The foundations of gliding flight go back to well before the Wright Brothers initial success at Kitty Hawk. Otto Lilienthal made over 2000 experimental flights before the 20th century was born.   This data, along with the results of their own gliding experiments provided the Wrights with the basic foundation of knowledge that made the first powered flight possible. Recreational gliding was widespread throughout Europe in the early part of the 20th century. It was widely used in Germany during the 30's, not only as a form of   recreation but as a way of training pilots without violating the restrictions put in place after world war one.

Today, recreational soaring is a small but important part of the recreational aviation community. The old time pilots of yesteryear would be very surprised to see just how far things have progressed. The modern composite machine of today is extremely efficient. L/D ratios close to 50 are common in today's sport machines. Free distance cross country flights have been made in excess of 1500 miles, maximum speed around a 62 mile course has been clocked at over 145 mph. The current world record altitude record for an open class sailplane currently stands at 49,009 feet. All very impressive for what is essentially a solar/gravity powered machine.

In the early days gliders were foot launched from the sides of hills, much in the way that hang gliders are handled today. In modern soaring operations there are two basic ways to get to your starting altitude, winch or aerotow.  In a winch launch the sailplane is attached to a long cable that leads to a powerful ground mounted winch. As the winch reels in the towline the glider ascends rapidly and at a very high angle of attack to an altitude that's determined by the length of the towline. This method is, shall we say "exciting" and timing is very important. The main advantage is low cost and almost anytime operation. Using aerotow the sailplane is linked to a small powered aircraft with a 200' towline which tows the sailplane to altitude. This is the most common method in the US and offers a lot of flexibility. It also takes some time to learn.  If you think about it, you're being asked to fly in formation with another aircraft at a speed that's probably going to be on the high end of the flight envelope for a typical sailplane trainer. It's the first thing you learn to do and it can be a very humbling experience. Ground launches similar to a winch launch but using a moving vehicle can also be done but it's not a very common method, at least in the US.

How you get airborne in the sim world will depend on what sim you're running. X Plane simulates both winch and aerotow methods so that's pretty straight forward. These options are not available in MSFS so you'll have to slew by pressing "Y" and then "F4" while watching your altimeter to get to your starting altitude, allowing a little extra to recover from the stall that comes from being dumped at altitude with zero airspeed. For a little more realism in MSFS you might look for aircraft equipped with Milos Kock's VET (Virtual Engine Technology) add-on.

Once you're at altitude and on your own you'll want to trim for best glide speed and start getting a feel for the machine. You'll find it to be very responsive, more like a fighter then a general aviation aircraft. As you fly the machine you'll also notice that turns are not what you're used to. High bank angles are the norm and you'll be using the rudder a lot. Because of the low speeds and high aspect ratio wings, sailplanes create a lot of adverse yaw in a turn. Proper coordination between stick and rudder is a must. You've probably noticed that bit of yarn attached to the windscreen in the picture above. That's a yaw string, a primitive yet very sensitive indicator of airflow. Your simulated sailplane will have one too and using it is simple, just play the rudder pedals to keep the string straight. Also keep in mind that it works opposite to the standard ball type slip indicator found in powered aircraft. In that case you "step on the ball" to take out the yaw. Because a yaw string shows the actual air flow you need to step on the pedal that's opposite from the direction the yaw string is pointing. A little confusing at first but you'll soon get used to it.

If you're an experienced sim pilot in powered aircraft, running an approach and landing in a high performance sailplane will take some getting used to. You can't go around so flying a proper and repeatable pattern is a must. Landing a sailplane safely is all about energy management. Airspeed and altitude are the fuel in your tank. The basic idea is to turn final with extra energy that can be dissipated as needed to reach your desired touchdown point. To give you an idea of how it all works, here's a trip around the pattern at Bremerton Washington, Digital-Flight's home field.

The Initial Point is located directly opposite the far end of the strip at an altitude of 1600' AGL. Fly downwind at a speed that's approximately 10 to 15 knots above best glide speed for your aircraft. In the ASW 28 that works out to between 60 and 65 knots. Keep tracking your touchdown point visually over your shoulder until you reach the 45 deg. line indicated on the chart. Maintain speed on base, timing your turn to final as best you can. Once you've turned final in a high performance model such as the ASW-28 you'll be at about 1000' AGL and looking at the following site picture.

Notice that the VASI lights are indicating you higher then you'd normally be at this point in a powered approach. That's good because it means you've managed your energy well and are at this critical point, ahead of the curve. Now the only problem is, how do you get down? You could just drop the nose and dive in but you'll build up so much speed that you'll float the entire length of the runway and then some. The secret to getting down is to increase your sink rate without increasing your airspeed. This is accomplished by deploying the dive brakes or spoilers as they are sometimes called. These are simply vertical slats that when deployed kill the lift over a segment of the wings, adding a considerable amount of drag in the process. If you have a retracting landing wheel drop it now and then fully deploy the dive brakes. From here on in it's simply a matter of tracking the centerline and playing the dive brakes on and off to maintain your touchdown point. If you've ever watched a real sailplane on final you'll have noticed the drive brakes blinking on and off over the wings as the pilot finenesses his sink rate down to a perfect landing. To make this easier and more realistic in the sim you'll want to map the dive brake/spoiler to your throttle axis. This will give you the proportional control rather then the simple on/off default. I would also recommend reversing this axis so that the full forward position equals full dive brake retraction as it does in a real sailplane.

Once you reach a point a few feet above the strip, stow the dive brakes. In many sailplanes activating the dive brakes also activates the wheel brake. You don't want to touch down with that locked. Gently flair and allow the plane to settle in to a smooth touchdown. Once you're down the game isn't over. At this point you're balanced on a single wheel so brake carefully, using the rudder to control direction while you work the ailerons to keep the wings level. As your speed decays this will require larger and larger control movements as the surfaces decay in effectiveness. When you're slow enough gently turn off the runway and try and not let a wing drop until you've almost come to a full stop.

Now that you've mastered the basics around the field it's time to deal with what is after all the point of the exercise, that is, staying aloft. In still air at it's best glide speed of 50 knots the ASW-28 will deliver an L/D Ratio of 45:1. That means for every 45 feet you fly forward you'll loose 1 foot of altitude. Starting at a release point of 5000' and disregarding any vertical air movement you should be able to make a distance of 37.5 nautical miles before touching down at sea level. That's pretty good but to extend your flight time or to cover cross country distances you'll need to be able to gain altitude. That's done by seeking out areas of rising air. Upward moving air can be supplied by thermals, ridge or wave lift.

Thermals are normal atmospheric convective motion caused by the rising of heated surface air. Go out on a warm sunny day when there's lots of isolated cumulus clouds about and not too much wind. What you're seeing are the tops of individual thermals that have gone high enough to cool and produce visible vapor. They will typically form over areas such as parking lots, rock, plowed fields, any area that tends to get warmer then the surrounding landscape. The trick for the soaring pilot is to find the thermal and then once found, to stay within the column of rising air. This is done using the sailplanes primary instrument, the variometer. This is basically a very sensitive vertical speed indicator. When you enter a thermal you'll be able to tell by the sudden positive climb rate indicated on the vario. When you hit lift fly straight for a few seconds and then bank into a steep 45 degree turn to the right or left, your choice. If you loose the lift then you've probably turned he wrong way and flown out of the thermal. Come around to your starting point and try it the other way. After a bit of feeling around you should be able to center yourself within the rising air and ride it until it gives out. When conditions are right relatively long distances can be covered by flying from thermal to thermal, as needed to reach your destination.

Ridge lift is formed when a horizontally moving air mass meets a vertical obstacle such as a ridge or hillside. The sailplane pilot will work back and forth along the ridge to stay in the air. This is challenging low level flying to be sure. Unlike thermal lift, ridge lift generally doesn't extend very high however if the ridge line is long or there are others in a chain then extended distances can be covered. The one advantage that ridge lift offers over thermals is that it's a bit more reliable and easier to find.

The big daddy of rising air systems is wave lift. You may have seen the unusual "stacked plate" lenticular cloud formations that sometimes form over high mountain ranges when conditions are just right. Those plates are formed by the largely laminar flow of the air rising over the range. It's called wave lift because after the air mass travels over the obstacle it sets up a wave pattern of moving air that can extend for over a thousand miles. This type of system can be extremely powerful and extend to high altitudes. Large wave systems are used to set both soaring altitude and distance records.

X-Plane provides thermals as a basic part of it's weather options allowing you to set coverage percentages and strength. Ridge lift is also automatically generated and it's strength is based on that set for the thermals. In MSFS things are a little more flexible but also a little more complicated. Thermals and ridge lift are a part of the scenery. Places like the ocean facing cliffs just north of San Francisco are obvious but to really do it well you'll want to download ready made thermal scenery or make your own using Max Roodveldt's excellent thermal creation utility, Thermic. As far as I know, no flight sim currently models wave lift so that's something for the future.

This introduction just scratches the surface of the art of soaring. There's a lot more that can be done in the area of cross country techniques, performance prediction and contests that will be covered in a follow up article. For now, grab a sailplane and go bust some thermals!

ASW-28

Thermic

SOAR web site

X-Plane Sailplanes at the ORG

In X-Plane go to "Settings", "Set joystick axis and equipment", press the joystick button you want to use for activation and then select "speed brakes" from the list. Note that assigning the dive brakes to a variable controller such as the throttle is not supported in X-Plane at this time.