing effective practice flares.
If you like to lean forward in the harness and it seems to help your landings, that's fantastic. It feels nice and looks cool. But it's also not a problem if you simply sit still in the harness and let your feet swing out slightly in front of you as you flare. Your body will rock up onto your feet as your feet touch down and accept your weight. You can either "lean forward into the experience," as Brian suggests, or maintain a more laid-back pose if you prefer. Whichever one feels more comfortable is the best one for you.
The technique Brian calls the "Seagull Landing," where you dip down below standing height then rise up again at the end of the flare, also feels good and looks cool if you do it correctly. You'll do it correctly if you develop the technique naturally while you practice good basic flaring skills. Putting too much conscious effort into achieving a "Seagull Landing" is similar to the belief that you must level off right at ground level every time: it can result in the same problems and bad habits. Most canopies will slow down just fine if you level off a comfortable distance above the ground and simply maintain level flight through the remainder of the flare.
In general, it might help to stop thinking about a "no-wind landing" as being significantly different from a "normal" landing. The basic skills that you use to land in stronger winds will also help you land softly in calm winds. Any bad habits you develop might not hurt your landings too much when there is some wind to slow you down, but those habits are usually still present and affecting your flare to some degree, and can be eliminated by practicing proper techniques.
Eliminating those bad habits by keeping things simple, letting yourself relax, and focusing on good basic flaring techniques will go a long way to improving your landings in all conditions. Soon you'll be just as confident landing on calm day as you are on windier ones, and you may even start to prefer calm-wind landings.
Experienced skydiving instructors and coaches, like those in any other sport, develop their own opinions, philosophies, and teaching methods. The advice you get from one person may be quite different from what someone else tells you. This can actually be a good thing sometimes, because the advice that helps one person may not be equally helpful to others.
The most basic, fundamental principles of aerodynamics can be used to describe the flight of any wing, so some of the things you learn about one canopy will certainly apply to others. However, specific performance characteristics can vary greatly from one aircraft to another: a 210 sq. ft. canopy does not perform exactly the same way as a 107, and a Triathlon does not perform exactly like a Sabre2. A Sabre2 does not perform exactly like a Lotus, and a Lotus does not perform exactly like a Twin Otter.
When discussing canopy performance and flying techniques the most important piece of advice I give my students is this: don't passively accept anything anyone says, including anything that I tell you. Think about it, and if it doesn't make sense keep asking questions until it does. More importantly, experiment in the air and see for yourself if it's really true.
Also, remember to breathe.Scott Miller
- Direction of Commander, Naval Air Systems Command, United States Navy. Aerodynamics for Naval Aviators. Washington: Naval Air Systems Command, 1960. Revised 1965.
- Germain, Brian. "Surviving the No Wind Landing." Dropzone.com. Sep 05 2007. (accessed October 13, 2007)
More articles in this category:
- Landing Pattern – Landing Approach Simulation - by Alexander Shyrokov (Posted: 2009-10-01)
- Another Look at No-Wind Landings - by Scott Miller (Posted: 2007-10-16)
- Surviving the No Wind Landing - by Brian Germain (Posted: 2007-09-05)
- Wings Level - by Skratch Garrison (Posted: 2003-10-26)
- ZP Canopy Landing Tips and Techniques - by Pat Works with John LeBlanc (Posted: 2003-08-22)
- What To Do When the Wind Picks Up - by Gary Peek (Posted: 2003-08-22)