I've incorporated the Flak illumination mod (as offered a some time back by Mike) in my effects pack already from the start. I just found a logic error I had introduced in the code while I was incorporating further refinements. One would probably not notice the deficiency right away, perhaps not at all, but I feel much better for having fixed it.
With this flak lighting addition to Explosions.class, I did a few things differently. One is to not have the small calibre stuff (in the Zenitka folders "Germ_20mm" and USSR_25mm") induce any lighting at all. The main reason is that even when setting the intensity quite low and making it effective over a short distance, bursts in or even near clouds cause the clouds to light up like a crazy lightning thunderstorm. And I mean the entire cloud texture element, even if very large. (If the lighting could be confined locally, to just the part of the texture near the light source, that might be OK.) And so it's only the bigger flak for which I've made the illumination active. Another change is to keep the illumination more restricted, so that the landscape/waterscape below, and the clouds above, should not be illuminated to a degree that's horrible.
Here's a couple of perspectives of a nearby burst (the flash texture and the illumination last only 0.06 seconds), from the outside of the plane and inside. It's really neat to see the flashing going on while flying through a dense barrage!