An unofficial speed record, 245 kilometers per hour on a 6S quadcopter.
The test was performed over a distance of 120 metres, trying to keep a consistent altitude.
I'll do my best to answer any questions.
Gear:
Custom 'Project Bones' frame
Emax 2306 2750kv motors
DYS 30 amp 4 in 1 ESC
DAL Cyclone props
Dinogy 1400 6S battery.