- Yes (Overwing Vapor)
- Yes (Volumetric FX improvements)
- Yes (Weather Variation)
- No
I, like many others, was very happy when I heard that wing “vapes” (vapor trails) were being added to the game. It’s a fascinating phenomenon that no game involving fighter jets should be without. The implementation of these effects, however, was in my opinion incomplete. I will break it down in detail below, but the three main areas of improvement that exist (in order of importance) are as follows:
- Lack of Overwing Vapor Effects
- Insufficient Volume of Effects
- Lack of (or at least not enough) Variation by Weather
For an extremely brief summary, all three of these condensation phenomena are caused by the adiabatic cooling of air as its pressure decreases. This cooling in turn causes the relative humidity of the air to decrease, as the water capacity of air lessens proportionally with temperature.
As the air decreases in pressure and cools further, the relative humidity reaches 100%. This is known as “saturation”, and means the air cannot hold anymore water. But, the water does not just disappear. Instead it gathers around tiny particles in the air in visible, but tiny, water droplets that collectively become visible to the naked eye.
This process is what forms clouds in the sky, rising air expands, lowers in pressure, cools, and eventually reaches saturation. Air rising, however, is not the only way that air lowers in pressure and condenses. Among many ways, an airfoil (wing) creates lift through creating a pressure difference between both sides (top and bottom) of the wing. This creates a low pressure area of air (a “wake”) on the top of the wing. This pressure difference (in most scenarios) is not enough to form clouds in straight-and-level flight. However, once an aircraft enters a situation where its angle of attack is high, such as slow speed or sharp maneuvers, that high angle of attack can further lower the pressure on top of the wing, and provide the final ‘nudge’ needed for the air to reach saturation and condense.
Vortices (such as those created by leading-edge root extensions (LERX), and the wing at large, forming at the tips) are usually the first condensation phenomena to appear. Centrifugal forces involved in the spinning motion of a vortex keep air away from the center, naturally forming an area of low pressure. LERX purposefully create vortices to keep airflow attached to the wing (delaying the stall) and the pressure differences across the wing that create lift create vortices at the tips of the wing as air flows down the wing and toward the end where the high and low pressure air mix, creating vorticular motion.
As mentioned earlier, if AOA is increased further, an aircraft’s wing wake will drop even further in pressure. The turbulent flow “wake” any object creates is directly porportional to its size, and as a wing’s AOA increases, the amount of air that it blocks (its “size” relative to the slipstream) increases, and the area of turbulent flow it creates becomes larger. This can lead, eventually, to the formation of overwing condensation. Overwing condensation happens when the wing’s entire wake lowers in pressure enough to cause condensation. Because of this, overwing condensation happens across the entire wing.
This is an effect that, unfortunately, is not present in War Thunder. Adding it to the game would enhance realism in the sense that in certain conditions you could use these effects to ascertain your enemy’s speed state, as well as the intensity of their maneuver. Plus, they add a lot of screenshot value to dogfights.
This next problem is another which I think is extremely important, mostly from a graphical standpoint. To be blunt, the LERX effects we have in game do not possess enough volume and opacity. In fact, in some situations, they are practically see-through. Below are some examples.
F/A-18E in the shade. The effects from this angle leave some to be desired, but really are not that bad.
Here are the effects in the sun. They are practically see-through.
Now, here is a shot from real life.
As you can see, these vortices modeled realistically should be pretty much opaque, only gaining some translucency as they start to dissipate. I would also like to point out the general lack of “cloudiness” of these effects. They don’t really give off the effect of being cloud condensation. I believe they could make these effects more convincing by:
- Give the in game effects a more uneven uneven, billowy, and random texture reminiscent of real clouds
- Give the in-game effects random “flashes” where they disappear and reappear for milliseconds at random intervals, This gives the effect of turbulence in the flow causing condensation to rapidly disappear and reappear.
- Make them larger, these vortexes can create quite large clouds, and emulating this in game would go a long way to sell the effect. The F-16 is probably the plane that needs this the most.
I think Battlefield 6’s effects provide a good benchmark for the quality of vapor FX that this game should strive for. Take a look at this video (not mine) for a good demonstration. You’ll see buffed-up LERX effects, both in size and in quality, and overwing vapor.
Finally, there is the point of weather. I am not sure if relative humidity/dewpoint are modeled in this game, but they should be, at least arbitrarily, to allow for different weather conditions to affect the level of vapors seen in the game. If the water content in the atmosphere is high, then vapor will form more easily on aircraft wings. This is something that I think is less important, but still worth mentioning. Airliners usually don’t get vapor over their wings on a hot, dry, sunny day in Arizona, but on a rainy, muggy, humid day in Florida, something like that may be more likely to occur. Even if it is just modeled in preset levels based on the precipitation/clouds on the map, I think weather should affect the creation of wing vapor at least somewhat.
I sincerely thank anyone who has read to this point. It took me a good amount of thinking to write this post, luckily I am fresh out of an Aviation Weather class, so I had much of these concepts already in my head. Don’t forget to go back up to the top and vote on the poll!
