Five airborne kills is considered an ACE. This doesn't vary from country to country.
You need 5 Kills that can be verified.
Erich Hartman, flew a Me109 and scored 352 aerial kills during WW2............
Erich Hartmann with 352 kills .
A pilot that scores a least five enemy aircraft kills.
The Red Baron.
Eddy Rickenbacker with 26 kills
Usually five, depending on country.
If you're looking for Americas overall ace of aces, it's Richard Ira Bong of WWII with 40 kills. For World war one it was Eddie Rickenbacker with 26. For Viet Nam it's a tie between Steve Ritchie in the air force and Randy "Duke" Cunningham in the navy with 5 kills. In Korea it was Joseph M. McConell with 16 kills
Eddy Rickenbacker with 26 kills
The highest scoring ace in history with 352 confirmed kills was, Erich Hartmann "The Black Devil" flying the BF-109 in World War II; he was also never shot down during his time in the Luftwaffe.
LTC Billy Bishop