Here is the full list of all 12 Rally Copters achievements.
Complete all phase 3 levels with the Mosquito
Unlock all helicopters
Complete all levels
Get a platinum medal
Complete a flag run without taking damage
Perform a successful flipdodge
Travel 100 meters in a single dive
Earn a gold-plus or better medal
Complete a phase 3 level, with no guiding line, in one try
Reach 50 tries in a level
Crash your helicopter after crossing a finish line
Obtain a full landing bonus