Aircraft expansion pack for Microsoft FSX

"The Discus is not overly simple to fly, but once you learn its characteristics you will have a vehicle with which you can comfortably set yourself challenges. By the same token, when you put it all together and are successful at whatever you set yourself, you really feel a sense of achievement"

I've often been asked if I've done any gliding in FSX, the short answer has always been “haven't you heard of Condor?” Because gliding in FS has never worked, so to speak. Still air, horribly unrealistic thermal activity and a towplane that heads off on the runway heading seemingly intent on getting you out of gliding range of your home airfield. Condor, on the other hand, copes with these areas well, has a range of gliders with excellent flight models but is not up to the standard of FSX in terms of graphics or scenery enhancements. So what can we do about this? Well, granted, FSX now has so many VFR scenery packages that it is becoming easier to navigate by terrain features, so what we really need is a decent looking glider with an accurate flight model, completely replace the thermal / ridge lift elements of FSX with a product which gives you rising and falling air according to a large list of variables so that the air around you is not only moving, but also constantly changing the way it is moving. Oh yes, and we want something better than the default towplane. Sound like I'm asking a lot? Well okay, I probably am but the fact is it has already been done. Aerosoft's DiscusX comes with a winch-launch add-on which is realistic and straightforward to use. In addition to the Aerosoft Discus package, the freeware CumulusX! By Peter Lurkens is highly recommended – it changes gliding within FSX totally.

Where to pitch this review was something that bothered me – it may seem at times to be too simplistic for those of you that have flown gliders in real life. For those that haven't, hopefully it will give you a bit of an insight into our 'sport'. The aim is to hit the middle ground, if I'm off target I apologise in advance. So let's start by breaking the package down a little bit.


The Discus package is to the Aerosoft standard – an executable file, which brings up the screen to enter your details, locate FSX on your computer and then set it to install. This is all very straightforward, as you would expect, and no problems were found. Earlier versions of the installer would then place ten aircraft into your simobjects folder, a combination of pure sailplane, the BM (powered) and BT (assisted) variants. It is important to differentiate here between the BM and BT models – both have a retractable engine but the BM is the only one capable of unaided take-off. The engine on the BT is purely to assist the aircraft between thermals if necessary.

The Discus currently available is version 1.5, and that is the one being reviewed here. Anybody still running an earlier version, you really should re-download, because this latest resolves several issues and also adds three aircraft to the package, namely a British version of the basic Discus, the BM and the BT.

When installed into FSX, the Discus takes up a total of 862Mb (including the manuals), with WinchX using 4.03Mb. CumulusX will require an additional 2.12MB.


I first got to know the Discus whilst working at the Junior National Gliding Competition in the UK. At the time, I was flying the L13 Blanik (which I still rate as probably the easiest and most fun aircraft I have flown). Back then, the Discus was shark-like in appearance, with graceful, curving wingtips. These days, we have winglets which seem to grow from any aicraft you can imagine and (I think) somewhat detract from the clean lines of the earlier Discus. However, that is certainly not Aerosoft's fault – they have modelled both versions. And they have done it well.

As you would expect from a performance glider, the exterior of the Discus is quite plain. Being made of fibreglass, there is not much opportunity to make use of the FSX speciality bump-mapping. However, that is not a criticism – in fact it proves very beneficial. Some people will only fly from the cockpit, others want to wander around the outside. To accommodate this, the vast majority of FSX releases are fairly heavy on external detail, but that is not the case here. Again, it is not a criticism – on the smooth fibreglass hull of a glider there should be very little detail to pick out.

Where you would expect detail, it is there – the undercarriage, for example, is well modelled with every detail down to the cable for the brake drum, as you would expect. It is the texturing in this area which really shows attention to detail. Much as it may have been tempting to keep the aircraft clean and shiny all over, the fact that gliders regularly operate from grass strips leaves its tell-tale mark in the form of grass stains on the undercarriage doors. Not enough to pick up on first inspection, but when you start poking around you'll see it. And directly behind the undercarriage is a small layer of dirt, kicked up by the wheel. Being so low to the ground, it is to be expected, of course. But it did make me want to get the bucket and soap out, just for a minute.

Both the BM and BT models have crisply detailed engines, though in truth there is not really much to model with such small power plants. Not only do they look right, but their operation is smooth and straightforward.

The textures, in the majority, are lower resolution than you would normally associate with such a high quality model. The only areas which are specifically high-res are those to which markings are applied, or which are moveable areas (undercarriage, airbrakes, engine). The bonus from this for those with lower-spec systems is that it does not impact on frame rates (or alternatively, it frees up resources which are better used elsewhere), a very sensible decision because lower-res white is very much the same as high-res white. The key word here is 'optimised', which this aircraft is without affecting the quality.

The only area which I feel lets down the model is the joints between major structural parts. The joints are generally crisp, though in real life often covered by tape so virtually invisible except for close-up inspection. If you inspect the Discus from close-up, you will see a distinctly low-res grey line which represents the join. From a distance, the effect is really rather good, giving an idea of the joint showing lightly through the tape. Close-in, however, it is obviously just a low-res texture. Whether you find this a problem or not is down to personal preference; I tend to fly from the cockpit (where most aircraft are flown from!) and so prefer to have both time and resources spent getting that just right. Those who like to make their way around an aircraft from the external viewpoints may be slightly disheartened at seeing these dull grey join lines. But let us drag you inside for a moment so that you can hopefully appreciate the benefits that they bring.


Here the Discus really excels. I'll start by saying that I really dislike people inside aircraft from the internal views. They are needed from the outside view (no Marie Celeste style aircraft, please) but inside they are generally a nuisance. Unrealistic people, banana fingers etc. It really doesn't do it for me. However, one of the first things you notice when you squeeze yourself into the reclined seating position of the Discus is your knees. They're there in front of you, and Aerosoft have managed a good rendition of this. As you would expect, the legs move with the rudder pedals, the hand and right arm move with the stick. In fact, the only disappointing aspect of the person is that he keeps his left hand firmly on his knee while the spoiler lever moves back and forth to your command. If you really don't like the character, you can get rid of him by clicking on the buckle of the harness, but I tried it once and have to admit that this is the first aircraft I have flown in which I feel the figure is almost a necessity. I can also tell you that this pilot is of a nervous disposition – Using TrackIR to get closer and see the modelling of the hands, he has quite clearly been biting his nails!

The instrumentation will probably seem sparse to those who have never flown a glider, but what is there is really all that you need. It is worth noting beforehand that the instruments will change their values (metric/imperial) according to the unit of measure chosen within your FSX settings. I'll start with the pure glider, which is the basis of all three variants, and discuss the additional engine controls later. Only two instruments (okay, three if you include the GPS) are common to all aircraft – the ASI and the altimeter. They are fairly standard, but the gauges are clean, crisp and easy to read. The third (and only other) circular gauge is the variometer, which indicates whether you are in rising or sinking air. It reads in the same manner as a vertical speed indicator, so again it is fairly straightforward. You will probably notice the lack of artificial horizon, turn and slip indicator – completely unnecessary for a glider but the extremely complex replacement for these is there – a bit of string taped to the canopy. The primary instrument for any glider, and it works perfectly, right down to the loose end constantly flicking back and forth. For those unfamiliar with the yawstring, imagine it as an arrow, with the bottom end as the point; the foot it points to is the one you need to push down on the rudder pedals to remove any yaw that has developed (you aim to keep the string centralised vertically on the canopy). In the simulation, as in real life, it is directly affected by (and responds to) the airflow around the aircraft. And when we get onto the soaring section later, hopefully you'll begin to see why it is so important that it has been modelled correctly.

Other than that, there is a small radio on the central pillar directly in front of the control column, and the C4 Competition computer. Sounds like I dropped that in as an afterthought? Don't believe it – it really does take this aircraft from gameplay to simulation. According to the developers, it is 98% true to life, only omitting the settings menu (which, though sounding rather important, would actually be of virtually no use within FSX). I'll not attempt to describe the numerous functions which are controlled by just the three switches on the gauge – for a detailed understanding of this instrument and to get the most out of it, you must read the manual. This is the actual real-world manual, and you should be prepared to print out all 22 pages so that you can reference it in flight if you are to get the most out of this simulation. So what does the computer do, in simple terms? Well, the clue is in the name – Competition. The Discus is a regular competitor in the Standard Class events of gliding competitions, which generally take place over courses of varying distance comprising a start line, intermediate waypoints and a finish line (usually in the same location as the start line). The C4 works in conjunction with the GPS to get you from waypoint to waypoint in the most efficient manner. It will give you a target speed to fly, the glide path and distance to your next waypoint, will calculate the wind and many other variables which will affect the way you fly your route.

The Discus BT has additional controls for its engine – a pair of switches on the instrument panel, a lever on the left side of the cockpit and a placard to explain how to start the engine (it's worth reading the placards, as they are a handy reference to save you digging out the manual).

The BM model has a much larger instrument for control of the engine, but again its use is straightforward. There are also controls associated with the running of the engine around the cockpit of the BM.


This, to me, was going to be the make-or-break section of the package. So much is communicated to you aurally when gliding that it quite simply had to be right. Okay, you can have all your fancy instruments, it looks right and it feels right. But unless you have all those little sounds telling you what's going on it doesn't really feel right. You may think that it's quite easy to get the sounds right for a glider, because there's no engine to worry about (okay, some of these have engines. Point taken, but follow me on this). The thing is, engines tend to drown out a lot of the sounds which let you know what your aircraft is doing. In a pure glider, sounds are constantly telling you what is happening from your airspeed to your coordination. Undercarriage up or down, airbrakes not fully closed? You'll tell by the slight rumbling. And this is one area where I found myself saying “well, I bet it won't . . . okay, wrong again”. The DV panel, when open, lets you hear the air across it. And it sounds right, but I was not expecting the air scoop within the DV panel to chill the back of my neck. Part of the initial instruction on gliders involves having one or more of your instruments blanked off (generally by a bit of card, nothing technical here). The idea is to prove that you can fly if the instrument fails, and when it happens you become acutely aware of all those sounds which you previously took for granted (but which your brain was actually processing). It is surprisingly easy in real life, once you accept what your ears are telling you, and this is echoed with the sound package here. Airspeed can be approximated by the position of the instrument coaming in relation to the horizon, along with the sound of the air around the glider. Too slow and it goes quiet. Too much yaw and it gets rather noisy. If you pull too hard into a loop, you'll hear the fibreglass complaining. And that's really what the sound package is about here – it's not just a set of great sounds that suit the aircraft, you really can fly this glider accurately just by accepting what your ears are telling you.

If you are not used to gliders, the one sound which you may not expect is the audible tone when on the ground, which increases in pitch and becomes a beeping noise as you climb. This is the audible version of the variometer on your instrument panel. Its importance will (like the yawstring) become a bit more clear in the section on soaring later on.

The Add-ons

There are three add-on packages recommended for the Discus: WinchX! Which is already included, and the freeware programs CumulusX! And 'Throttle to Spoiler'.

To take the last of these first, it is a simple dll file which (as the name suggests) converts your throttle action so that it controls the airbrakes. It works perfectly (effectively an on/off option in the modules section), and makes controlling the Discus in the circuit much simpler, giving fully variable control over the airbrakes. There are only two (fairly common sense) warnings with this program; be aware on the BM models that the throttle will then have to be controlled by using the mouse in the VC and, and when changing aircraft to a powered aircraft remember to reset the value so that it controls the throttle. As full forward represents closed spoiler, you may find yourself at full throttle otherwise!

WinchX! is included as part of the Discus package – after the Discus has installed, a new installer will automatically pop up for this program. I've only had six winch launches in real life, so am not really in a position to judge this program fairly but it does seem to capture the rapid progression from ground level to altitude well. It is fully controllable, the straightforward control screen allowing you to adjust the significant parameters. Also, there is the likelihood of a cable break if you are too harsh on the controls, or if you try to take a Discus full of water on the lightest cable. It is a very impressive program, also available as freeware for personal use, by Peter Lόrkens.

And so to the third add-on, again by Peter Lόrkens, and early versions are freeware (though the latest requires purchase of a license). CumulusX! is not a part of the Discus package, but to get the most out of the aircraft you need something to keep it in the air. And FSX is not going to help you much there, so if you want to progress to flights of a decent duration, this is the add-on you need. Earlier versions needed SimProbe to interface with FSX, but the later ones do it all by themselves. It provides both thermals and ridge lift according to where you are and what terrain is under you. Now I don't want to mislead you here – I had some problems getting it up and running. Probably a lot of it was down to the usual 'bloke syndrome' (what's a manual?) but when I got it running well it was a revelation. There are two things that help you set it up properly; a manual and a very good support forum in the 'Soar' section of the Aerosoft forums. Peter
 willingly gives his time to help people with various problems, and is usually able to get things up and running. Once again, it is possible to download as a freeware package and the support from its developer rivals that of some payware!

So what can you expect from CumulusX! when it is running? In terms of thermals, you will see clouds created which are quite distinct from standard FSX clouds, and act as a guide to finding thermals. According to how you have set the program up, lift will be generated but beware that around the column of rising air there is falling air, which you must fly through first. You are able to set many variables through the small interface (lift ceiling, strength, diameter of the thermal etc) under the Tools – Configuration heading. Play around with it, it's worth spending the time.

Ridge lift is created by reading the terrain under you during your flight, so if you are flying along (for example) the Cotswold Edge and the wind conditions are correct you will find lift all the way along it. More than anything else, what this program does is create a living, moving sky around you, with lift and sink according to the time, season, weather and the terrain underneath you.

Peter Lόrkens is developing his tools for FSX further. However, it is possible that some upcoming developments may require registration for a small fee. If you are at all serious about gliding in FSX, you should visit his website at


Get used to using the rudder, that's my first piece of advice. This is not an F16, it has long wings with ailerons outboard so adverse yaw is present in bucketloads. For a first flight, I'd recommend those with no previous gliding experience just to aim for a successful circuit. Okay, it sounds simple, but you've only got one shot at the landing so make sure you get it right all the way round!

Removing water (which is set to full by default) is also handy to get the feel of the Discus initially: when you come to add water later on, you'll appreciate how much heavier and slower the responses are in the sim.

Let's assume you're using the winch to get you airborne: Push over towards the top of the climb before using the yellow handle to the left of the stick to release the winch – if you're still nose-high you will stall almost immediately. Once you're off the winch, you'll want to play with the handling – it's smooth fibreglass hull enables you to build up speed fairly quickly in a dive so peg it back to about 70kts and get used to that adverse yaw. The rudder is your friend. Now bring the speed back, no spoilers here just raise the nose a bit. Once you get into the stall regime (around the 50kias mark) you'll notice the aircraft starts to wallow and you need to be accurate with your rudder here to prevent a spin or a spiral dive. Notice how it's all gone quiet, except for the low tone of the audible variometer which tells you you're sinking. At this point, as mentioned, you need to be accurate with your rudder – so what happens if you're not? Well, the stall and spin are modelled accurately and you will need to apply the standard recovery techniques. You'll lose altitude quickly and (as mentioned previously) speed will build up rapidly once stabilised so back on the stick and it's about time to join the circuit. Heights we're looking for here are 600 to 800ft joining downwind, 400ft turning base and 200ft onto finals (though as you get more used to it these heights can be decreased slightly). A general rule of thumb here is to keep your wingtip over the runway on downwind and you should be in about the right place! Use the airbrakes carefully around the circuit to keep your speed at stall+10kts, any sign of wallowing you need to push the stick forwards. Remember for the landing that you're aiming to put it down on the main wheel, with the tail bumper only inches above the ground. Tail-first landings in real life can damage the airframe, so rounding out too much is to be avoided. A few flights like that, and you should be comfortable enough to try something a bit more adventurous. So let's see how this Discus package performs around a 50km triangle:

The route I've set up is from Bidford Gliding Centre, and because FSX insists that your flight plan has seperate departure and arrival points it terminates at Long Marston (only a couple of minutes glide away from Bidford). I've manually edited the route so that there is a turning point at Wellesbourne Mountford (the airfield itself) and another at the village of Kineton (near Edgehill, and Shenington gliding club). The first thing to remember is that CumulusX produces thermals according to the ambient conditions so I've chosen an early afternoon in July, which should give a fairly decent chance of completing the course!

With the flight loaded up, it's worth taking a few minutes over the pre-flight – it's only a short course I'm flying here, so I'll leave the C4 set to show me my deviation from track. With the GPS giving me a rough idea of my location along the route, the C4 will give me a precise bearing to fly to get me to my next waypoint. Check over the instruments, make sure the levers are where they should be (gear, trim, airbrakes). Then have a look out to see if clouds are being formed by CumulusX! (pics 0 and 1). It's quite easy to differentiate them from FSX standard clouds – the nice dark underside and (from the air) the shadows cast on the ground. Once they're formed, it's time to do your last couple of checks (canopy closed and locked, airbrakes closed and flush, wheelbrake released) and start up WinchX! I had a very good start to the flight, with a thermal forming over the airfield and one not too far away, so was able to get a good initial climb in. As you can see in pic 3, my airspeed is about 57 kts, the yawstring is central and the aircraft is moderately banked – the instrument panel coaming provides a good reference point to the horizon to maintain both bank angle and speed (remember what I said earlier about not using your instruments much? I'm using audible vario to centre myself in the thermal, yawstring for co-ordination, sounds and instrument coaming to judge airspeed) In the real thing, you need to be looking out of the canopy because you could have over twenty gliders in the same thermal as you – opposite, above, below, and each with different thermalling characteristics so constantly changing position in relation to you. And we're going up like a rocket. Having found such a good thermal to start with, it makes sense to stick with it until just below cloud base before heading out to the first turn point. Pic 4 shows the starting point of Bidford, with the shadow cast by a CumulusX! cloud to the top of the picture. Okay, so off we go towards Wellesbourne, in as straight a line as we can – use the C4 to keep us on track, and trim the aircraft nose down a bit to build up speed between climbing points. But it's not a case of sit back and relax at this time, you're still keeping an eye out for other aircraft and managing the aircraft's energy. With reference to the varios, I'm altering my speed along this leg – pulling up into any lift (slowing the glider so that we spend longer in the rising air) and then pushing forward to build the speed when in still or sinking air. By using this method rather than turning constantly in thermals, I've still got good altitude as we hit the first waypoint and our time along the route is good.

Making sure we pass Wellesbourne on the outside of our triangle (pic 6), it's off towards the village of Kineton. I'm expecting to look for a thermal on this leg, gain a bit of height to make sure I'm not left too low too far from our airfield. Recognising the old RAF base at Gaydon just off the nose (pic 7), it's comforting to pull up into a good thermal over the airfield (pic 8). The Discus' predictable thermalling characteristics show themselves well here: I pull the nose up and go into a steeper turn than earlier, playing a bit with the rudder to keep the yawstring centralised all the way around but the aircraft feels steady. The turn can be easily slackened or tightened as required to maintain position around the core of the thermal, and four turns later we're nearly at the cloudbase again.

Around the outside of Kineton (pic 9) and it's off towards Bidford on the longest leg of the triangle. With the height in hand, it's time to push the nose forwards and build the speed (pic 10). At higher speed, you have to work a bit harder to keep the wings level and the yawstring centred (as you'll have seen from the pictures so far, CumulusX has built a fair amount of lift and the sky actually feels alive, with air rising and sinking all around you). We pass Wellesbourne for the 2nd time (this time on the other side, pic 11) and overhead Long Marston (pic 12) which you will remember is the destination of our flightplan. Scanning ahead, you can see Bidford just under the yawstring (pic 13) about 4km away and push the nose even further forward to begin our final glide (pic 14). As the speed builds towards our maximum, you will need to be careful – pull too hard and you'll overstress the glider This is also the time to dump any water you may be carrying (lever on right side of cockpit), which means you'll also be adjusting stick pressure as the Discus gets lighter. A gentle pull on the stick at this speed will give you enough height for a circuit, but your speed will decay quickly so make sure your turns are well co-ordinated!

So how did it feel afterwards? Good, I have to say. It's a vast improvement on the gliding we've been able to do up to now in FSX. It actually makes you work at it – The Discus is not overly simple to fly, but once you learn its characteristics you will have a vehicle with which you can comfortably set yourself challenges. By the same token, when you put it all together and are successful at whatever you set yourself, you really feel a sense of achievement. The demonstration flight above is 63km in total, the Discus is designed for much more than that. I'm actually thinking of trying out a 300K in the near future


Well, how does it stand up in comparison to Condor – that's the real point here. Actually, I was pleasantly surprised. I expected to finish by saying that, although it's a good package, Condor still has the edge as a gliding simulator. But I'm not so sure now. Because the Discus itself is a gem, but it's only one glider – Condor has lots, but not to the same standard. And that's Condor's aiming point – it gives you a choice of glider and is intended for multiplayer competition flights. But as I hope to have conveyed, with this package you can get the same experience of flying a glider around a competition track, with all the usual refinements we're used to in FSX, over recognisable scenery which you can use for navigation. As for choice of gliders, I happen to know that (now the Discus is finished) there's a Nimbus in the works! I haven't tried the FSX multiplayer function yet with the Discus, but I will. And I really mean that comment at the end of the 'soaring' section – the one thing it has left me with is the desire to go back and do it again over a longer distance. To go gliding in FSX instead of Condor.

For more information on the Discus Glider X, visit the product page at the Aerosoft web site or simMarket.

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Paul Frimston learned to glide whilst working at Bidford Gliding Centre in the 1990s. He has also been fortunate enough to log hours on a range of interesting aircraft, from the J3 cub up to the DC3. But he still wants to fly a jet! He found MSFS during the early days of FS98, and has been hooked ever since. Currently working on the railway, his spare time is taken up Beta testing and looking after his family and their ever-expanding family of pets.

Nick Churchill has been providing images for marketing purposes of Flight Simulator products for several years and claims that staring at a virtual cockpit for too long can make you go blind.