The J2M was designed as an interceptor, and the early models had a lot of problems. The early engines were unreliable, and the undercarriage was fragile and often got damaged by the high landing speed of the Jack. It also developed a bit of a reputation as an "ensign killer" due to the relatively high number of accidents with new pilots. It wasn't until the J2M5 that they really had the problems with the engine and the undercarriage ironed out.
The Jack has a higher ceiling and is a bit faster than the George, but has a much shorter range and is less maneuverable. It was put to work intercepting Bombers since so few Japanese aircraft could catch the B-29s, but that didn't mean that it was useless against fighters...
Quick quote from "Aces of the Rising Sun" -
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Akamatsu's fighting ability reached legendary status with his handling of the J2M Raiden fighter... In an astonishing display of aerobatics and raw courage, Akamatsu proved the the Raiden could break a Mustang when, on 19 April 1945, the 34 year old "Raiden Master" flew his Jack against P-51s of the 45 F.S. - fighting on his own terms. he forced his opponents down to low altitude and claimed two or three shot down.
On 29 May, near Yokohama, the 'old man' of the Atsugi Air Corps singlehandedly attacked 75 Mustangs in a Zero and shot down 2nd. Lt. Rufus Moore, again of the 45th F.S. Capt Todd Moore, who witnessed Akamatsu's attack said later "If he had been an American, he would have been awarded the Congressional Medal of Honor".
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Think of the Jack as the 109K4 of Japanese fighters - it might not be as manueverable as some, but that doesn't mean it can't kill you if it is handled right. Until recently, I would've said that it wouldn't get much use in AH, where all the battles are down low. Nowadays, I see such an increase in people staying up high and dropping down to cherry pick kills, I have to say I wouldn't mind seeing another high-altitude ride added to the planeset.
EagleDNY
$.02