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.
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:
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:
1st Wind Layer – at ground level (11 knots with mild turbulence and only slightly gusts from the SE):
2nd Wind layer – at mid ridge slope (strengthening with light turbulence and slight gusts, veering more southerly):
3rd Wind Layer – above the mountain tops (Stronger wind, smoother with no gusts and veering more southerly):
1st Cloud Layer:
2nd Cloud Layer:
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.