I got some pylons around 3 meters high and it is similar to redbull airrace where you fly between those pylons.
The time gets measured when you enter the circuit and when you got out through the same gate. The difference
then is the time you needed for the course.
Now I like to trigger the clock with a light barrier but how can you do that over 3 meters height? Since not
everyone is crossing the two pylons at exact the same height? With laser you would need several at different
height, sonar is probably to slow and wide??? What else exist out there?