bubbers44:
My trusty 727 did great arcs at 250 knots using heading select. I didn't know I just had to find the LNAV and VNAV buttons. Actually most of the time I rolled into about an 8 degree bank so the bank never changed.
You must have had a lot better autopilot than we had on our 727s. Heading select for us would command a 25 degree bank for any significant heading change.
Having said that anyone proficient in a 727 should be able to fly a DME arc with the autopilot and FD turned off.