If your time and distance is correct you were traveling an average of 163.63 mph over your course. My Dust with a Jett 50 had a best time of one half mile in 10 seconds (straight line) for 180 mph. I used a video flying over a two marks and other methods. There is some room for error because of parallax and other things as your speed and mine seem a little high but who knows for sure.

If you divide your mile, 5280' by 22 sec, you get a distance per sec and an easy way to calculate speed.