Aces of the Luftwaffe Squadron

To level up your skills, I recommend getting medals at level 5-1 on Extreme difficulty. For a run that lasts an average of 3 minutes 25 seconds, you will receive from 1200 to 1600 medals (subject to completing the accompanying task, which is elementary in this mission and is always completed (shoot down 125 opponents)). It took me about 4-5 hours of farming after finishing the game at this level. I used an epic plane that has +80% to lives and -40% damage from collisions.