just don't get me wrong. i personally do not car much about all this measuring stuff. however i am not fully dumb
i understand how gps and other stuff works in principle. nevertheless some people say that radar guns have big difficulties to measure such small things like a rc car. that may include the police radar gun.
and for the gps. suppose the gps system receives new data every 5sec. with 80mph you go for around 180m in 5sec. but as you don't know exactly when those 5sec start you need to go at least say 10 sec full speed to be sure you include a full correct interval to measure. the rc car does nearly 400m in this time frame. thats a freakin long distance do control an rc car going that fast. even if you stand perfectly in the middle of the distance 200m each side. 200m is hard to see and control your car even if you have a very good radio that may do it and the eyes of an eagle. second problem seems to be that there are many interferences the closer you come to the surface. very near to the surface the interferences are getting bigger because of obstacles standing in the way of those satelites being far away and quite flate over the horizon. the probability of an interuption of your satelite interconnection rises closer to the ground. if the interconnection is interupted for a short time you need to go even for a longer time full speed. there are also local differences in the reliability of gps signals.
even if the system gets data in a shorter time interval there are still some sources of innaccuracy that you can hardly control.
but there may be places and gps systems that exclude most if not all of those problems and the measurement is perfectly correct.
so i only wanted to point out that there MAY be some difficulties and failures with the measuring of the speed of rc cars.
the most realiable thing would probably be a light barrier system.
i don't want to question anybodies measurements. i just have some doubts sometimes when i see all those crazy speed readings. i mean in general not the specific one above. my feeling is most rc cars are much slower in reality than it seems when you just look at them.
bye
rhylsadar