I had the flaps fail on me in a 172 a few weeks ago at night. I fly out of a 2,500 foot field. My friend insisted that i make the approach at 70 KIAS with a slip, although i thought a lower approach speed would have been fine. It all worked out but when i got home I couldn't find a no flaps approach speed in the POH.
So if Vso * 1.3 = Vref (43*1.3=56 KIAS)
Then does Vs1 * 1.3 = Vref (no flaps) (50*1.3=65 KIAS)