There are a couple of books where he can get the info he needs.

Model Aircraft Aerodynamics by Martin Simons. Mine is the 4th edition and may still be published.

Aircraft Propeller Design by Fred E. Weick has been out of print for decades but still considered a valuable source. It is usually very expensive if you can find a used copy.

There are some simple formulas used to calculate efficiency. Basically, you are measuring the velocity of air produced through the propeller disk due to Bernoulli's theory. The difference in pressure causes air to rush towards the propeller. This is the first type of air velocity (V). Static thrust only gives you half the data. The air causes the propeller to move forward. Airspeed is the second type of velocity (v).