Thank you to all the visitors. You have made all the work on this hobby/project of mine so worthwhile. When I started this project I was so surprised to see all the interest from all over the world. I always feel like I'm the only person that loves propellers so much. But you have proven me wrong. There are lots of people all over the world that love propellers too. Below are the stats as of 08/05/18. They are very typical of the project from it's inception. Although, not shown in this visitor map, people from Alaska and Japan also visit the site from time to time.


I love that PROP_DESIGN can not only be used to design the most efficient propellers, and find out details of existing designs, but it can be used to show that everyone has common interests. In a time where everyone is so divided, PROP_DESIGN helps show we all have some things in common. I also hope by giving so much freely, it will encourage others to do the same. Everyone should try to make the world a better place and hopefully PROP_DESIGN is doing that in a small way.

Old Domains:

PROP_DESIGN was previously available at:


I closed those websites a long time ago. If any of them are live again, know that I had nothing to do with it. The only place I am currently hosting PROP_DESIGN is at:

The Software and Website:

I had many reasons for creating PROP_DESIGN and releasing it as open source, public domain, software. I began studying aircraft propellers, while attending college, in the early 1990's. I found it difficult, and time consuming, to obtain information on the subject. I also found that many papers did not include source code. With the advent of the internet, several aircraft propeller design programs became available. However, these were based on old methods and had many limitations that I was unwilling to accept. The main one being the inability to design swept propellers. I had been planning on combining the work of Adkins and Liebeck with that of McCormick, to allow for swept propeller design, until I found a code called PROPSY. I re-coded PROPSY from the author's Master's thesis. Over time, I found numerous and substantial errors with PROPSY. PROP_DESIGN fixes these errors and adds many new features. Releasing PROP_DESIGN as open source, public domain software, was my attempt at giving everyone easy access to the best aircraft propeller design information available.


Recently, I have seen someone claim they developed PROP_DESIGN. While they may have worked on their own version of PROP_DESIGN, no one has developed PROP_DESIGN but myself. I have not worked with anyone on it, nor would I. This was a labor of love and it's very disappointing to see someone claim they developed it (regardless of what they may have meant). Everything on this website, including the downloads, was developed all by myself. I'm more than happy for anyone to use, and develop PROP_DESIGN, for whatever purpose they like. But I don't like anyone claiming they developed PROP_DESIGN. When you develop your own version of PROP_DESIGN, that should be made clear. Perhaps by a different name for your software. This would be similar to how I reference PROPSY (which PROP_DESIGN stems from).

Anthony Falzone, the developer of PROP_DESIGN:

I am a U.S. citizen. I earned a BSME degree, due to my childhood interest in hovercars. I worked in the aerospace industry over twelve years, prior to retiring in 2008. I worked for the following aerospace companies:

  • Hamilton Standard (Now UTC Aerospace Systems)
  • Pratt & Whitney (Division of UTC)
  • McCauley Propeller Systems (Division of Textron)
  • Atlantic Inertial Systems (Now UTC Aerospace Systems)

I contributed to the success of many notable products, some of which include the:

  • Xian MA60 regional airliners
  • General Atomics Predator B (aka Altair and MQ-9 Reaper) UAVs
  • Raytheon AMRAAM air-to-air missiles
  • Boeing Minuteman III ICBMs

I also contributed to the success of some notable services:

  • First stage turbine blade testing and analysis
  • Transonic compressor rotor (known as an  IBR or Blisk) R&D for the AFRL CARL
  • ICBM inertial sensor R&D

My involvement with these products and services included:

  • Assisting with the FAA vibration certification of the Xian MA60 composite aircraft propeller installation
  • Performing tests and running analytical models, to determine the root cause of first stage turbine blade cracking
  • Designing the three blade, solid aluminum, constant speed, aircraft propeller for the General Atomics Predator B UAV
  • Using FEA to show there was a discrepancy in the hot and cold shape models of a transonic compressor rotor being studied and tested by the AFRL CARL
  • Performing a mathematical analysis which prevented the recall of hundreds of AMRAAM air-to-air missiles, by showing a manufacturing deviation actually improved performance
  • Using FEA, testing, and mathematical analysis to determine the root cause of a complex thermally induced vibration excitation issue with inertial sensors used on Boeing Minuteman III ICBMs
  • Leading a team and performing analyses wrt ICBM inertial sensor R&D

The most rewarding project was designing the aircraft propeller for the General Atomics Predator B UAV, due to the impact that the aircraft has had on humanity.


I created all of the concepts presented below. You are free to use them for whatever you want. They were first added to the website in the 2015-2016 time frame, unless noted otherwise. They were created using PROP_DESIGN, Rhino, and Keyshot.

Adjustable Thrust Vectoring Nozzles:

Using adjustable thrust vectoring nozzles has many benefits compared to tiltrotors, helicopters, and/or quadcopters:

  • Higher efficiency
  • Longer Range
  • Higher Payload Capacity
  • Lower Noise
  • Increased Safety
  • Higher Cruise Speeds

Below is an animation of an adjustable thrust vectoring nozzle of my own design. Four struts were used for added structural stability and strength. The struts were made using the NACA 65A009 airfoil. The struts should be placed ahead of the propeller (CFD and/or testing can be used to find the ideal distance). The ducting does not contribute to the propeller's performance. In this case, the ducting only acts to guide the air into the adjustable thrust vectoring nozzles. No static pressure is developed. Thus, tight tip clearances are not needed. The blades have the same chord as the struts. The blades use the same airfoil as the struts. The engine can be an electric motor, piston, or turboprop.

Below is a low speed surveillance drone concept. The adjustable thrust vectoring nozzles are the same ones shown above. Moreover, the yellow nozzles rotate 360 degrees. The white pods, that support the adjustable thrust vectoring nozzles, would also store batteries and/or fuel and act as the landing gear. Cameras are located in the black sphere.

Below is a high speed drone concept. It would cruise at and altitude of 32,000 ft and a speed of Mach .7. It can takeoff and land vertically. It can also hover in place. The adjustable thrust vectoring nozzles are the same as those featured previously. However, the inboard nozzles have their rotation limited to 180 degrees. Using adjustable thrust vectoring nozzles negates the need for thrust reversers. The blades, struts, and wings use the NACA 65A009 airfoil.

Below is another type of adjustable thrust vectoring nozzle concept I came up with. This concept was first added to the website in September of 2017. It has the same benefits as the previous concept, however, it can be used in more ways and offers additional benefits. The previous concept creates a lot of drag. This concept can be used inside the aircraft, so no additional drag is created. The concept is also shown inside a flying wing. The ducted fan can be used in forward, reverse, up, and down. As configured in the flying wing concept, four ducted fans can be used for all flight controls. There are no flaps or anything on the wings. Pitch, roll, yaw, thrust, and reverse are all achieved using four ducted fans with adjustable thrust vectoring nozzles. The dimensions shown are in meters. It was scaled to be similar to the 747-8. However, you could make this concept to any scale or application desired. From drones, to transports, surveillance, fighter/bombers an so on.


Some details of the flying wing concept; NACA 65A009 airfoils used throughout, created in Rhino, rendered in KeyShot. This concept should easily be able to cruise at Mach .7 and 32,000 feet. Whereas, the previous concept would most likely have substantial drag issues. The flying wing can lift off and land vertically, if desired. It can also hover in place. It would be much more maneuverable than a traditional aircraft, easily being able to do amazing acrobatic maneuvers. Anything could be used to power the ducted fans; electric motors, piston engines, turbines, etc... Tip clearances in the ducts is a non-issue, as no back pressure is developed. The flying wing is not new. The first one I know of is the Ho-229. Created during WWII by the Horten brothers in Germany. Later on, Jack Northrop created numerous flying wings in the United States. There are other flying wings as well. This would be the first with this type of propulsion and control system that I am aware of.

Propeller with Stator Concept and Example:

The modern turbofan example led me to further consider combining traditional aircraft propellers with stators. This concept was first added to the website in July of 2018. Since I also provide performance information, this concept doubles as an example. More details can be found in the PROP_DESIGN download.


To get a firm grasp on the affect of stators, I compared to the existing A400M example. Even when cruising at Mach .7, ducting and sweep are not needed to achieve excellent performance. At the design point, thrust and efficiency are about the same as the A400M example. However, using stators reduces fuel consumption by more than half. If electric propulsion is used, stators would allow for over twice the range. The downside is manufacturing costs are higher and thrust-to-weight ratio is lower. Even with those drawbacks, it seems stators could be an excellent addition to traditional aircraft propellers.


Below are renderings of the propulsion systems being compared. The airframe shown in all of the pictures is a modified version of the Mach .7 drone concept. The airframe was rescaled in various ways to agree better with the size of the propulsion systems under consideration. The pictures are from the same perspective and zoom. The only difference is the propulsion system, so you can get a sense of the size differences.


Notice the blades are shorter when stators are used. In order to reduce noise and vibration issues, the rotor and stator typically have a different number of blades. Since the radius and hub end points are the same, this means the stator will have a higher r/c value (to make the blades skinnier). Also, since you are trying to remove the swirl from the wake, it makes sense to use as many blades as possible for the stator. Thus, the stator blades will be even skinnier than the rotor blades.


Also, notice the hub and support shaft are much bigger when stators are used. You can really see the affect of having to use a hep=6 for designs utilizing stators. The spinner shown in the pictures is exactly the same for both designs, only scaled up to fit the wider hub. As you can see, the same spinner looks absolutely huge, with a hep=6. Having to use a larger spinner creates additional drag.

Lastly, here is a close up animation of the propeller with stator concept and example. Pusher or tractor configurations can be used. The tractor configuration is shown. This would make it much easier to access the rotating blades. With proper design, you could change any given blade without having to disassemble the entire motor. Tractor designs also increase the velocity of the air over the wing, at low speeds. This helps with climb performance.



This is a hovercar concept I have drawn by hand since I was in middle school. I modeled the concept in clay, when I was a child, to verify the perspective views. I finally got a chance to model it in CAD.


Wanting to understand how to create hovercars is what led me to getting a degree in Mechanical Engineering. I did learn how to create hovercars. Unfortunately, they are not practical for a number of reasons. They do look cool, however, as evidenced by the photos below.


The concept shown uses six electric ducted fans. Four of the EDFs feed four plenum chambers. Two EDFs and rudders provide thrust, steering, and braking. Braking is achieved similarly to how jet engines brake. Moreover, when the rudders close, air is directed forward through vents in the wing pylons. Brake force is then equal to what the thrust force was. The rudders and vents are not shown. The occupants face each other, one seat faces forward and one faces backward (the interior wasn't modeled). There is no trunk or engine compartment. Storage bins are located behind the seats, accessible from the interior. The wheel wells act as plenum chambers. Clear glass encloses the wheel wells, in the renderings. I envisioned these as programmable screens. Whereby you could show different colors, graphics, or animations on them. For instance, you could provide the illusion of having tires and wheels that spun as you moved. Yielding a more traditional vehicle. Or you could display fun and unique graphics that highlighted your personality or mood.


The car drives itself. In the 80s, when I first started creating this concept, self driving cars were not possible. It's nice to see that they are starting to become a reality. Another feature I envisioned was a solar powered canopy that would allow the HVAC system to keep the cabin at a comfortable temperature year round, The feature would work 24/7, regardless if the car was on or anyone was in it. Nowadays, with so many children dying in hot cars, this would be a very useful feature to have. That issue wasn't around in the 80s. It was born out of having to get into crazy hot cars in South Florida. Of course, many years later, I discovered getting into crazy cold cars was no joy either. But it would also be nice to be able to leave your groceries in the car, so you didn't have to go right home. There could be a refrigerated section and a freezer section. So you could go shopping, do other things, and get home whenever you get home. Self driving cars and solar powered 24/7 automatic HVAC would make road trips a lot more interesting too.


The inspiration for the shape of my hovercar concept were the following vehicles:

  • Buick Wildcat - 1985 Concept Car
  • Oldsmobile Aerotech - 1987 Concept Car
  • Lamborghini Countach 25th Anniversary Edition - 1988-1990 Production Car

If you view images of those vehicles, you can see the resemblance. I envisioned a car that was there but wasn't there. Where air moved through it more than anything else. Nowadays, there are many vehicles that have that philosophy. Their shapes are much more aerodynamic and CFD driven than my concept. But you have to remember, I originally drew this in the 80s.

Below are renderings of the fans used in my hovercar concept. Four struts were used for added structural stability and strength. The struts were made using the NACA 65A009 airfoil. The struts should be placed ahead of the propeller (CFD and/or testing can be used to find the ideal distance). The ducting does not contribute to the propeller's performance. In this case, the ducting is only needed to guide the air into the diffusers. Because static pressure is built up in the diffusers, tight tip clearances are not needed. The blades have the same chord as the struts. The blades use the same airfoil as the struts.

Finally, here are some renderings of three different versions of my hovercar concept. These images were made specifically for use as desktop wallpaper. I currently have three different wings and two different noses modeled in Rhino. It would be overkill to post all of the available combinations. There are endless numbers of color combinations you could use as well. Besides black and white, one popular combination is grey and orange. Another popular combination is white and blue. You could let customers choose the wing, nose, and color combinations they want. Rather than have the manufacturer change them each model year as is currently done. The white and blue version is very close to what I was drawing in the 80s. The grooves in the top surface run the length of the car. Which is a bit different than how it works out in the other versions shown. Also, the shape of the wing inlets is more complex.