CumulusX! does not always play nicely with real-world weather updates

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.

As a follow up to my previous YouTube video that featured testing of CumulusX! with PILOT’S FS Global Real Weather engine, the logical next thing to do would have been to test CumulusX! in a similar way using Active Sky Next (ASN) to take a real-weather snapshot without any further downloaded updates. But while preparing for that 2nd test flight, I was side tracked by the notion of doing a demonstration flight based on dynamic real-world weather with periodic updates injected from Active Sky Next. This could reaffirm my assertion that CumulusX! does not always play nicely with real-world weather updates, and to be honest I was beginning to doubt that assertion.

So my aircraft model, the Aerosoft Discus X, and my flight plan were identical to those used for my previous YouTube flight. The virtual date is also the same as my previous flight, 1st August 2014, but in this demonstration flight I am injecting historical real-world weather with 5 minute updates from Active Sky Next.

Now before we get to the conclusions from this flight, let me emphasize that I like CumulusX! and I like Active Sky Next – they are both excellent add-ons. However in my experience, they do not work well when used together unless I disable the weather updates from Active Sky Next. Likewise for for any other add-on weather engines that take regular weather updates from their servers.

This flight started out well enough with the tug taking me to a weak blue thermal at 2000 ft AGL. The sky looked quite promising ahead on my task course at first, so I went for the start line early. Normally I would climb to cloud base first. However, my confidence was soon undone when a weather update clobbered all of my CumulusX! thermals and left me essentially in a thermal desert. There were some weak patches of lift and sink remaining, which I assume were coming from ASN although they could also have been air texture created by CumulusX! (I have flown test flights with ASN active and CumulusX! disabled, which produced weak patches of lift and sink like this.) Initially I was expecting a thermal population to be re-generated by CumulusX! but my hopes were soon dashed when the FSX cumulus clouds faded away to become a layer of broken stratus. CumulusX! will not produce thermals, not even blue thermals, in these circumstances even though there may be substantial breaks in the stratus layer to allow warming sunlight through.

So is it possible to get around a 63 nm task like this one in spite of the vulnerability of CumulusX! thermals to changing conditions?

The main aim of this demonstration flight was not to answer that question. I designed this task scenario to show the inadvisability of allowing periodic downloaded weather updates when using CumulusX!. Obviously, in the case of historical weather, it should be possible to choose a day on which the weather changes will not impact CumulusX! significantly, but that would be a rather tedious task to check all of the pending updates. Also a more skilled and experienced cross-country virtual pilot would likely make better strategic decisions than I did and thus might complete the task as implemented in spite of the challenges.

This demonstration flight reinforces my assertion that CumulusX! does not always play nicely with regular downloaded weather updates. Disabling downloaded updates is advisable if you want to enjoy some of the nice features of weather engines like Active Sky Next without disrupting the soaring environment. The possibility of a workaround exists if the weather engine has a feature that would coerce the cloud coverage data to always include a useful cumulus layer. I believe that FS Global Real Weather has a configuration feature like that, but to my mind such a feature defeats the original intention of using realistic weather.

So why is real-world weather desirable for virtual cross-country tasks? Why not just stick to creating manual weather using FSX Advanced settings, as the club I belong to does quite successfully for multiplayer events?

Some virtual cross-country tasks are based on real-world competition events and it would be nice to fly these on the day and in the conditions close to those experienced in the real-world. Moreover, recent advances in weather engines like Active Sky Next can provide more realistic and smoothly controlled variability in wind and also smoother transitions for general weather variation based on location and/or time than can be achieved in the default FSX weather. It has been a constant irritation to virtual cross-country task designers that FSX tends to create very abrupt and unrealistic weather variations forcing designers to configure overly static weather conditions. So for me there is a strong incentive to make use of the newer weather engine add-ons for some virtual soaring tasks even though these payware add-ons are unlikely to ever be practical for multiplayer events, particularly those MP events implemented on servers like VATSIM or FSCloud.

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