Airplane that made the most aces

It is a tricky question simply because there are many examples of less than five in one aircraft but five or more in combined.

John Landers got six in P-40s, 4 in P-38 and 4 in P-51. Preddy got his first 3.33 in a P-47, made ace in a P-51B, then ran a total of 23 in the Mustang.

If you look at 8th AF aces, the fighter pilots that flew in the 56, 78, 353 were dominantly P-47 aces
Many of the P-38 pilots that became aces, made ace in the P-51. Many P-47 'partial' aces that switched to P51 in the 4th, 352nd, 355th, 359th and 361st made ace in the Mustang.

All but one of the 355th FG (21) aces became aces in the Mustang, for example. All the 357th FG and 354th FG and most of the 352, 359, 361 and 4 FG aces made ace in the P-51.

So, there are 'combination' aces in which five were not obtained in one a/c (many in 8th AF), there are aces with more than five that had at least five in one a/c, and some very few that were aces in two types of a/c (Goodson - but Not Gentile and Godfrey who each had less than 5 in P-47, but all three got five in Mustang - Herky Green, Vermont Garrison p47/F86, Gabreski P-47/F86, CB Head P-40/P-38, McCorkle Spit/P-51, etc).

To be sure you have to dig in Olynyk's Stars and bars for US aces and Shores Aces High for Commonwealth.

Actually there is a small amount of overlap because some of the records in "Aces High" pertain to US pilots who flew in the RAF and then transferred to the USAAF in 1942. However, the numbers are small.

For my review of "Aces High", I elected to count pilots who had 5 or more kills while flying Spitfires, my rationale being that it constituted being a Spitfire ace rather than an ace who flew Spitfires. It seemed the most logical way to treat a very complex scenario. The number of Commonwealth pilots who got kills in multiple aircraft types is quite staggering - Hurri, Spit, Defiant, P-40, Blenheim, Typhoon, Tempest, Whirlwind, Buffalo, P-36, Gladiator, P-51, P-47, Beaufighter, Mosquito. We flew a lot of different fighter types (although pilots of twins seldom seem to have moved onto single-engine types).