March 1, 2003

The physics and skills of a graceful landing
By Rohan Holtkamp and Dr James Freeman

Whilst at the landing paddock the other day, I couldn’t help but notice that some pilots don’t land, they "arrive". This is not just a localised occurrence The carnage we have witnessed in goal paddocks around the world is testament to the fact that even some brilliant XC pilots could do with a bit of a refresher on their landing technique.

Along with this, there seems to be a spreading misconception that hang gliders are hard to land. Bullshit!

So are they doing something wrong or is it the equipment? The answer is perhaps both.

Some models of glider aren’t as easy to land because they require more accurate flare timing than others, or perhaps have a light and vague pitch feel. These gliders require the pilot to be more sensitive to feedback from the glider prior to flare. This sensitivity is optimised when the pilot has a gentle touch on the controls. A gentle touch on the controls prior to landing is promoted through confidence.

Ah confidence. It's easy to be confident when you're landing well. But what can you do if you're not landing well, but simply arriving to the sound of bending alloy. To build your confidence requires practicing landings, and more specifically several successful landings in a row.

Most pilots do not practice landings. They fly the whole day then have a single landing a the end. Practice requires repetition and dictates making several landings in a row. Towing is ideal for this as you can make many landings without ever having to setup your glider more than once or carry it very far, but a training hill and some sweat works just as well. Top landings are usually performed in stronger winds and don't teach flare skills well.

The best results from practice can be gained with feedback from an experienced hang gliding instructor/coach, or alternatively using this guide combined with video footage of your landings for self-assessment. A trap with using a video is that when an unsuccessful landing is viewed too often it is easily etched into ones mind only to reappear in the form of action during a similar stressful moment, such as the next landing. Get your camera-person to edit for you.

Why do some pilots land great and make it look easy every time no matter what they are flying?
Assuming basic skills, most pilots should be able to fly the glider, wings level, down to an altitude that’s safe to fall from. There are five basic skills to display before you become a "landing legend."

Skill One - Make a Good Approach
It is often said that a good landing follows a good approach. So what is a good approach. A good approach is one that gets you on a final glide from say 20 feet, into the wind, wings level, holding some extra airspeed, unzipped, hands on uprights (or one hand down and one hand up), with no obstacles to worry about. From this position all your mental focus can be on making your graceful landing.

Skill Two - Look Ahead, Round Out and Hold Off
In all aviation many landing problems can be traced to looking at the ground and as a result flying straight into it. Accurate judgement of height requires utilising our peripheral vision. We spend half our lives at standing height and know exactly what the world looks like out of the corner of our eyes when at this height. As this is the exact height that we wish to make our hold off at we already know how to accurately judge this height. Looking straight down it is very hard to judge height, let alone control the glider's heading.

We set up our landing with a good approach holding some extra airspeed above trim. As we approach the ground we round out (decrease our descent rate) by relaxing our grip and aim to hold a constant altitude (feet just above the ground) by gradually bleeding off our excess airspeed.

Skill Three - Find Trim by Relaxing Your Grip
You must be willing and able to reliably slow the glider to trim speed. This is an airspeed that’s 10 - 15% faster than stall speed. Trim speed is the speed that the glider flies with no pilot input, which means all pilot weight hangs from CG only.

A correctly trimmed glider is essential. When landing a poorly trimmed glider it is far harder to establish the correct airspeed prior to flare. Trim variations can occur through sail shrinkage or incorrect adjustment of frame, battens or CG/hang-point. These variations can occur through normal and abnormal wear & tear. Gliders that have soft batten or frame material can easily have the batten or frame shape altered from a simple nose-in and consequently suffer an alteration of the pitch stability and trim speed.

To make sure your glider is trimmed correctly, with adequate altitude flying prone and in smooth conditions, allow it to fly at trim (no pilot input) by completely relaxing your grip and allowing the glider to fly at whatever speed it wants. The glider should handle at least 50mm of forward control movement (at the base bar) from trim position before stalling. If you have an airspeed indicator it is easier to determine 10-15% faster than stall.

After correct adjustment, to find trim speed you should only have to relax your grip. If in doubt about any adjustments, ask your instructor, dealer or manufacturer.

Skill Four - Be Willing and Able to Fully Stall the Glider by Pushing Up
You must be willing and able to raise the nose of the glider to full stall/ flare angle of attack, at least to land in light winds.

Often the inability to raise the nose can be due to the pilot hanging too low. This can appear as if the pilots’ arms are too short. (sound familiar?) The pilots’ arms appear too short because most of the arm length is taken up just reaching out to grip the uprights at the wide part of the A-frame!

Additionally, most A-frames are raked forward so the pilots shoulders, in trim, are even further back in relation to the grip – making their arms appear even shorter. It’s hard to get the nose up (by pushing out & up) if the arms are already straight!

After adjustment of the hang loops, the correct chest/base bar clearance (in prone) can be set by adjusting the head-up/down rope, and should result in a slightly feet high attitude (compared with the horizon, in trim position). You will notice that the same pilots who land great have a slight feet high attitude whilst in prone. This also makes them glide better and get higher (less drag) than the pilots that don’t align their harness with the airflow. Some harness designs do not have a head-up/down adjustment so the leg loops may need to be tightened to raise the pilot whilst in upright position. If this cannot be done due to the excessive girth of the harness forcing the leg loops to be uncomfortable in prone, trade it in for one that fits properly. If in doubt see your instructor, dealer or manufacturer.

Additionally, inability to raise the nose can be due to the pilot only pushing out. For a more positive nose up result, the pilot must push mostly upwards, with the grip at ear/eye height prior to flare. Hands must be open enough to avoid loading the controls with any pilot weight, but tight enough to avoid slippage.

Many pilots are scared to flare. When you flare the glider will climb a little as it converts kinetic (moving) energy into potential (height) energy. This is normal. If you have followed the preceding steps and flare a correctly trimmed glider from trim position the glider will climb no more than one or two feet before the combination of a high angle of attack and climbing out of ground effect leads to a crisp stall.

In stronger winds a full flare is not required but most pilots have little difficulty landing in a good headwind anyway. Don't do a full flare if it is blowing 20mph unless you want to look like an upside down turtle!

Skill Five - Be Ready to Run But Keep Your Legs Behind You
You must be willing and able to run a few steps so as to let the glider settle behind you when your feet touch the ground, however if you swing your legs forward in anticipation you will shift your weight forward and negate your flare thus creating a self fulfilling prophecy.

If you have done all of the above correctly but there is greater groundspeed than the legs can keep up with, try landing into the wind!

Summary of a graceful landing technique.

• Ensure your glider is trimmed properly, and harness is set up correctly.
• Make a good approach.
• Approach the landing zone with faster than trim airspeed.
• Make sure wings are level and heading is consistently along your intended (adequate length) runway.
• Look up, round out, hold off. Relax you grip and bleed off extra airspeed smoothly to level off at a height you feel safe to fall from. (less than 3 ft for me).
• Find trim speed by relaxing your grip on the controls, identify you are touching only the back of the uprights and all your weight is in the harness.
• Flare by pushing UP and out - swiftly if a lot of slowing is required, - slowly if a little slowing is required, - no flare is required if no slowing is required (like on a windy day).
• Keep your legs behind you.
• Coasting run to a gentle stop if required.
• Wave to the spectators as you carry your glider over to park it.