Time taken to turn through n degrees
= (n x 2 pi x TAS)/(360 x g x tan AOB)
Careful with the units; if you use miles per minute, g = 19.065 nautical miles/min/min
At 60 KTAS and 20 deg AOB, 360 deg will be achieved in 54.3 sec; this equates to 6.63 deg per sec.