Automission - Constant Speed

Hello everyone

Have anyone tried to do an automission achieving perfectly constant speed starting from the first waypoint after takeoff to the last waypoint just before landing?
Could you please guide me where to read about this? I think this related to inner control loop performance but ill appreciate if someone can guide me that who already tried to do it before.

Thank you!

if anyone can help will be great! since i am planning for a flight this week