RCdad,

Here are some quick charts laid out for stopwatch checking of trap speeds. You need a lot of room to get up to speed and then hit your marks, but if you are good on the watch buttons, you should come close enough. The longer you can make your trap, the more accurate your speeds will be.

dist time fps mph
90 1.00 90.00 61.36
90 1.20 75.00 51.14
90 1.30 69.23 47.20
90 1.40 64.29 43.83
90 1.50 60.00 40.91
90 1.60 56.25 38.35
90 1.70 52.94 36.10
90 1.80 50.00 34.09
90 1.90 47.37 32.30
90 2.00 45.00 30.68

dist time fps mph
130 1.50 86.67 59.09
130 1.60 81.25 55.40
130 1.70 76.47 52.14
130 1.80 72.22 49.24
130 1.90 68.42 46.65
130 2.00 65.00 44.32
130 2.10 61.90 42.21
130 2.20 59.09 40.29
130 2.30 56.52 38.54
130 2.40 54.17 36.93
130 2.50 52.00 35.45

Here's the Excel formula I used to figure this:

=1/((5280/fps)/3600)