I recommend the pusher configuration, placing the propeller behind the fuselage or wing, for traditional aircraft (those that create lift using a wing). In lieu of tiltrotors, helicopters, and/or quadcopters; I recommend thrust vectoring nozzles. Thrust vectoring nozzles create lift by redirecting the flow from a ducted propeller (a.k.a. axial flow fan), they can be fixed or adjustable. To create static pressure, I recommend placing a diffuser behind a ducted propeller. The use of a ducted fan in combination with a diffuser is a replacement for an axial flow compressor. An axial flow compressor utilizes a rotor and stator to increase static pressure (the combination of a rotor and stator is called a stage). Velocity is constant through an axial flow compressor, this requires area to decrease. The diffuser creates static pressure by decreasing velocity and increasing area. The combination of a ducted fan and diffuser has many benefits over an axial flow compressor; higher thrust-to-weight ratio, higher efficiency, less cost to manufacture, cheaper to maintain. However, since axial flow compressors typically utilize multiple stages, the combination of a ducted fan and diffuser will not create as high of a pressure ratio as a typical axial flow compressor. Axial flow compressors require tight tip clearances. Ducted fans do not require tight tip clearances, regardless if they are used by themselves, with diffusers, or with thrust vectoring nozzles. Below are pictures of these configurations:


Sweeping the airfoils is recommended over sweeping the blade. You should only use sweep when the vehicle velocity is greater than Mach .5. You can not tell visually if the airfoils are swept or not. Many propeller manufacturers create the illusion of sweep by manipulating the chord distribution (one such example is scimitar blades). Many propeller manufactures also tout the virtues of sweep for low speed aircraft, don't let them fool you.


Below are pictures showing the same blade with two different sweep methods. They both perform the same aerodynamically. However, the swept blade configuration may cause structural problems. Therefore, using the swept airfoil method is always advised.


I recommend the following software for PROP_DESIGN users:

  • Force - Fortran IDE; No longer developed, but makes it very easy to view, edit, and create Fortran code. I don't install the version of GCC that it comes with, as it is out of date
  • gnuplot - Powerful open source scientific plotting software. PROP_DESIGN relies upon gnuplot for all plot visualization
  • Hanley Innovations MultiElement Airfoils - Appears to be the best airfoil analysis program available. Not only can the program calculate subsonic, transonic, and supersonic flow regimes, it can also calculate post stall behavior. Dr. Hanley has a blog post on the topic here; I haven't used the product personally, however, due to the cost. I recommend using MultiElement Airfoils to create your own airfoil and stall models. I have evaluated everything else available and nothing seems adequate. Otherwise, the best option is wind tunnel testing
  • Intel Parallel Studio XE - Best Fortran compiler available. Moreover, it creates the fastest running executable files
  • Keyshot - Rendering program; Easy to use, great results, no expensive GPU required
  • Mathcad - One of a kind general math and scientific documentation program; You can use it to solve common math problems and annotate pictures by placing formulas over them
  • Mecway - FEA program; Very affordable, easy to install, easy to use, can export the cold shape, accurate, great support from the developer. I use it for isotropic materials such as aluminum. Not sure how good it would be for composites. Can perform modal analysis with stress stiffening and spin softening
  • Rhino - NURBS surface modeller; Imports PROP_DESIGN *.XYZ files, lots of 3rd party plugins available, very popular program, utilizes it's own kernel

The following software is worth checking out as well:

  • ANSYS - The hands down leader in CAE software; I have used ANSYS Workbench since it's inception. It's strong points are contact, meshing, and ease of use. It has some frustrating things as well. I prefer Mecway when appropriate to use. ANSYS is one of the most capable CAE programs available, albeit one of the most expensive. However, the student versions of ANSYS are free. The new ANSYS Discovery Live product looks like a real game changer as well
  • mingw-builds - Windows version of GCC; Contains an open source Fortran compiler called gfortran. The executable files are not as fast as those created with Intel Fortran. However, gfortran is free. This is the version of Fortran that I compare the Intel Fortran compiler against in my Fortran Compiler Comparison
  • MoI - NURBS surface modeler; Fantastic interface, very affordable, very easy to use, the developer offers amazing support, the user community is incredible as well. It's a tough call between Rhino and MoI. I have used both but went with Rhino because it worked with PROP_DESIGN point files out of the box. MoI required a custom script that the developer provided. Also, Rhino has more functionality and a lot of optional 3rd party plugins. MoI is worth checking out however. It may be for you