Related to this post is a YouTube video featuring one my virtual cross-country soaring tasks in the Aerosoft Discus X. The video can be accessed at the end of this post.
This is the third cross-country flight in a series of test flights using real-world weather add-ons for FSX. This series of flights explores the notion of using a real-world weather add-on to augment the virtual soaring environment provided by CumulusX!. The methodologies I chose to test this notion are not rigorous. The test flights were as much about enjoying a cross country task based on some newly acquired Orbx scenery for Laufenselden airfield as they were about discovering some potential new ways to create a virtual soaring environment. Nevertheless, I am going to take the liberty of drawing some overall conclusions, from the anecdotal evidence acquired in these experimental flights.
In this specific test case I used Active Sky Next (ASN) to capture and save a historical snapshot of ‘real-world weather’ in FSX. To capture the weather snapshot, I waited until the initial weather update had been downloaded and installed into FSX and then I saved the current flight in FSX. I then shutdown the ASN client application to prevent any further weather updates. As demonstrated in my previous YouTube video, periodic weather updates are undesirable when using CumulusX! because some changes in reported weather can remove all CumulusX! thermals in an abrupt and unrealistic way.
I made one slight concession towards the principle of ‘comparing apples with apples’ in that I used the same cross-country task as my previous tests. It is a 63 nm task with three turn points based at Laufenselden in Germany. It was not practical to use the same date and time as any of my previous test flights because ASN did not produce a useful thermal distribution until I selected a new virtual date and time in FSX. In fact, it was difficult to find any dates or times in the ASN historical weather records that would produce a reasonable thermal production from CumulusX!. This issue may turn out to be an ongoing frustration in trying to extract good thermal conditions from ASN. I should point out, however, that I only tried the first few weeks of August, plus I skipped some days and also I chose to rule out any clear sky days because I do not like flying cross-country in conditions that only produce blue thermals. After much trial and error I settled on 12:45 UTC on the 9th August 2014. This weather snapshot produced a promising distribution of CumulusX! clouds around the Laufenselden airfield.
For this test I also set ASN Wind Options for updrafts and downdrafts to zero so that lift and sink would be controlled exclusively by CumulusX!.
So how did it go?
The following Plan-G screen capture shows my flight path overlayed on the task flight plan:
The first leg of this task from Laufenselden to Selters began well. I was even able to stay close to cloudbase by ‘dolphining’ and only stopping to circle in two thermals. As I crossed north of the A3 autobahn at Montabaur, I noticed that the northern region of this task course was devoid of any CumulusX! clouds for as far as I could see. Moreover, as I progressed further northward, a patchy stratus cloud layer began to replace the abundant cumulus layer, although some cloud textures looked more like stratocumulus. CumulusX! will not produce thermals where a stratus cloud layer is dominant. CumulusX! will not even produce blue thermals in these conditions. Faced with this desperate situation I chose to fly at a very conservative (slow) speed to maintain glide efficiency and I abandoned any hope of a more direct route to Weilburg by backtracking to the south after passing the first turn point. This strategy gave me a reasonable potential to find some thermals and avoid a land-out. After backtracking to the south-east, the first cloud I tried was a dud, but I quickly found another and managed to claw my way back up to cloud base. I was then able to proceed eastwards until within reach of the second turn point. At that point I wasted a lot of time climbing as high as I could in a mediocre thermal before making a dash for the Weilburg turn point. Having reached Weilburg with sufficient height, I was then able to return safely to the thermal producing region on my south west track towards Diez.
The necessity of the off-course diversions (zigzags) to intercept thermals in the last two legs of this task are debatable. Nevertheless, I arrived at the finish line with just enough height to make a slightly truncated left hand circuit and land safely at the airfield.
You might be tempted to think that I should be dismayed by the uneven thermal distribution around this task. To my mind, however, that is precisely what made this task challenging and thus more interesting, even realistic by real-world standards. Nevertheless, CumulusX! still appears to be rather too pedantic about eliminating all thermals under a broken stratus cloud layer – a few blue thermals in those conditions might be more realistic.
The weather transitions were relatively smooth and realistic compared to any weather variability achievable with default FSX weather. The light and fluky wind variation in the saved weather snapshot was well controlled and convincing. I was surprised that this variable wind appeared to be maintained even though I had shut down the ASN client application. Thus I wonder if the ASN server component is still active in circumstances like this? Moreover, this rather nice feature of the ASN weather snapshot was evident even if after I re-booted the PC and re-started FSX with the saved flight. So far I am impressed!
On the other hand, I suffered much frustration in trying to find a date and time that would result in reasonable thermalling weather from ASN with CumulusX!. The problem here could be twofold: firstly the cloud reporting might be inaccurate or limited in the weather information resources used by Active Sky Next and secondly CumuluSX! has an extreme aversion to any dominant stratus cloud layer, even in areas where that cloud layer is not overcast. In contrast to ASN, the FS Global Real Weather add-on has an option to give preference to cumulus clouds and thus is a better option for working with CumulusX!, even though the weather transitions are less well controlled.
In an overall sense, CumulusX! is a fabulous FSX add-on for virtual soaring enthusiasts but it is a pity that its absolute aversion to any dominant stratus cloud layer could not be watered down a little or even made tunable in the configuration settings. Then we could better utilize the outstanding weather control of the Active Sky Next weather engine to provide some more challenging and realistic cross-country soaring tasks.