Project Status; There are no planned updates for PROP_DESIGN. I have been working for many years, to complete the project. At this point, I have it as close to perfect as I can make it. That being said, if I discover something to improve, I will go ahead and do so.

    • 11/15/18 (Most recent update):
      • Added airfoil efficiency information to the output of PROP_DESIGN_ANALYSIS. This lets you know how well the airfoil is performing and if it is stalled or not. Moreover, it lets you know if you can use a flat plate instead of an airfoil
      • Updated many of the *.plt files so that dashed lines are shown as intended. gnuplot 5.0 changed the way dashed lines are handled
      • Updated my software recommendations. They are located at the bottom of the recommendations page
      • Other various website updates
    • 08/03/18 (Last significant update):
      • Fixed bug in PROP_DESIGN_OPT takeoff optimization. Fan efficiency wasn't being updated during the pitch optimization phase
      • Order of inputs from PROP_DESIGN_OPT to PROP_DESIGN_XYZ were not in agreement. This effectively broke XYZ for all but one blade orientation. It was only by dumb luck that XYZ even functioned at all, when using input files generated by OPT. I updated XYZ input order to agree with OPT generated files. Make sure to update your XYZ files
      • Wake properties were updated in all codes. This also includes fan efficiency. Because of this, geometry will change, for any case optimized for takeoff conditions. Therefore, I updated the computer case fan example geometry.
      • Updating the wake properties affected several examples. They have all been updated
      • Updated many of the notes files. Wake properties should be much more clearly explained
      • Updated the user manual

There is no change log. I started developing PROP_DESIGN in 2008. I tried making a change log a couple of different times. However, it quickly became so long that there didn't seem to be value in it. Who is going to read through pages and pages of cryptic change notes. The important thing is to use the current version of PROP_DESIGN.


All files I have uploaded are virus, spyware, and malware free. However, it is a good idea to scan all files you download, to ensure they haven't been tampered with.


See the support page and the about page for many applications of PROP_DESIGN. This includes; hovercraft, VTOLs, turbofans, adjustable thrust vectoring nozzles, stators, and more. Description:

Documentation Folder:

  • The PROP_DESIGN User Manual folder - Contains the PROP_DESIGN User Manual, applicable to the 64-bit Windows version of PROP_DESIGN (as the other versions of PROP_DESIGN did not exist at the time the document was written). I recommend reading the PROP_DESIGN User Manual, even if you are not going to use the 64-bit Windows version of PROP_DESIGN. This is due to the fact that all versions of PROP_DESIGN are very similar. Moreover, once you understand how the 64-bit Windows version of PROP_DESIGN works, you can easily figure out how the other versions function
  • The Reference Information folder - Contains information which, among other things, aids the understanding of the PROP_DESIGN source code, derives some important equations, and answers some common questions. It also contains several additional examples. These examples cover; counter-rotation, hovercraft, VTOLs, turbofans, and stators

Fortran Compiler Comparison Folder:

  • BENCHMARKS folder - Based on PROP_DESIGN_MAPS. The only difference is the addition of numerous *.bat files. The *.bat files are what is responsible for actually running the benchmarks

Optional Documentation Folder:

  • The Airfoil Model folder - Contains information regarding the airfoil model utilized by PROP_DESIGN
  • The Atmospheric Model folder - Contains information regarding the atmospheric model utilized by PROP_DESIGN
  • The Stall Model folder - Contains information regarding the stall model utilized by PROP_DESIGN

Optional Programs for 64-bit Windows Folder:

  • The AIRFOIL_CFD_INPUTS folder - Contains a Fortran 77 program that helps correlate airfoil wind tunnel data to CFD inputs. You input airfoil chord, Reynolds number, and Mach number. Geopotential altitude, density, speed of sound, kinematic viscosity, pressure, and temperature are output. This is useful when the chord analyzed by CFD is different than what was tested in the wind tunnel. This causes the atmospheric properties to change
  • The ATMOSPHERIC_PROPERTIES folder - Contains a Fortran 77 program that will output various atmospheric properties. It uses the same atmospheric model as PROP_DESIGN. You input geopotential altitude in units of feet. Density, speed of sound, and kinematic viscosity are output
  • The ATMOSPHERIC_PROPERTIES_ALT folder - Contains a Fortran 77 program that will output various atmospheric properties. It extends the atmospheric model used by PROP_DESIGN. You input geopotential altitude in units of feet. Density, speed of sound, kinematic viscosity, pressure, and temperature are output
  • The VELOCITY_CONVERSION folder - Contains a Fortran 77 program that will convert true airspeed to Mach number. Moreover; true airspeed (TAS) in units of mph, combined with geopotential altitude in units of feet, are used to determine aircraft velocity in units of Mach (which is an input to PROP_DESIGN)

PROP_DESIGN 64-bit Windows Folder:

  • The PROP_DESIGN folder - Contains various versions of PROP_DESIGN. Each version of PROP_DESIGN contains examples. The best way to get started with PROP_DESIGN is to review the PROP_DESIGN User Manual and run the examples. If you are interested in aircraft propeller theory, study the PROP_DESIGN source code files and reference information
  • The PROP_DESIGN_UNDOCUMENTED folder - Contains undocumented versions of PROP_DESIGN. They were created to study different aspects of PROP_DESIGN and aircraft propeller design in general. One particularly useful version, creates performance maps for constant speed propellers. Although these versions are undocumented, if you are familiar with PROP_DESIGN, you will have no trouble figuring out how to utilize them. Since I am finished developing PROP_DESIGN, I decided to share them with you, rather than just delete them

Compatibility Notes:

All versions of PROP_DESIGN have been tested on AMD and Intel x86 processors. However, they should work on any processor capable of performing 64-bit floating-point arithmetic. You would have to re-compile the source code files to experiment with other processor types.

32-bit Windows:

If you need to run PROP_DESIGN on 32-bit Windows, you will have to re-compile the Fortran 77 source code files. I recommend using the Intel Fortran compiler, in order to achieve the highest performance. If you would rather use gfortran, mingw-builds is a good option.


In November of 2012, I tested PROP_DESIGN on Linux. PROP_DESIGN works fine on Linux, as expected. For use with Linux, place the 64-bit Windows versions of PROP_DESIGN in your Documents folder. Delete all *.bat and *.exe files. You will need to install gfortran and gnuplot. Make sure the wxt terminal is the default for gnuplot. Lastly, re-compile all source code files, using gfortran.


In January of 2014, I tested PROP_DESIGN on an Android tablet using three free apps. I was able to compile and run PROP_DESIGN using the CCTools and 920 Text Editor apps. I was able to view all *.plt files using the Mobile Gnuplot Viewer (free) app. These apps require a fair amount of free storage space to install.


You may have to edit all of the *.plt files. Moreover, the paths to the *.dat files need to match the locations of the files on your particular device. This seems to be a limitation of the Mobile Gnuplot Viewer (free) app.


The Android tablet used a 32-bit ARMv7 processor. There were no issues compiling or running PROP_DESIGN. Comparing results, obtained with the 32-bit ARMv7 processor against those from a 64-bit x86 processor, showed agreement down to the last significant digit.


During Android testing, I did have one issue. CCTools froze, while installing the Fortran add-on. I rebooted the tablet and re-opened CCTools. The Fortran add-on showed as installed. However, once I went to use it, it wasn't actually installed. So I uninstalled the Fortran add-on and re-installed it. There were no issues during or after the second install.


October 2018 Update; I noticed CCTools is no longer available on Google Play. I'm not sure why that is. However, the developer's website is still offering the program. I updated the link to CCTools, so that it points to the developer's website. I haven't found any other Fortran compilers for Android. Given this, it may not be worth trying to get PROP_DESIGN running on Android. It seems to be quite a big hassle. It also needs an Android tablet, which seem to be out of favor as well. The idea was to make it easy to design a propeller for a prospective customer on the fly. So if you were in a meeting or at a trade show, you could ask the prospective customer a few questions, and generate a design right there. So it was a nice idea, but somewhat laborious to execute with the current state of things. If someone were to re-write PROP_DESIGN, specifically for tablets, it could make things a lot easier. This would include the graphics viewing aspects that gnuplot handles currently. Creating a tablet specific app would negate the need for users to compile the source code themselves. Unfortunately, coding for Android, iOS, etc... is way outside my knowledge base. So this is something someone else would have to undertake. If you do decide to do this sort of thing, please call your app something other than PROP_DESIGN. So as not to confuse your work with mine.


Another thought on this topic is, there are now Windows tablets. There wouldn't be any issue with using PROP_DESIGN on those. You wouldn't have to do anything different than the regular version of PROP_DESIGN. Unless the tablet uses a different kernel than the x86 64-bit one that the provided executable files are for. In that case, you would just re-compile the source code for your given processor. However, this is something you probably already do, to get the best performance. The included executable files simple try to function on the most types of processors. There is no way for me to optimize the executable files for every type of processor available.