beziercurve profile 6 0 -53 19.8 -5 -63 19.8 -5 -83 19.8 5 -83 19.8 5 -63 19.8 0 -53 19.8 
mkedge profile profile 
wire profile profile 
mkplane profile profile
parabola w 0 0 0 1 0 0 50
mkedge w w -pi*20. pi*20.
wire w w
pipe result w profile

set square 3895.63