Jwenting From Netherlands, joined Apr 2001, 10213 posts, RR: 17
Reply 1, posted (12 years 11 months 6 days 2 hours ago) and read 7230 times:
Check the manual or keyboard config for which keys to use. I have them mapped to a switch on my yoke for easier use.
Trimming makes sure the aircraft maintains a constant pitch attitude (or yaw in the case of rudder trim), makes it possible to fly the aircraft without constantly applying pressure on the controls (if properly trimmed, which isn't always possible in FS due to the discontinuous nature of the trim command in FS).