So I doubt that a plane that took very obvious inspiration from a certain european fighter and was remarkably rugged (with its wings tested to 15G equivalent, surviving that with little damage, at which point they stopped testing and moved on) would somehow have both a lower IAS and mach limits.
Static load test does not reflect aeroelastic nor compressibility effect, which is a common since, also “14G” was an optimistic number for ultimate load factor ( real structure failure beyond this limit), without considering real air load and buffet that will encounter in actual flight. That is a consensus in aircraft design. The compressibility effect itself has little to do with the structure, its more of an aerodynamic stuff, and a flutter induced by compressibility has to do with the natural frequency of the structure, it was never to be that you build a plane more rugged and it will dive faster, the aircraft design wasn’t that simple. A rugged aircraft could still meet an early separation of the airflow and been thrown into an uncontrolled compressibility dive.
Here you mentioned the BF-109 dive limit in game to be 790kph, that is a very good example of such “manual + margin” policy. The bf109 has similar airfoil as ki-61, but shorter wing span, smaller ailerons, thus has a faster dive limit than the ki-61. The manual of bf109 limits its dive at 750kph IAS, thus Gaijin gives it 790 with 40kph margin. Although there were a lot of testimonies claimed bf109 experienced dive as fast as 900kph. Again that don’t count, since the pitot static system error in compressibility dive.
Unless the rivet counters haven’t gotten to the P-47 and called them unbalanced, the Ki-61 is quite a ways behind it in mach limit. In fact, you’d have to go all the way down to the Wildcat to find a M0.75 limit, with all the other single engine fighters that come after it being able to go at least past M0.8.
The P-47 was designed to have large dive speed with its Seversky airfoil, and incorporated many compressibility dive tests, later on equipped with recovery flap to obtain a such hight dive speed. Another example would be the F6F-5 in game ,which was limited only with 803kph in a dive, which was slower than ki-61. While in reality its dive limit was 440 knots IAS and some testimonies said it dove at 870kph, the Ki-61 pilots in Kanto air battle found their dive speed couldn’t match the Hellcat.
三式戦
イ旋回性能我と概ね同等若しくは敌やや优る。我が高度差１５００ｍ付近より突进せば、敌の旋回回避により射距离内に入りたるときは追随困难なること多し。
ロ急降下速度は、我よりやや大なり。
The 803kph limit in-game came from the F6F-3’s limit with 415kts due to tail buffeting coupled with natural frequency of the tail. That was another example about dive speed of an aircraft has a very complex nature.
Again, I would say other than this dive limit, ki-61 family was quite accurate in the game. This dive speed issue can be accepted to make Japanese plane in game competitive, but I have to say the reality would be less optimistic.
