I need to bend some 22mm copper pipe into quite a wide radius curve -
is it possible to use conventional pipe benders to do this (the type
with long handles)?

It's just that from looking at them, they appear to have a fixed radius
former - or is there a way of increasing the radius of the curve you
make?

Above all, I need to produce smooth curves - is there a better way of
doing it?

Any advice would be appreciated...

Nigel Lord