First, congrates for the success in installing the required add-in for excel to operate the solver function.

About the aircraft drag, it has nothing to do with actual thrust available from the engine - this holds true. Every action there is an equal and opposite reactions. Just think for while, if we have a thrust of say 14lb, if we need to mount this engine on a table, at a minimum we need to have the engine mountings able to resist 14lb of force pulling it apart.

Now for the same engine, if we were to mount it on an airplane, the pulling force received by the firewall will be at least 14lb also. Now if somehow we manage to deflect the total mass airflow forward of the prop disk, then what we are actually doing is reversing the thrust. Under this condition, the engine mount will receive pushing force instead of pulling!

Most of the time, the nose of the airplane does deflect the airflow slightly outwards, however for any typical aircraft the deflection amount doesn't cause the airflow to reverse in direction, therefore the mass amount of air still being dump towards the rear of the prop disk. Looking at this, we know that in order to balance the momentum of the airflow, the airplane firewall will 'feel' the pulling force...

So be it on a test bench or on an airplane, the nett thrust produced by a propeller(same pitch + same rpm + same ambient condition) remain constant unless we can deflect it until the direction of the airflow moves towards the front of the prop disk.

Okay back to this file. With ref to "2. Tip chord would depend upon the tip end shape, right? So how so you take those various measurements?" a very good question posted by ggraham500, i figure it is good if user only need to insert the prop diameter, pitch and rpm without having to worry about the root chord and tip chord.

So the solution is, based on a typical propeller that i have, i took the plan form coordinates, graphed it out. Equate those coordinates on a 4th order polynomials (curve fitting process), and end up with a written function of chord dimension at a given radius. Using this function, each element average chord can be determined with ease therefore more precise than initially modeled straight taper from root to tip.

The setback... as the plan form area of the simulated prop matches the real thing, the solution will over-predict the thrust produced say around 7 to 10%. The reason for this is simple, in real life, there is a point on the propeller blade that does not produce any thrust at all. The point is the tip of the blade itself. The higher pressure region at lower part of the tip will try to balance itself out to the top surface of the tip. This balancing act causing the tip to loose its thrust. We call this phenomena "tip losses". And because of this also, a shrouded prop will be better in terms of its efficiency.

To overcome this over prediction, Prandtl did suggest tip loss correction factor by modelling it as a vortex element. At this moment however, i leave it out first. Okay enough said, for those who would like to have this modified spreadsheet kindly download here, http://www.mae.my/download/ThrustEstimator2.xlsm

Thanks