What is it about?
A new type of pivoting-blade cycloidal propeller having the appearance of damselfly wings, which can equip aircraft with vertical take-off and landing capability was designed and tested. This propeller is emerging as an alternative solution for electrically powered Planetary Aerial Vehicles capable of operating in the rarefied atmosphere of Mars. For our prototype we did not do CFD simulations, but the experimental measurements and the filmed flight prove without any doubt the correctness of the promoted ideas. It would be interesting to find out what results are obtained by CFD simulation; in the paper are given all the constructive parameters of the propeller in order to be able to make (by those interested) CFD simulations.
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Why is it important?
In our article the theory is implemented in several experimental models. One is photographed and presented in the text of the paper, and for two of the proptotypes are attached films with their flight. The article and auxiliary materials (films, pictures) can be obtained by accessing: https://arc.aiaa.org/doi/abs/10.2514/1.J057270. All measurements / results presented in the paper are obtained on functional prototypes and not by simulation. This propeller has the appearance of damselfly wings and the advantage of low mass compared with other types developed to date. The operating mode shows similarities with the movement of these insects’ wings to generate upward vertical thrust. The theoretical analysis proves that both lift and drag contribute to the net vertical force, and the contribution of drag is at least 50%. This way of generating vectored thrust is emerging as an alternative solution to other types of propulsion in low-Reynolds-number regimes with a blade tip Mach number not greater than 0.2.
Perspectives
Drag is not always a negative factor for a flight system developed by technical means, and this is more obvious in low-Reynolds-number regimes (in the insect world or a less dense environment such as the Martian atmosphere). Until now, only in the case of study of insect flight have assumptions been made about the contribution of drag to the generation of the net vertical force required to support its own weight. Rather than looking for alternatives to increase the lift-to-drag ratio, further study should investigate the way in which drag acting on the blades can contribute to the generation of thrust in the case of flying vehicles developed for low Reynolds-number environments.
Francisc Bereczky
Echitron s.r.l.
The prototype to which we mounted and used the propeller proves that it is a completely new structure that flies (it is not a helicopter, it is not an airplane). It is a new model of "aircraft". The calculations made in the final part of the article, where a comparison is made with the performance of the Mars Helicopter (sent and recently arrived on the planet Mars), show that the propeller presented by us has at least as good performance. The propellant presented in the paper can also be used for propulsion in the aquatic and underwater environment.
Ioan Silea
Universitatea Politehnica din Timisoara
Read the Original
This page is a summary of: New Nature-Inspired Cycloidal Propeller for Low-Reynolds-Number Hovering Flight, AIAA Journal, September 2019, American Institute of Aeronautics and Astronautics (AIAA),
DOI: 10.2514/1.j057270.
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