They all are Fruda as we got them from a company that does these recordings. I can't remember the website off hand right now as I am on my laptop and sitting in temp. lodging as I am out-processing the Air Force right now and all my stuff is on a truck heading back home. If Dogg pops in here he will be able to tell you.
I downloaded the pack, and it's got some nice stuff. But I will give some constructive criticism.
The Wildcat(s) and Corsairs have the same engine sounds, and the P-47s have totally different ones. The Wildcats had a 14-cylinder engine, whereas the Corsairs and Thunderbolts had an 18-cylinder engine (they both had the same engine, but with slightly different gearings, and in the Tunderbolt's case, a bit more power output).
The P-51s and Spitfires have different engine sounds. Why? And all of the Spitfire models, save for the XIV, have the same engine sound. The reality is that the XX and 60-series engines sounded quite a bit different from each other, and several YouTube videos (among other sources) attest to this.
The P-40s and Yaks should have the same engine sounds. The VK-105 was pretty much an Allison V-1710, though it was just a
bit smaller. Since the engines were/are so similar, many restored Yaks are outfitted with Allisons, and the difference in sound between the two engines is pretty much zilch.
The Wildcats and Lavochkins should have the same engine sounds, as the Shvetsov 14-cylinder engine was a license-built version of the Twin Wasp. And also note that you should copy the engine sounds from the C-47 and paste them into the Wildcats and Lavochkins, as those are real Twin Wasp recordings. I know that sound anywhere. As for the sounds that are in the Wildcat and Corsair folders already, they sound much more like R-2600s than R-2800s.
The 109s have some off-ish engine sounds. For instance, the default Eng file is a recording from Checkflight Gustav, and while that source is
very good (I use it myself), you took it from a point where the landing gear were being raised, thus that whistle-like sound (it's more of a squeak/squeal, really), and not only that, it's at just over half throttle. Eng_1 is similar in that it's not a recording of a full-throttle engine, though it's clear of the background noise. Eng1 is unnecessary, as it's just a clone of Eng_1. Eng2 was recorded at an even lower RPM level than Eng1/_1. Eng3 is a composite of a Merlin XX and some kind of engine howl effect.
The B-17 was done an injustice with its engine sounds, I feel. Like most other packs, this one also uses engine recordings that were done when all four engines were running, which makes an atrocious effect on AHII, since each engine uses the Eng file. What happens is the signal is amplified four times (though about times two as far as overall volume goes), and the mix is muddied and muffled as a result. What needs to be done is quite simple. You need one
good source file recorded from a single engine running at full throttle (Wright R-1820, a full soundset that I happen to have), and it must be normalised at 50% volume (75% for twin engine aircraft). Startup and Shutdown sounds must be done the exact same way, or you'll have a wonky-sounding bomber. Once you've got your bomber sounds setup like this, you'll really fall in love with them all over again... It's a totally different experience when it sounds
right, rather than just better than the default sounds.
I hope you don't take any of this too harshly, but I really do feel that it's necessary to help
all of our content creators do the best job they possibly can, and we won't ever have that quality of work on a community-wide scale if people never criticise anybody's work. Criticism is necessary for the evolution of content creation, for the evolution of the game itself. My dream is to one day have an all-encompassing, robust, authentic sound set for the game, but we really have to work at it and push ourselves to do better than we think we can. It requires hours of work, but in the end, everybody gets a package that improves the experience by leaps and bounds.