Richard H. Johnson  -Draft 9, 9/19/01


In recent years there have come on the market a number of excellent PC based flight simulation programs that have the capability of aiding airplane pilots to either maintain their proficiency, or to become more proficient at flying. Relatively recently one excellent program has been written exclusively for sailplane pilots. A pair of German aero engineers wrote it as a spare time love-of-the-sport project. Their names are Detlev Schwetzler and Uwe Milde, and they have really done an outstanding job with their latest creation. Sailplane Flight Simulation, Version 4. It has just recently been released, and Jim Gell of GEE Wiz, Inc. is the US distributor of the program. The prior SFS -Version 3 was quite good, but Version 4 is, in my opinion, really excellent.

By focusing on the unique elements of soaring flight the programmers have developed a tool that is useful to student pilots as well as experienced cross-country competitors.  Student pilots can practice flying the tow, pattern flying, and landings.  They can learn the techniques of locating lift and centering in a thermal.  For many student pilots, the simulator has provided an excellent means for reviewing and practicing the lessons learned in the cockpit.

For the more experienced pilot the program is a great tool for honing the decision-making skills of cross-country flying and competition.  Using the common tools of a speed to fly calculator, GPS, and reviewing the available out landing areas the pilot can decide whether to stay in lift, move out further on course, or start searching for a landing site. 



                Four different sailplanes are offered for the PC users choice. They vary from a very basic and still popular US trainer, the venerable Schweizer 2-33, to the modern and complex 15 meter ASW-27 Racing Class sailplane. The good news for the American students and new pilots is that the 2-33’s cockpit is equipped with an American sensitive altimeter and a standard knots airspeed indicator. The other three sailplane cockpits are equipped with metric instruments only, but I find them easy to use. Just remember that 100 meters of altitude is equal to 328 feet, and that 100 kph of airspeed is equal to 54 kts. Recent good news is that the three metric sailplanes are being converted to our usual English units, at least for the American market.

                All of the candidate sailplanes have realistically configured cockpits. The airbrake, flap, and landing gear handles are shown on the proper sides of their cockpits, and even their handle movements are shown when actuated. The higher performance planes also carry water ballast, which can be dumped during the flight as necessary, or in preparation for landing. The only liberty taken was to show the pitch trim handles as being located in the instrument panels so that the PC user could easily see them. Even the flight wind noises are realistically duplicated, especially when flying at high airspeeds, when the airbrakes are extended, and when the landing gear is extended. High ‘G’ maneuvers will have the wings bending upwards as the loads build. When redline airspeeds are exceeded, the wings come off, and the unfortunate PC pilots have no parachutes!



                The SFS-4 program does exceptionally well there, but the available flight area is only over a northern 200 by 200 km area of Germany. The flight area includes Oerlinghausen and Paderborn in the northwest, to Muhlhausen in the southeast. Beautiful ICAO flight maps (like our sectional charts) are provided showing every road, river, airport, hill and mountain in that area. The terrain is presented in a good three-dimensional view that makes ridge soaring close to the slopes quite realistic. When on a cross-country flight, navigation is easy because a tap of the map key will show the pilot his current location and direction of flight. If one has declared a goal or turnpoints, those will also be shown on the ICAO map. The pilot also has use of a GPS system to aid in navigation which includes items such as the coordinates of the current location, distance and bearing to the turn points, average speed, and dead-air gliding distance.  There is also a separate speed-to-fly calculator available.



                The program appears to accurately depict about 40 or 50 currently active German glider airfields, and a takeoff or landing can be made from or on any of them. Safe landings are also permitted at any of the 200 or so non-glider airfields shown on the ICAO maps. When needed the pilot can locate suitable off-airport landing fields with the press of a key.  This is something that’s useful to do from time to time a cross-country flight as some areas have fewer useable landing areas than others. An off-field landing elsewhere, even performed gently, is scored as a damaged glider, and a fire engine is dispatched for your rescue!

Most of the glider airfields only provide for winch launching, but quite a few have a towplane option. I recommend the towplane option for most US pilots because of its realism, and that is what most of us know how to do best. The towplane can be steered by pressing either the X or Z keys. My currently favored simulation flights are to aero tow the ASW-27 to about 600 or 700 meters, climb in a thermal to about 1300 meters before passing through a 1 km high start gate at near red-line airspeed. From there continue on to a pre-declared goal’s finish gate about 50 km away, again at high airspeed. That is both enjoyable and good practice for contest and racing pilots, especially on a winter or a rainy day!



                To make the simulation very real, air traffic is also included. It is up to the pilot to avoid collisions, both in the air and on the ground. Glider winch launchings, other sailplanes, and tow plane traffic has to be reckoned with just as in the real world. A unique program feature is that one has an option of racing with additional computer generated sailplanes flying along the same designated task. It is not unusual to join another sailplane in a thermal, or to be joined by one in your thermal. At any given time you are likely to see other sailplanes, sailplanes on tow, low-level fighter aircraft, commercial airliners, balloons, and aerobatic planes.




                The thermals and cumulus clouds are depicted according to the thermal development stages that are outlined in the epic Cross-Country Soaring book by Helmut Reichmann that was first published in 1978. He was an outstanding sailplane pilot, and that was the year that he won the 15 Meter World Championships in France.

                The first thermal stage is cloudless, with only a warmed air puddle resting on the ground. By the 4th stage a small cumulus cloud begins to form, and by the 8th stage the cloud is disintegrating with only downdrafts under it. That is very realistic, and it provides good practice at cloud reading. The really beautiful part about the thermals in this program is that the user can exercise a program option that allows one to actually see the thermals in any of their development stages. I am fascinated by that option, and find that flying with it operating is much more enjoyable!  Won’t someone please develop such an instrument for us soon? We all know that it will be available someday, and our contest rules already prohibit its use during contests.



                The program can be run using the standard computer keyboard for flight control of the sailplanes, but that is cumbersome and unnatural to do. A very satisfactory control option is to add a conventional inexpensive Joystick for pitch and roll control. The program thereby operates the sailplane in a coordinated mode, and the yaw string stays nicely centered. I like that! The 3rd control mode is to add rudder pedals to the joystick and really fly the sailplane with 3-axis controls. I bought rudder pedal hardware recently, but I have yet to figure out how to make them work in the program. That is likely my fault, and I will keep asking advice and working on that problem.

                A couple of very nice improvements from the previous version are available if you have a joystick with a hat and a throttle.  The hat allows you to move your view in just about any direction which is useful when clearing the area before trying some of the flight maneuvers described below.  The throttle actuates the spoilers in a very smooth manner giving the pilot excellent glide slope control for landing.



                One does not need a special view-changing button on the Joystick controller because the keyboard F2 and F3 keys are assigned the scan functions. Pressing the F2 key once shifts the pilot’s view about 15 degrees to the left. Each subsequent repeated pressing of that key increases the pilot’s lateral viewing angle by about another 15 degrees. Holding the key down slews the vision area in a smooth motion. That is quite handy when flying in a landing pattern or looking for air traffic. The F3 key does the same thing, but to the right. By holding the CTL key down at the same time, and pressing the F2 key scans the view up, and the F3 key scans the view down. A bit cumbersome, but it works for me.



                One can practice aerobatics such as loops, rolls, and spins quite safely with this program, but exceed structural or airspeed limits and the wings come off! The spins appear to be realistic to me, and with the spin mode option open, even the docile 2-33 will spin when provoked. The rudder pedals will likely facilitate spin recoveries much better, and certainly more realistically than the joystick alone permits. The nice thing about the program is that one can try outside-of-the-envelope maneuvers, and no one gets hurt.

 One can also practice boxing the tow plane wake while on tow. Another training element for aero towing is the way the sailplane can lift off before tow plane does.  If the user allows the sailplane to rise too quickly after lifting off, the tow plane will nose over bringing that tow to an abrupt end!




                The program has a very commendable training option: that is, the introduction of unanticipated rope breaks at unexpected times during either winch launch or aero tow.  The user has a menu option to set the “Probability Of Rope Break” lever anywhere between “Never” and “Always”. That is certainly exciting and excellent practice for everybody, no matter how experienced. The first time that it happened to me was during a winch launch, and I failed to recognize it soon enough. The result was a full loop after the rope break with my sailplane just missing the ground during the pullout.



                There are several flight tasks that are available: Free flight, Target, Target-Return, and Triangle.  When setting up one of the declared tasks you can also set up your competition with any of the available planes and various skill levels.  You will see these folks while you are out on the course, sometimes marking the lift for you.  But be careful, as they may be one of the less skilled pilots who are marking less than desirable thermals.  Still, it is great fun to get into the bottom of a thermal with a couple of planes turning above you and see if you can get to the top before them!

                Turn points can be logged with either your GPS or using an onboard camera (which can also be used for photographing any interesting scenery you happen to come by).

                Once you have completed your task (or landed out) you will get a complete summary of your performance.  This will include a plot of the actual flight path flown, a barometric chart of your flight, and the competition results (all properly handicapped according to the aircraft flown). 



                As you can imagine, large amounts of memory, processing speed, and a modern graphics card

 are needed to run this program well. However, those items are becoming more affordable each day. My 800 MZ AMD processor and Nvidea G-Force graphics appear to run the program well on my current PC.

                The program will work with any graphics card that supports the full OpenGL standard, such as the Nvidia G-Force cards. Detailed system requirement and a downloadable demo are available at http://www.sfspc.de.



                In my opinion this new Sailplane Flight Simulation – Version 4 is a whole lot more than just another enjoyable computer game. It can both significantly reduce the amount of flight training that a pilot needs to safely solo, and it can help experienced pilots learn more and maintain their proficiency. Hopefully, its use can help reduce the deplorable start-of-the-season sailplane accidents that we too often see each spring.

Thanks go to Uwe and Detlev for writing this fine sailplane flight simulation program, and also to Jim Gell for assisting in the Americanization of its instrument panels, other program improvements, and helping with the preparation of this text. Jim can be reached at geewiz@wwnet.net should you wish to order a copy, or need any assistance with it.