Soaring with FSX >>  Aircraft/Gauges >> LS8-18


This complete LS8-18 download includes a new instrument panel (in the LS8-18 created by Wolfgang Piper), installing a new 'LS8-18 B21' glider (that will sit alongside Wolfgang's original LS8-18 if you have that installed). This LS8-18 version replaces all the CAISET DLL instruments, and adding a variety of new instruments to the panel. Particular care has been taken to accurately calibrate the instruments to the LS8-18 polar.

The new instruments are all FSX XML gauges without the need for 'exe' or 'dll' installation (the glider is a simple drag-and-drop into the FSX folder), and the panel includes three variometers, total energy, netto and speed-to-fly.


Wolfgang has produced an excellent glider model, with an accurate polar. The panel extends the instruments as follows:

Plus some other minor instrument improvements. The Netto and Speed-to-fly readings automatically compensate for the ballast currently carried. A new 'trimwizard' is implemented, which sets the trim immediately on the trigger being pulled on the joystick. All instruments correctly switch to other backgrounds and units dependent upon FSX units settings.

The panel instruments

  1. Winter vario displays Total Energy.
  2. 302 slave vario displays Netto.
  3. 302 LCD computer vario displays Speed to Fly and Arrival Height
  4. Airspeed Indicator displays airspeed. (Click gauge for an STF indicator to appear)
  5. GPSNAV displays direction and distance to waypoint.
  6. Moving map displays flightplan on a relief map.
  7. Altimeter displays aircraft altitude.
  8. Ballast indicator displays percent of water ballast carried. (click gauge to display current aircraft weight)
  9. Gear lever displays/controls main gear wheel up/down.
  10. Trim indicator displays trim setting (click joystick trigger to adjust quickly).
  11. Becker radio.

1. Winter Variometer displays Total Energy climb/sink rate

The Winter variometer main needle is displaying Total Energy compensated climb rate. This is simply your actual climb rate (or rate of sink) with small adjustments to compensate for changes in your airspeed which would otherwise affect the reading.

When the pilot chooses to pull up to enter a thermal or to dive to exit a sink area, an uncompensated variometer would include the change in altitude due to the change in velocity in its read-out, thus obscuring the climb or sink rate due to the rising air. Therefore an uncompensated variometer can only accurately indicate the vertical speed of the glider when flying at constant speed. The effect of total energy compensation can easily be seen if you pull up into a climb in still air: an uncompensated vario will show a rapid climb rate, while the TE vario will correctly show you continuing to lose energy.

The indicated climb on an uncompensated vario is particuarly misleading as you pull up into a thermal - at this point the uncompensated vario will indicate a climb whether you're in a thermal or not so it is possible for inexperienced pilots to be turning and cimbing into a thermal that is not actually there. These have been called stick thermals as they are created by the action of the pilot pulling back on the 'stick'.

The action of diving or pulling up affects the speed of the sailplane. A sailplane can exchange height for speed or speed for height, i.e. potential energy for kinetic energy or kinetic energy for potential energy. In fact, in still air, the sum of potential energy and kinetic energy, i.e., the Total Energy, remains constant (neglecting energy loss due to drag), hence the name Total Energy compensation.

Most modern sailplanes are equipped with Total Energy compensated variometers.

The instrument automatically switches between m/s or Knots display depending on your FSX settings.

2. Netto Vario (slaving from the 302 LCD vario)

The needle displays NETTO climb rate (i.e. the vertical movement of the air outside the glider), by subtracting the normal aircraft sink rate from the total energy reading shown on the Winter vario.

The Netto reading is a further refinement upon the Total Energy reading delivered by the Winter variometer. The Netto vario uses the glider airspeed to derive the sink rate the glider should be sinking at in still air at the current airspeed, and subtracts that from the 'total energy' reading. So the reading you're left with should be the net vertical movement of the air outside the glider.

Note that this FSX gauge is performing the same calculation that would be performed in a real glider gauge, using the input pressure sources (i.e. is it not 'cheating' by just reading some FSX vertical air movement variable). This means the gauge performs in the same way as a real gauge, e.g. if you open the airbrakes the gauge will interpret that correctly as unexpected sink. If you leave the wheel down, the netto vario will display sink even in still air, as it can tell the glider isn't flying at it's calibrated sink rate.

If you turn CumulusX off, and select 'clear weather', you'll find the Netto vario reads pretty close to zero throughout the range of normal flying. You'll see momentary dips into apparent sink as you manoever the glider (e.g. a pull-up) as it loses energy during that process. If you do a 'push-over' (i.e. fly as if going over a hump-backed bridge) the netto reading will correctly briefly go positive as the reduced loading on the wings results in temporarily improved efficiency at low speed.

The instrument automatically switches between m/s or Knots display depending on your FSX settings.

3. '302' LCD Variometer / Flight Computer

The main needle displays a Speed-to-fly indication (i.e. the needle moves down, as if indicating sink, to tell you to speed up and vice versa). The top numeric display is the expected arrival height AGL at the next waypoint in the flightplan. The middle numeric display (at 3-o-clock on the instrument) is the Macready setting. The bottom numeric display is the climb average.

Heights are in feet, climb rates in knots, or meters and meters-per-second depending on your FSX units settings.

The four readings (STF, arrival height, maccready, climb average) are explained in more detail below.

302 Needle: Speed-to-fly

Speed-to-fly is yet another derived improvement in variometer compensation...

In this image, the stf needle is indicating lift (as if +3 knots) meaning "you're in lift, slow down". You can see the Netto vario confirms this. At this point it would be reasonable to question the difference between a Netto and a Speed-to-Fly variometer, as they both appear to behave in a similar way (generally, needle up in lift, down in sink). But the difference is probably more marked than the difference between the Netto vario and the Total Energy vario (with a bit of luck you understand that difference). If you think of the Speed-to-Fly instrument as a variometer then the reading starts making sense in that it is taking some of the thinking workload off the pilot by indicating lift only when the you should actually slow down. i.e. pull up i.e. the lift has to be strong enough to exceed the MacCready setting and you have to be flying fast enough that slowing up is sensible. Counter-intuitively, you can fly through a little bit of lift and if you have a higher MacCready setting, and you're not flying fast enough, the STF needle will still indicate sink, i.e. speed up.

Explaining this on paper is a poor substitute for flying with the instrument and getting used to it's behaviour. At first you can just blindly follow its instruction, speeding up or slowing down depending on whether the needle is going down or up. But after a short while you get used to thinking of the instrument just as a particularly intelligent variometer, than doesn't bother you with lift if you're already slow enough.

Given that the variometer is computing the 'Netto' movement of the airmass outside the glider, the vario can compute the optimal speed to be flying through this air. I.e. if you are flying through sink you should fly faster to spend less time in that sinking air, and vice versa for rising air. The faster the air is sinking, the more you should speed up.

The speed-to-fly reading is the delta between the computed optimal speed and the speed you are currently flying, displayed on the normal vario needle. If you are flying at the optimal speed then the needle will show zero. If the needle goes down as if indicating sink, then you should speed up.

A fully ballasted glider should normally be flown fairly fast (e.g. 90 knots) to benefit from all that ballast on board.

If you're flying too slowly (common for inexperienced pilots) then the STF indication will indicate sink i.e. speed up. As you speed up, the needle will return to zero as you reach the 'optimal' speed.

These instruments on the panel have a unique learning aid in the use of the Speed-to-fly indication: if you click the face of the ASI (i.e. airspeed) gauge, the real-time computed speed-to-fly is indicated with a red 'bug' moving around the rim of the ASI gauge. In the image above, the 'stf bug' is drawn on the ASI at about 92 knots. You will see the delta between this bug and the ASI needle is directly translated to the Speed-to-fly needle on the 302 computer vario. Also you can immediately see the effect other variables have upon the computed speed-to-fly, e.g. if you change the MacCready setting the speed-to-fly will change, or if you dump ballast then the speed-to-fly will gradually reduce as the ballast drains out.

Note the instrument has no knowledge of thermals ahead, and the reading does not take into account your 'pucker-factor' based on proximity to the ground, so if you're low and at risk of a landout you should not be charging around at 90 knots regardless of what the STF instrument is telling you to do... in this situation you should simply turn the MacCready down to zero.

302 Digital readout: Arrival Height

The flight computer will attempt to calculate your likely arrival height at the next waypoint. The simulated reading in the FSX LS8-18 computer vario is unusually sophisticated in that it gives you arrival height *AGL* (above ground, at the waypoint).

In this case, the flight computer is suggesting you will arrive at 440 feet above the next waypoint.

The graphic below illustrates a pilot gliding towards a waypoint, with the 302 vario indicating an arrival height of 440 feet (the real Cambridge 302 actually doesn't display arrival height at all, just an altimeter reading)..

The flight computer uses the elevation given in the flightplan (or the next point-of-interest in a mission) for the height of the next waypoint, and arrival heights are displayed relative to this. If you pick an airport as a waypoint in the flight planner then ground elevation is by default put into the flightplan. If you use some other waypoint type in the flightplan (e.g. an Airway Intersection) then the altitude of that waypoint will be embedded in the flightplan and the 'arrival height' computed by the vario will be relative to that. So for normal cross-country soaring purposes you should ensure the heights in the flightplan are ground elevations at each waypoint (or Zero if you'd prefer the arrival height indication to be MSL).

As with the FSX GPS, this indication is meaningless unless you have a sensible flightplan loaded in FSX.

The flight computer has to take into account a variety of factors to come up with a reasonable prediction of your arrival height, assuming a straight glide to the waypoint. These include:

You can view the same 'arrival height' reading either of two ways, which are actually synonymous:

You can use either of these definitions, whichever you're comfortable with.

As a reminder, the 302 flight computer vario is assuming zero overall lift/sink during this glide to the waypoint, that the wind remains constant at its current value (a headwind shown here) and that the pilot flies at a speed as appropriate to the MacCready setting.

More sophisticated flight computers, such as the SDI C4, can actually perform this calculation around multiple waypoints to the final destination, which is fairly complex, whereas the simulated Cambridge 302 shows arrival height at the next waypont only

302 Digital readout: MacCready Setting

The MacCready Setting is the value input by you, telling the vario the expected thermal strengths.

In this case, you have told the flight computer to assume an expected thermal strength of 3 knots.

Note that m/s will be used for this reading (in 0.5m/s increments) if metric settings are chosen in FSX.

The value is adjusted using the knob labelled 'Mc' at 5-o'clock on the LCD vario. Easiest is to hover the mouse over the knob and rotate the mouse wheel. The vario displays the MacCready setting in either m/s or Knots depending on your FSX settings.

In the image above, the pilot has set a conservative MacCready setting and is flying relatively slowly between thermals and conserving height. This means she needs to climb less in thermals, i.e. saves time in thermalling (but is possibly losing time in the cruise).

The pilot in this image has set a higher Macready setting, and is cruising faster between thermals. This means he has to climb more than the pilot that was cruising more slowly. Which pilot achieves the best cross-country speed depends on the strengths of the thermals (i.e. which pilot has guessed correctly in the Macready setting). If the thermals are weak, then the pilot that is cruising more slowly will achieve a higher overall speed because they are spending less time climbing in the weak lift.

In this case, if we see the two flights superimposed, we see the more aggressive flying by the faster pilot has actually paid off, i.e. the thermals are strong enough that his additional height loss and need to climb is outweighed by the increased speed beween thermals.

Essentially the MacCready Setting is the value you use to tell the computer how aggressively (i.e. quickly) you want to fly, and the computer will perform its computations based on this value. For a fully-ballasted LS8-18, a MacCready Setting of 3 knots (1.5m/s) will mean you should be flying at about 90 knots between thermals. The idea is simply the stronger the thermal you expect, the faster you should fly to get there. This is well explained in the "Art of Flying" last video in the sequence on this page.

302 Digital readout: Average Climb Rate

This shows a moving average of total energy climb/sink in either Knots or m/s depending on FSX units settings.

In this case the computer vario is recording an average climb rate of 1.7 knots.

When you are thermalling, this displayed value can guide your judgement on what to set for the Macready setting. Also, if you are thermalling, if this average is below the readings you have typically seen in other thermals on the same flight, then perhaps you should leave the current thermal and find another.

This average will also give you a clue that the thermal strength is weakening near the top of a climb, and you should leave the current thermal rather than milk it to the top.

4. Air Speed Indicator

As seen on all aircraft, the ASI displays airspeed in either Knots or km/h depending on FSX settings.

This instrument in the LS8-18 includes a speed-to-fly training aid made visible by clicking on the face of the dial (seen here at 92 knots). See information above under 'speed-to-fly'.


The GPSNAV shows the direction and distance to the next waypoint in the flightplan. For the GPSNAV to display something sensible, you must have an FSX flightplan loaded. The moving map will display the flightplan.

The GPSNAV is similar to the stock FSX DG808S gpsnav with various improvements made to improve readability. More significantly, the internal 'GPS' engine has been re-written to replace the original programming, so the pilot can step forwards and backwards through ALL the turnpoints in the task by using the 'up' and 'down' buttons.

Details on the home page are as follows:

The distance-to-go units (miles, km) depends on your FSX setting. You can click the 'left' and 'right' buttons on the GPSNAV to see another couple of pages of information (waypoint info) but these are less useful than in the real GPSNAV to make sure you've loaded the right flightplan, because in FSX you can just look at the moving map or use the FSX menu.

The GPSNAV 'page' you see displayed above is the 'Home' page of the GPSNAV, and it the one used for normal flight around a task. Any waypoint of the task can be chosen to be the current 'active' one by using the 'up' and 'down' cursor buttons while on this home screen. To gain familiarity with the instrument, try these buttons while you're still on the ground.

The GPSNAV will automatically select the next waypoint in the current flightplan to be 'active' when you are within 500 meters of the current waypoint. However there is nothing to stop you overriding this behaviour at any time simply by using the 'up' button to move on to the next waypoint. An example of where this might be useful would be in a start of a task, where you know the start line allows you to be a lot further than 500 meters from the start point, but you still want to have the GPSNAV move on to the first TP even though you haven't passed 'through' the start point. Also, many FSX soaring flightplans have the home takeoff airfield as the first waypoint in the flightplan even though it isn't actually the start point of the task, and one click of the 'up' button will put things straight ready for your record-breaking competition flight.

In some circumstances, you may wish to keep the GPSNAV pointing at a waypoint even though you have moved within 500 meters of it and the gauge has clicked over to the next, e.g. you've done a poor start and want to start again. In this case you can simply re-select the start waypoint by using the 'down' arrow. The usage is intuitive and obvious if you just try the 'up' and 'down' buttons.

If you use the 'left' and 'right' arrow buttons, the GPSNAV will cycle through a couple of other 'pages' of information about the current active waypoint. This is only marginally useful in the air, although one page contains the elevation of the active waypoint (labelled 'EL:') and this is useful to check the 'arrival height' being presented by the 302 LCD computer as this arrival height value is above this elevation given for the waypoint. Normally the elevation for the waypoint will be the ground elevation, so the 302 arrival height reading will be what is commonly referred to as 'AGL' (above ground level).

6. Moving Map GPS

The 'Moving Map' GPS is fairly obvious and has very limited function - all you can do is zoom in/out using the +/- buttons. The map displays the flightplan and actually I find it easier to navigate to the next waypoint by ensuring the flightplan track drawn on this instrument is vertical than using the '>>' indications on the GPSNAV.

In the image above, the glider is on track, but heading off-track by about 15 degrees. The active leg of the flightplan (i.e. soaring task) is highlighted in green, the inactive legs red.

The current leg on the flightplan is shown with a green line, the others will be red.

7. Altimeter

This is a standard static-pressure-driven altimeter, that switches units from feet to meters in FSX depending on your FSX units settings.

8. Water Ballast percent full indication

The pair of levers on the starboard cockpit wall are the Ballast Valves. CLICK on the lever to toggle both open/closed. The LS8-18 loads into FSX fully ballasted with water.

The small LCD display on the panel displays percentage of water ballast carried. Broadly, full water ballast increases the weight of the empty glider by 50%. Modern competition gliders carry jettisonable water ballast (in the wings and sometimes in the vertical stabilizer). The extra weight provided by the water ballast is advantageous if the lift is likely to be strong, and may also be used to adjust the glider's center of mass.

The LCD ballast indicator has a configuration aid for FSX to help in transplanting the gauge into another glider. If you click the face of the ballast indicator gauge it will display the current all-up weight of the glider in Kilograms. As you dump ballast you'll see this figure reduce.

Although heavier gliders have a slight disadvantage when climbing in rising air, they achieve a higher speed at any given glide angle. This is an advantage in strong conditions when the gliders spend only little time climbing in thermals. The pilot can jettison the water ballast before it becomes a disadvantage in weaker thermal conditions. Another use of water ballast is to dampen air turbulence such as might be encountered during ridge soaring. To avoid undue stress on the airframe, gliders must jettison any water ballast before landing. (ref wikipedia)

9. Undercarriage (Gear) lever

In FSX the 'G' key will raise the single main wheel, or you can click this lever.

The lever is up when the gear is up.

10. Trim indicator

The GREEN knob on the left side of the panel is TRIM, i.e. the 'neutral' setting of the elevator. 'Trim forward' will bias the glider into more of a nose-down attitude and at a neutral stick position the glider will fly faster, and the reverse for 'trim back'. You adjust trim using the default keys in FSX, worth assigning to buttons on your joystick. In general you 'trim forward' while in cruise between thermals, and 'trim back' when you pull up and turn into a thermal. The idea is simply to have the glider settle into the appropriate default speed for the situation without you constantly pulling or pushing on the stick.

This LS8-18 includes a TriggerTrim function (as a hidden gauge on the panel) inspired by Peter Luerken's TrimWizard. When you press the trigger on the joystick (i.e. activate the brakes) the trim will immediately move to the position of the stick. I.e. to trim forward, push the stick forward and press the trigger, and you'll see the green indicator move up accordingly.

11. Becker AR4201 Airband Transceiver

This is an airband radio

Test flying the LS8-18 - a tutorial to understand the instruments

Start a flight with the LS8-18 B21, set the weather to 'Clear' and click the 'Disable' lift button in CumulusX. This will make your interpretation of the gauges a little easier.

Take a launch (or slew) to 6000 feet (2000 meters), and settle the glider into a steady glide at 80 knots (150 km/h). Don't forget to raise the gear. (but you will...). Now look at the variometers in the top row of your panel (ignore the readings in the picture above for this tutorial).

First of all look at the top-left 'Winter' vario, which will be indicating about 2 knots down (1 m/s), so the glider if flying with a glide ratio somewhere around 40:1 (80 knots forwards, 2 knots down). If you fly faster, this vario will indicate increased sink, and if you slow down a bit it will indicate a reduced sink rate. This is a direct illustration of the glider 'polar curve' in the diagram above. Note that as you pull the stick back from 80 knots (150km/h) and put the glider into a gentle climb (the altimeter will show the slight increase in altitude), this vario will still show sink. I.e. it is recognising that you are decelerating as you climb, so the overall effect is still as if you are sinking through the air. This is the 'total energy compensation' discussed earlier. At a steady flight speed the compensation is zero so the instrument shows your true rate of descent through the air.

If you look at the top-middle 'NETTO' variometer you will see the needle hovers around zero thoughout your acceleration and deceleration of the glider, with minor fluctuations as you manoever (assuming you still have FSX weather clear and CumulusX lift disabled). This instrument is using an in-built definition of the glider polar sink curve (i.e. the sink of the glider at various speeds in still air) and discounting that from the total energy reading of the 'Winter' vario on the left. So overall this variometer is calculating and displaying what it thinks the outside air around the glider is doing. If you make the glider less efficient, e.g. put the wheel down or open the airbrakes, then the total energy vario will correctly show an increased sink rate and this netto vario will interpret that as sinking air outside the glider and so the netto reading will show this sink. Assuming you are flying efficiently, this vario will give you the clearest picture of the strength of the thermal or sink you are flying through.

The top-right LCD computer/variometer is displaying what is called 'speed-to-fly' on its needle. For tutorial purposes you can be helped to interpret this reading by first clicking on the face of the airspeed indicator. This will cause a red 'bug' to appear on the rim of the air speed indicator (ASI) showing the speed the computer vario thinks you should be flying given the current MacCready setting and airmass movement. By default, the MacCready setting will be 3 knots (1.5 m/s) and as we have the FSX weather set to clear, and CumulusX disabled, then there will be no lift/sink and the computer vario will compute a speed-to-fly of about 90 knots (170km/h). If you are still flying smoothly at 80 knots as at the beginning, then the variometer needle indicates sink (you're not flying fast enough). If you speed up then the ASI needle will approach the currently recommended speed-to-fly (as represented by the red 'bug') and the computer vario needle will go to zero. Congratulations, you are now flying at the recommended 'speed-to-fly'. Note that the computer vario is not directly displaying the speed you should fly at, just a movement of the needle suggesting you are too fast or too slow. It's still called a 'speed-to-fly' reading even though the indication is translated to apparent lift or sink. Confusing at first but it quickly makes sense. You'll find you can swing the speed-to-fly needle up and down just by adjusting your speed either side of the actually recommended speed-to-fly indicated by the red bug on the ASI. Real instruments don't have this 'red bug' so the learning process is a little longer.

Now you can experiment with things that affect the calculated recommended speed-to-fly...


3D glider, cockpit model and flight model by Wolfgang Piper.

FSX XML instruments by Ian Forster-Lewis.