140MPH on just 4S! It's really fast!
Took out my Arx to test out the GPS on it. Turns out I still need to improve it's angle to get better reception, so for top speed I defaulted back to the old standby of distance / time. The road I'm on has telephone poles spaced 75m apart, or about 250ft. Counting frames from my Fatshark goggles which record at 29.90 FPS (what a weird FPS!); I was able to determine my top speed was very close to 140MPH. I then backed it up with a 132MPH pass on the same battery. Just out having high speed fun, not trying to set any records or anything.
Check out https://rotorbuilds.com/build/13171 for more info on the designers build.
Frame from https://quadstardrones.com/