Edited sentence: Germany has the highest scoring aces due to often superior aircraft, many pilots having a lot of experience from earlier fighting, and the fact that German pilots had to serve until they were shot down.Most American pilots were cycled stateside to instruct newer pilots after a tour of duty, thus the lower number of kills.Russian pilots had a hard time surviving long enough to become aces, as they often received little training, fought against more experienced Nazi pilots, and had planes that favored a skilled pilot rather than a beginner