Part 5 -- Virtual Swashplates, Longer Ranges, and Coaxial Rotors

Section 1: The Idea

Early Phases

The first time I saw the Prox Dynamics/Teledyne FLIR Black Hornet and Black Recon series UAVs, my thought instantly drifts to a scenario where it was used more than merely an eye, but can also be used as a small, swarm capable weapon system. Looking at the price however, I quickly understand why no country in this world would attempt that very scenario. The price of each unit of this "engineering masterpiece" also reminds me of how impractical it would be to have a unit slightly broken and yet the replacement bust be perfectly molded and costs more than a thousand US dollars each.

One day, I found out about the long range quadcopters that use a single 18650 Li-Ion battery which can fly up to 20 minutes on a single battery, and so I thought, "maybe if I can reduce the number of motors down to 1, I can reach roughly 80 minutes of flight time", and this is where the concepting began.

The earliest synthesized concept was not simply written into a textbook, but rather directly modelled on Fusion 360. The design itself is a combination between the 18650 quadcopter and the Black Hornet nano, with the idea of the ease of reparation in mind. The concept takes notes on the access for component replacements by placing most components on the surface of the fuselage. It also utilizes Balsa-CA composite for the whole body, making it durable while can be easily mended in case of damage. The propellers are commercial-off-the-shelf propellers and rotor blades from toy drones and toy helicopters.

Current Phase

Just when I thought my design was perfect, I stumbled upon a soviet artifact, one that would change the overall trajectory of this project. The Kamov Ka-26 is a coaxial utility helicopter that was made with an ease of maintenance and repair as one of the design philosophy. The helicopter is designed with a coaxial rotor to eliminate the torque produced by one motor while still using 100% of all power consumed as thrust, unlike conventional helicopters which uses a tail rotor which itself would consume up to 20% of the power wasted away.

This configuration will also eliminate one problem regarding the yaw of the original design, which initially was going to use a tail rotor which needs to be tuned earlier, into something that will be stable even when not yet tuned, making the concept easier to iterate. 

The two coaxial rotors are going to be interlinked with each other in order to make the virtual swashplate work. The yaw will be controlled by an aerodynamic vane instead of using differential RPM.

So far, I've only designed and compiled the components which I'm going to use to make this swashplateless coaxial helicopter. The comprehensive report will be available upon request.

Section 2: Design