Aerodynamics Calculator

Way way back when I first started with FlightGear I found it useful to record information for an aircraft in development.  After some research I decided to use the JSBSIM FDM instead of YASIM.  They both do what they do well, JSBSIM just seemed a better fit for me at the time.  Back to my point.  When creating a model there is a whole bunch of information to record.  For example: aircraft length, wingspan, height, empty weight etc.  It requires a lot of patience and research, but sometimes you just can't find the information you are looking for.  In the JSBSIM manual they suggest using a good paint program and using the pixel locations to make measurements for various purposes.  You have to make a bunch of measurements.  What is my solution you ask?

I made a spreadsheet to help keep it all together.  What I do is get the best to scale and highest resolution 3 view drawings of a plane.  Usually you have some known distances so using the paint program (I use Paint.net for its power and simplicity)  you record those pixel locations and then create a scale factor.  Once you have that you can make accurate (pretty good) measurements.  I have found by taking out all measurements to 2 places I can get good results.

Through time the spreadsheet has expanded to include much more.  I wanted to calculate the center of gravity so through the RC Aircraft Proving Grounds CG Calculator I found a way to do it.  I copied a lot of their work (I give them full credit) just in case the website went down and put it into the spreadsheet.  I was going to put a link here but the site seems to have an issue at the moment.  I hope it is not down permanently

I also found a moment of inertia calculator and have also incorporated it in the spreadsheet.  Information for this came from http://www.aircraftdesign.com/.  I also went to a library and checked out Dr. Raymers book.

The whole point is that my Aerodynamics calculator can be used to setup an aircraft JSBSIM FDM with good results.  I have found by tweaking an FDM after using Aeromatic to initially get things going with my calculator that aircraft fly well.  It usually requires quite a bit of work and for each aircraft the spreadsheet may need customizing, but for me I think it works well.  Here a link to the calculator https://dl.dropboxusercontent.com/u/84585372/Calculators.zip.  This is a zipped file with the calculator for 3 different aircraft so you can see how it is used for different aircraft.  Enjoy!    


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