I just did a quick back-of-the envelope calculation:

Thrust = Drag

Drag = 1/2(rho)V**2SCd - Fortran notation used to denote velocity squared

I assumed air density (rho), surface area (S), and Drag Coefficient (Cd) as constants and arrived at a ratio of (200 mph) squared divided by (170 mph) squared

I also assumed prop efficiency as a constant (probably not the case) and power to thrust curve is linear (a simplification) and came out with 1.38 as the ratio.  Simplified, but a starting point.


Rob