Ars Technica published a story in October about a new test plane that flies without control surfaces. The trick is that by directing jets of air over the trailing edge of the wing, one can effectively fake the existence of real flaps, elevators, and ailerons. Using so-called “fluidic control” makes for less complex systems (mechanically, at least) which in turn make for lighter, more maneuverable, less costly, and longer lasting aircraft.
I don’t know if the engineers who developed this design actively pursued biomimetic design, but I think this is a great example of biomimetic design done right.
While I can’t be sure, it seems a reasonable inference that, originally, aircraft control surfaces – flaps, ailerons, elevators, and rudder – were designed to mimic a bird’s wing. (That was certainly Leonardo’s thinking.) A bird can change the shape of the airfoil it’s wings assume to change its aerodynamic characteristics and thus control its flight. Each type of control surface on a plane changes the shape of the wing to achieve a specific kind of control. That is, aircraft mimic the structure of birds.
However – and this is a problem I’ve always had with biomimetics – mimicking structure is rarely the right thing to do. Indeed, the best examples of biomimicry in design usually start with a naturally occurring structure, but then re-design it using the full power of all our knowledge and available technology. Consider velcro, which was first conceived of by George de Mestral while considering how burrs “fastened” onto his pet dog’s fur. Actual velcro is significantly different in structure from either burr or fur, but it is functionally equivalent.
What I see in this new aircraft design is an attempt to see past the structure of birds to the actual function, and then to look for alternative means to achieve those functions that poor Mother Nature lacked when she was busy evolving the flight of birds. This is what I think real biomimicry is about. I think this because Nature is very much constrained in ways that we are not. It may well be that in some cases, we cannot find a better structural solution than what Nature has evolved. However, we should never just accept Nature’s solution as the best; we should only use it as a starting point. As in the case of fluidic control, if we can lower cost and weight, and improve reliability and performance – well, then I think it would be foolish to stick with what Nature came up with.