100mph horizontal does surprise me. I would be interested in seeing your math, pm it to me if you don't mind.
A330 length: 58m
radius of spin circle: 29m
circumference: 2piR (pi =~ 3.14etc) =~ 2 * 3.14 * 29 = 182.12 m
182.12/4 (a 'complete' spin each 4s) = 45.53m/s (the tail is running along the path of the circumference)
45.53m/s = 45.53m * 3600/h =~ 164km/h
aprox. 100mph
