After conducting an eight year study of the winged seed, or ‘samara’, the Bennett Botanical Propeller Company completed its first prototype having discovered the samara from the maple tree, which holds the levelest flight path during autorotation, actually held potential for an aircraft propeller design. The webbed veins provide much of the aerodynamic function in addition to the overall structural support of the blade. We learned that replicating them caused such a change in thrust, it compromised the integrity of the blade so they had to be reduced in size and number.
The initial design approach was to reverse the physics; take a winged seed (samara) from the maple tree, turn it over, add another blade on the other side, provide energy to the hub (seed), spin it in the opposite direction and voila, you get thrust. When put to the test, you do get thrust, and a lot of it!
After much planning, and hundreds of tests which were non-paradigm, truly ‘outside the box’, finally, a working innovation that actually improves the efficiency of an aircraft propeller was developed.
Since those first exciting trials, continuous testing has culminated in a successful, marketable design, the UTARA (Universal Thrust Autorotation Augmenter), and now it’s available for certain aircraft.