Category Archives: X-Plane

X-Plane 11: Racing the sun at Cunderdin WA

After lengthy delays with some technical and personal health issues, I finally…finally managed to get this latest X-Plane 11 cross-country gliding adventure recorded and edited!

I even managed, after several failed attempts, to eventually upload all two hours of it to YouTube, although I had to split the video into two parts.  Such is the nature of the 2nd rate internet services that we are lumbered with in Australia.

Apart from having some more fun with another virtual gliding adventure in X-Plane 11, my task was intended to be an experiment. My question I wanted to be answered by this task was this:

Can this simulator successfully and convincingly implement a cross-country gliding task of about two hours duration, which is based solely on ‘blue’ (cloudless) thermals?

To answer that, here are the links to the videos on my YouTube channel, and my conclusions and X-Plane 11 settings can be found below.

MY CONCLUSIONS

This was overall another enjoyable flight adventure using X-Plane 11, and that was in spite of some personal pain discomfort at times during the flight. X-Plane continues to surprise and please me with what it can provide to a virtual gliding enthusiast like myself, and it does this regardless of some pretty significant limitations in the modelling of a realistic soaring environment. For example, there are no cloud based thermals in X-Plane. Every glider soaring session in X-Plane 11 is effectively what glider pilots call a “blue” thermal day.  Imagine what a great virtual gliding sim this would be if X-Plane had competition soaring environment functionality similar to that provided by the CumulusX! add-on for FSX.  Blue thermal days are fine occasionally,  and they do occur sometimes in the real-world, but thermals with cumulus clouds on top make for a more tactical cross-country challenge or glider race. Completing a cross-country task without a land-out is less of a lottery with cloud based thermals.

THERMAL LIFT MODELLING

One good thing I can say about the X-Plane 11 thermals is that do appear to be modelled reasonably realistically in terms of their lateral structure. The thermals exhibit a noticeably irregular lift profile when circling in them, making centring on the core quite challenging. I liked this and believe it is much better than the thermals in FSX and Prepar3D, which are too circular in lateral profile. With the weather settings that I used, the X-Plane thermals seemed lumpy and bumpy  – just like the real-world thermals as I remember them.  Also, the lift at the tops of the thermals tapers off reasonably convincingly in X-Plane, but I am still uncertain about whether there is any modelling of the overall vertical lift profile for X-Plane thermals.

There is still some more testing to be done. Some questions about thermal modelling remain in doubt or are still unanswered by just one test task. These include:

Do the thermals exhibit lift weakening close to ground level?

Do the thermals widen and lift become stronger in the upper levels?

Are the life cycles of thermals modelled in any way?

THERMAL LEAN/DRIFT

One tick in the box for X-Plane 11 that I can report is that an examination of my flight tracks when circling in thermals indicates that X-Plane seems to be making some attempt to model either thermal lean or drift of thermals in response to the wind.

EFFECT OF GROUND FEATURES & LAND CLASSES

On the other hand, I have not seen any clear evidence yet that X-Plane 11 thermals might be linked to ground features, nor have I seen confirmation yet that the thermal distribution might be linked to land classes such as large water bodies, forests, built up areas etc.  The land class question might be resolved definitively when I fly future tasks in more diverse areas than was the case at Cunderdin.

CLOUD FLICKER

One current disappointment is that the X-Plane 11 cloud shadows exhibit a very annoying and distracting flicker on my system, which I cannot seem to get rid of. To get around this problem for this task, I eliminated the lower cloud covering, leaving only the high cirrus layer. The cloud shadows from the cirrus layer still flicker but are less noticeable due to the lighter shading from these high level and thinner clouds.  Since recording this flight, I have found a plugin that allows me to make all cloud shadows totally transparent, effectively hiding cloud shadows, so that this problem does not irritate me. Nevertheless, I would like to have visible cloud shadows that do not flicker – so I am still looking for a better solution to this problem.

THE FLIGHT PLAN

The flight plan is a 160 kilometre triangle based on a real-world task at Cunderdin in Western Australia. The original task was flown by Luke Dodd in an Astir CS sailplane in 2000. For my own convenience, I chose not to convert the task turn point coordinates, and instead, I modified the turn points slightly, placing them over the grain elevator structures at Kellerberrin and Wyalkatchem. Also I placed the start and finish lines over the glider clubhouse at Cunderdin airfield with an arbitrary maximum start height of 6,000 feet MSL and a minimum safe finish height of 500 feet AGL.  My chosen start and finish line height limits are typical of the limits set for UK Virtual Gliding Association tasks.

The Plan-G flight planner shows that I should be able to complete the task in under two hours if I can achieve a task average speed of 83 kph or better. As the 2-part video above shows, I completed the task faster than that and was able to land and park the glider before the sun set.

Flight Plan

Flight Plan (click to enlarge)

 

AIRFIELD LAUNCH POINT LOCATION FOR THIS TASK

For this task, I setup for an aerotow launch from Cunderdin, Western Australia on runway 32 at 15:50 local time on a sunny autumn (fall) afternoon. My intention was to release at 3,000 feet AGL, climb to the maximum start height of 6,000 feet before crossing the start line, hopefully by about 16:00. This would give me about two and quarter hours to complete the task before the sun sets. I felt that this would give some incentive to keep pushing harder, in effect a race against the sun, rather than having me taking it too cautiously and cruising around the course at the best L/D speed.

Airfield

Airfield (click to enlarge)

 

DATE AND TIME SETTING

Time and Date

Time and Date (click to enlarge)

 

WEATHER AND THERMAL SETTINGS

Atmospheric Conditions

Atmospheric Conditions (click to enlarge)

Cloud Layer 1

Cloud Layer 1 (click to enlarge)

Wind layer 1

Wind layer 1 (click to enlarge)

Wind layer 2

Wind layer 2 (click to enlarge)

 

Wind Layer 3

Wind Layer 3 (click to enlarge)

Connecting XCSoar to X-Plane 11 from a networked PC

 

I had a request in a comment on my previous post asking me to describe how I connect XCSoar to X-Plane from a networked PC. The following method is the one that I use, but there is at least one other way to do this using a freeware serial port emulation product called “HW VSP”. I have not tried the freeware option myself.   If you want to use the freeware “HW VSP” for virtual ports emulation then I suggest that you join the UK Virtual Gliding Association (also free) and ask for help on their forum. I believe that some of the UKVGA members use “HW VSP”.

I use the product called Virtual Serial Ports Emulator (VSPE) by Eterlogic.com. You have to purchase a license to use it on 64 bit MS Windows.   I believe it is free on 32 bit MS Windows. Because I am running it on two 64 bit PCs, I bought two licenses but I am not sure if that is necessary or not. I have used it successfully on both a wired LAN and WIFI.  There may be a simpler way to do this, but this works and I have not bothered to try any other methods.

1. Install VSPE on X-Plane 11 PC and configure as follows:

Create a COM1 Connector device using default settings (this is the port that we will send X-Plane GPS output to). If COM1 is already in use on your system, you can use a different COM number.

Create a Splitter device with COM5 as the virtual serial port and COM1 as the Data source serial port. This will connect the X-Plane GPS output via COM1 to the TCP network server created in the next step.

Create a TcpServer device with Local TCP port 5555 and Source serial port is COM5. This virtual device will send the serial data stream received from the Splitter across the network to any TcpClients created with VSPE.

Save the configuration.  To re-load a saved configuration, you may have to stop the emulation first.

Click on the green start icon below the menu bar to start the emulation. Below is a screenshot of how it should look when you have started the emulation. NOTE: The emulation probably needs to be started before X-Plane  (it definitely does for FSX).

VSPE on X-Plane PC

I set this configuration up years ago, so I am not sure, but I believe that I used default settings for the VSPE emulation devices.  I provide screen captures of my settings in VSPE just in case I am wrong:

X-Plane PC COM1 properties:

X-Plane COM1 port properties

X-Plane PC Splitter properties:

X-Plane Splitter properties

X-Plane PC Splitter settings:

X-Plane Splitter settings

X-Plane PC TCP Server properties:

X-Plane tcp server properties

X-Plane PC TCP Server settings:

X-Plane tcp server settings

 

2. Install VSPE on networked PC with XCSoar installed and configure VSPE as follows:

Create a COM2 Connector device using default settings. This is the port that that XCSoar will read the GPS serial data stream sent from your X-Plane PC.

Created a Splitter device with COM5 as the virtual serial port and COM2 as the Data source serial port. This will get the serial data stream from the TCP Client device created in the next step and output it via COM2.

Create a TcpClient device with Remote TCP port 5555, The Remote TCP host  is the IP address of your X-Plane PC.  The Source serial port is COM5. This virtual device will receive the serial data stream across the network from the specified VSPE server PC.

Save the configuration.  To re-load a saved configuration, you may have to stop the emulation first.

Below is a screenshot of how it should look when configured.  Click on the green start icon below the menu bar to start the emulation.

With VSPE emulations running on both the server and client PCs and a successful network connection the status for each emulation device should change to “OK”.

NOTE: You may need to open port 5555 through your firewall on both the server and client PCs for the VSPEmulator.exe application.

VSPE on XCSoar PC

XCSoar PC COM2 properties:

XCSoar COM2 properties

XCSoar PC Splitter properties:

XCSoar Splitter properties

XCSoar PC Splitter settings:

XCSoar Splitter settings

XCSoar TCP Client properties:

XCSoar tcp client properties

XCSoar TCP Client settings:

XCSoar tcp client settings

 

3. Start X-Plane 11 Go to Settings –> GPSHardware

Enable the moving map/NMEA COM port and set COM1 with 5 NMEA transmissions per second. You can experiment with the transmissions per second, but 5 per second seems to work OK for me.  (click on image to view larger size)

EDIT: I have carried out some testing of the transmission rate since this post and found that values less than 4 per second or greater than 5 per second impact frame rates and cause stutters.  So on my system, 4 to 5 per second works best.

X-Plane 11 GPS output setting

 

4. Start XCSoar on the networked PC.  Double click on map display to open menu buttons. Click on Config menu button, select Devices button and configure Device A to COM2 with Baud rate of 4800. The serial driver is optional, but I use the Condor Soaring Simulator driver, which seems to work OK.  There are an extensive range of drivers available in XCSoar. (click on image to view larger size)

XCSOAR Device config

My First Cross-country Gliding Adventure in X-Plane 11

I have been a strong critic of X-Plane, particularly when used as a virtual gliding simulator.  So when X-Plane 11 was recently released, I jumped right in with the default X-Plane glider, the Schleicher ASK21, fully expecting to be disappointed in the usual way. I decided to attempt  to complete a ridge soaring task, rather than using short ad hoc flights to test the soaring environment and flight modelling.  This cross-country flight test surprised me greatly. In spite of the obvious flaws in the X-Plane soaring environment, I was able to complete this task and, in fact,  I found the experience to be both entertaining and enjoyable.

Here is my full flight YouTube video:

When you compare X-Plane with default FSX as a virtual gliding simulator, neither provides a convincing virtual soaring environment. However, the availability of the CumulusX! competition soaring environment add-on for FSX makes a huge difference.  Moreover, there are a lot more 3rd party glider models available for FSX.  Until, X-Plane or a 3rd party developer can provide a competition (multi-player) soaring environment similar to, or better than, CumulusX!, FSX will remain as my preferred virtual gliding simulator. Nevertheless, I have been inspired by my first cross country adventure in X_Plane 11 to try some more test flights, and possibly some more full cross-country adventures, in X-Plane.

So let us now have a look at this specific cross-country adventure, which has changed my view, at least to some extent, about using X-Plane for any virtual soaring.   Firstly I will describe the task design and then the custom X-Plane weather settings. This will be followed by some discussion of issues that were noticed during the flight and my conclusions.

 

Task Design

I chose Zell am See in Austria as my launching site.  In X-Plane 11, the longest grass strip at Zell am See is 08L, so that seemed to be the best choice for my glider operations. However, I was later to learn that 08L no longer exists in the real world, which might explain why X-Plane has two roads running across the runway.

This is the flight plan created in Plan-G:

Flight Plan 2017-04-22_17-56-28 2

Capture

I put the start line on the ridge of hills running north from the airfield (TP SCM – Schmittenhoehe) and the finish line on the ridge of hills running towards the airfield from the east (TP HHN – Hahneck Kogel.)  The maximum start height was set at 6000 feet above mean sea level and the minimum safe finish height was set at 300 feet AGL above the finish line.

Local Sim Date and Time for this Task:

July 17, 14:02 local time

 

X-Plane Custom Weather Settings

Atmospheric Conditions and Thermals:

Capture 2

 

1st Wind Layer – at ground level (11 knots with mild turbulence and only slightly gusts from the SE):

Capture 3

 

2nd Wind layer – at mid ridge slope (strengthening with light turbulence and slight gusts, veering more southerly):

Capture 4

 

3rd Wind Layer – above the mountain tops (Stronger wind, smoother with no gusts and veering more southerly):

Capture 5

 

1st Cloud Layer:

Capture 6

 

2nd Cloud Layer:

Capture 7

 

X-Plane 11 Observations and Conclusions

Following are some issues that I noticed with X-Plane 11, but please note that I have very little experience with X-Plane in general and also bear in mind my previous comment that this cross-country glider flight was an enjoyable and entertaining flight regardless of these issues.  I may also draw some comparisons with Microsoft Flight Simulator X, although I do concede that these comparisons are somewhat unfair given that I have a number of add-ons in FSX that improve the virtual gliding experience greatly.

When I start a flight with the ASK 21 glider in X-Plane, it defaults to an aerotow and begins to launch immediately.  This is a bit of nuisance.  I haven’t worked out yet how to start a gliding flight with the wheel brake on, which might prevent an immediate launch. I would prefer to start the flight stationary and parked and then manually choose with keyboard or controller buttons whether to take an aero tow or a winch launch.

The aero tow ground roll seemed far too short to me, plus the tow plane got out of alignment with the runway as soon as it started moving – perhaps because it is susceptible to cross wind.

A nice feature in X-Plane is that tow plane can be manually steered left, right or straight ahead in flight, however, the turn rate is quite slow and does not appear to be adjustable.  This limitation may be a problem in some terrain situations. The CumulusX! smart tow option in FSX does not have this feature although it does allow you to pre-select either a left hand or right hand turn out after lift off.  I prefer the X-Plane feature.

There are two variometers in the X-Plane 11 ASK 21, which is not uncommon in gliders. It has an analogue vario and an electronic vario with a switch to enable the audio feedback.  The two vario needles appear to be in lockstep, so I assume they are both indicating the same thing. The analogue vario is calibrated in metres per second but the electronic vario only has tick marks.  The analogue vario looks very much like a standard “Winter” model Total Energy vario but it appears to react more like a Netto vario.  This is contrary to what is written in the X-Plane manual. The electronic vario audio feedback appears to have three distinct tones – a warble, a constant tone and a series of beeps.  The X-Plane manual says that the beeps indicate that glider is in an updraft and that the constant tone tells you that you are sinking but that does not correspond with my experience on this flight.  It appears to me that the frequency of beeps is a representation of the Total Energy input to the glider in the form of height gain and the constant tone pitch seems to be linked to the Netto vario  positive deflection representing the amount of lift in the surrounding airmass – in other words the constant tone appears to indicate that you are in an updraft and this is also contrary to what is stated in the X-Plane manual.  I haven’t worked out what the intermittent warble represents yet – it might be a glitch in the feedback sound. Even though the X-Plane variometer audio feedback is quite different to what I am most familiar with in some real-world gliders and in FSX, it is nevertheless quite useful once you get used to it and allows you to respond quickly to variations in lift while keeping your eyes outside the cockpit.

The ridge lift appears to be a tad erratic in X-Plane – certainly it is harder to predict than in FSX using the CumulusX! plugin.  The lift doesn’t appear to strengthen in indents in the ridge where the wind should get compressed and thus increase in speed and I haven’t noticed any decrease in lift at the base of ridges. Also I have not been able to detect the typical sweet spot of maximum lift slightly to windward of the ridge tops.  As I have no real-world experience with ridge soaring, I cannot say for sure that X-Plane ridge lift is not realistic – it just isn’t as convincing to me personally as it is with FSX + CumulusX!. Maybe I need to increase the wind speed a bit to get better and more consistent ridge  lift in X-Plane.   I have noticed that lee side effects such as excessive sink and wind rotor are either not modeled in X-Plane or at best are very weakly modeled.

The thermals in X-Plane are what we know as blue thermals – that is they are not associated with cumulus clouds. Nor are they associated with ground features as far as I can tell.  I recall hearing someone say that flying cross-country in blue thermals is a bit like a blind person stumbling across the countryside hoping to bump into to trees to climb.  Unfortunately, there is no 3rd party plugin that I know of to provide cloud based thermals in the same way CumulusX! does for FSX.

The in-flight sound effects  of the ASK 21 is reasonably convincing but it doesn’t include any variation for the airbrakes (spoilers) being deployed. Moreover, the spoiler deployment should be linked to the wheel brake on the ASK 21, which it isn’t in X-Plane.

The modelling of adverse yaw effect for the X-Plane ASK 21 seemed to be hardly detectable.   I don’t believe this is realistic for a glider.

The ground roll sound sound effects and landing tyre squeal are not realistic in my opinion.

I encountered two major pauses of the simulator during this flight but that could be my system or my X-Plane setup – further investigation required.

The lighting and scenery in this mountain area around Zell am See were very impressive in X-Plane 11, with the exception of the roads.  Also the default X-Plane 11 mesh looked rather crudely triangulated compared to what I am used to seeing in FSX with enhanced add-on mesh.

I encountered  one very obvious graphical anomaly in the scenery or mesh on the second leg of this task, and I got a good close-up look at this gap in the scenery in the video.

I managed to bump into a few thermals in this task and tried to stop and circle in one but it was too weak and difficult to center on the core.   Nevertheless, that thermal did appear to me to be quite realistic compared to some real-world thermals, which are often quite lumpy and bumpy and sometimes have multiple cores that are difficult to center on.

In spite of these issues, this was, overall,  a challenging and very enjoyable experience and I am encouraged to try some more X-Plane 11 glider flights in the future.  I may try a ‘flat-lands’ (thermalling) cross-country task next, even though I expect it to be very difficult without cloud based thermals.  Also I plan to repeat the Zell am See cross-country ridge soaring task in FSX as another YouTube video to see how different it will be using the CumulusX! add-on.