How to realistically model propeller static thrust? I am graphing static thrust vs prop diameter for a 600 kW motor and a prop diameter up to 5 m. I have seen the post 'What is the equation for calculating static thrust?' and using its formula and fixed prop efficiency I get a pretty linear graph. At 5 m the thrust is 19 kN.

Structural factors become increasingly important at larger diameters, but what other aerodynamic factors (perhaps prop efficiency changes with diameter) need to be considered to make the graph more realistic?

Update - I assume the prop pitch can adjust to maximize static thrust, but the twist is optimized for high speed (200mph) flight. The engines full power is also available at the best speed for the size of prop being tested. This Equation to bind velocity, thrust and power simplified by assuming unitary engine efficiency is the same as what I have been using.

$$T_0 = \sqrt[\LARGE{3\:}]{P^2\cdot\eta_{Prop}^2\cdot\pi\cdot \frac{d_P^2}{2}\cdot\rho}$$
This basically depends on the prop loading and RPM. If you are not satisfied with the momentum disk theory based results then the next step would be to use blade element theory based calculation.

If I were you I would certainly run few test cases with a known propeller geometry by scaling the propeller. One of the easiest way I can think of doing this is to use QPROP from Prof. Mark Drela at MIT. This is a free software and on top of this it is a command line program which is very well suited for this kind of an activity because all the parameters could be changed on the go, preferably via a bash or python script. 

HTH