XLSM file extension is an Excel Macro-Enabled Workbook file. Therefore you may need to enable the macro to be run on this particular spreadsheet.
If you have 2003 or below excel, you may download the compatibility pack via this link,
http://www.microsoft.com/download/en...aylang=en&id=3
The macro in this file is a set of instructions which I wrote for executing the SOLVER function to iterate each individual element (20 of them) variables for induced velocities in axial and radial directions.
In simple term, it is not a simple closed form calculation i.e. executing a direct function such as y = 3x, where you just plug in x value, you’ll get y value. No it is not the case here…
The solution require a few guessed values, calculate and check the result against pre-set conditions, if okay – stop, if not okay – re-insert a new values, re-calculate, re-check and so on and so forth until all the values inserted satisfy all the set conditions. Off course these loop processes can be done manually, but it’ll take ages to get it done. Therefore we leave it to the computer to do this task as it never complain as long as it has the electrical power to run… hehehehe… This is where the SOLVER plug-in for excel is required. And that is why also I cannot upload XLS file format alone, because it won’t work!
You may load the solver plug-in via these instructions from Microsoft,
http://office.microsoft.com/en-us/ex...001127725.aspx
I may write the codes using matlab, but not everyone have access to it, but with excel I think great many people will have it in their PC.
With regards to the drag, we deal only with the induced drag on the propeller blades that is trying to slow down the rotation of the propeller itself. If you are referring to the post made by Aerosplat, all he did was run the prop at an rpm, measured the static thrust via either a spring scale or a calibrated weight. The output here will not depends on aircraft drag what so ever. And that is what our goal here, to simulate actual thrust available when you run a propeller.
The final aircraft movement forward however will depend not only on the available thrust but the aircraft aerodynamic drag as well. And determination of aircraft drag is whole new subject altogether. Maybe if time permit, I’ll deal with it…
But on the surface, let us say your aircraft weighs 12lb and if the available thrust is 14lb, when the aircraft is statically vertical, it may hover forever because the available thrust is more than the weight that is pulling the airplane down. In this scenario, the aerodynamic drag of the airplane doesn’t play any role in pulling down the airplane.
When you are flying straight and level, the speed of the airplane is limited to the speed of air being dump rearwards. The different of speed between the air being dump to the back and the forward speed of the airplane is the actual thrust available. If at that moment there are no accelerations (i.e. your airplane is flying at constant speed) then those available thrust are equivalent to the airplane drag. As you accelerate the airplane, the different in speed drew closer and closer resulting in your available thrust drew lower and lower until it reach an equilibrium state once again.