I've got it, I've finally figured it out - like a CSI detective in front of a whiteboard full of lines and squiggles and circled words. First came IL-2 Sturmovik, then came the standalone expansion Forgotten Battles, then came the two further non-standalone expansions Ace Expansion and Pacific Fighters. Now comes another standalone expansion, IL-2 Sturmovik: 1946, named after one of the three campaigns it contains, those being 1946, Sturmoviks over Manchuria and the PE-2 campaign.
Mercifully, IL-2 Sturmovik: 1946 is a single installation which includes everything this series has ever spawned. That means it's upped the aircraft count to over 300, it features hundreds of new missions and a handful of new maps too. The new content includes some of the insane prototypes those Nazis were working on before we stopped them, most notably a bizarre dual-rotary VTOL plane which is pretty much impossible to land once airborne.
Other than the alternative-future Hun-jets, the expansion catalogues a swathe of missions across China.As it stands, it's the only sensible way to purchase IL-2, especially if you're planning on taking it online, as most servers demand at least the first three expansions be installed. It takes a bit of a knock over the steep asking price for what is clearly an ageing title, and the new content is mashed sim-potato for fans, but for a while at least, it'll remain the definitive IL-2 collection.