BEYOND BIOLOGICALLY-INSPIRED INSECT FLIGHT

Important philosophical differences exist between “Biomimetic” air vehicle designs and “Biologically-Inspired” air vehicle designs. This paper describes these differences with application to micro air vehicle designs. The initial biological inspiration may not always be sufficient to lead to a viable and implementable design, so techniques not found in creation may need to be employed. Just as the wheel is not a biological development, but results in optimal solution to various locomotive problems, so too are there aerodynamic methods which leverage biology, but go beyond biological schemes to produce higher performance, manufacturable solutions to flight at small scales. The fundamentals of flight at these scales is discussed and an example is given of a biologically inspired system that extends the design beyond biomimicry. 1.0 BIOLOGICAL INSPIRATION Many researchers have turned to birds and insects as models in an attempt to leverage what already works at small flight scales. In most cases however, a biomimetic approach has been taken wherein an avian or insect analog is copied. Since everything in creation capable of powered flight uses flapping wings, researchers have endeavored to make flapping wing machines. Almost universally, these flapping machines restrict their motion to kinematically-correct, sym metric flapping that is often mechanically coupled, allowing only hovering or steady forward flight. [1] These designs do not replicate the mechanisms used by the insects and birds to modulate the flight envelope in speed, direction, and orientation. Study of the unsteady aerodynamics of the flapping wing at a design point is the justification for creating these mechanical testbeds, but often free flying systems are extrapolated from these experiments with little regard for the complexity of miniaturization, full control, and self-powered free flight in a machine that are manufacturable. It is therefore critically important to make a distinction between biological mimicry (biomimetics) and biological inspiration. A completely biomimetic wing flapping solution is difficult to design with current technology and may be even more difficult to implement. On the other hand, bio logical inspiration may lead to a better solution for a given design space than that afforded by the biological entity itself. Therefore biological models serve as a good starting point, but the design must not be constrained by the limitations of the model– in fact, going beyond the biological model could provide an even better solution than the original source of inspiration.