This article is from
Creation 42(2):20–21, April 2020

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Flapping flight challenge



The rising domestic popularity of UAVs (Unmanned Aerial Vehicles, colloquially ‘drones’) has been made possible by the technical advances made in their performance, reliability, and affordability. The most common form is a quadcopter (four-rotor helicopter), piloted remotely by the likes of wedding photographers, video-makers, and recreational hobbyists.

However, there is room for improvement yet. Many are eagerly monitoring scientific progress towards making flapping-wing robots, inspired by winged creatures’ amazing manoeuvrability and energy efficiency. Insects, bats, and birds fly with ease through caves, car parking basements, and dense forest canopies. And flapping wings are generally more malleable and move with lower tip speeds than drone rotors do, therefore would inflict less damage in the event of a UAV making unintended contact with people or property.

Also, for most flight conditions that would be faced by smaller-scale robots, it has been found that flapping wing motion is at least twice as efficient at generating lift than rotary wing movement (as per revolving drone rotors), especially when hovering.1

For these and other reasons bio-inspired flapping-wing flight has been an intense area of biomimetics engineering interest for at least the past two decades. There have been noteworthy advances in our knowledge and understanding of aeronautics. However, practical flapping flight remains a huge challenge.

Actually, engineers face many challenges, especially in the ‘nano’ (insect-size) range.

The drone must be constructed of materials that are strong, yet lightweight, capable of matching the robustness and precision of an insect’s wing-muscle system.

There must be a lightweight power source. But to date, actuators (devices that convert energy into movement) and batteries fall way short of matching the power and energy capacity of living tissue.

And crucially, as a Nature journal writer put it, “the sensing and control algorithms that animals routinely use to maintain steady flight and to manoeuvre are mind-bogglingly complex.”2 So mind-bogglingly complex in fact that even our best supercomputers struggle to mimic these algorithms. And that’s despite the processing system of a supercomputer having many millions of components, compared to the efficiency of a typical insect brain with only a million neurons or so.

The RoboBees pictured above are still connected to a thin cable for power. A number of different RoboBees have been designed to conduct an array of movements including flying and some (pictured left) with the ability to land in water, swim and then propel themselves back out of the water. The bioinspired microrobots are being designed to operate in a variety of environments for numerous applications such as search-and- rescue and environmental studies. (Philip Robinson)

In short, existing technology currently lags far behind nature in the quest to achieve sustained, powered, flapping-wing robotic flight. A specific example of a recent research ‘breakthrough’ highlights this in ironic fashion.

“Sustained”(?) flight of the RoboBee

A team of researchers announced they have demonstrated “sustained untethered flight of an insect-sized flapping-wing microscale aerial vehicle.”

Before this, attempts to design insect-sized robots (i.e. no heavier than 0.05 g (0.0176 oz.) and maximum wingspan 5 cm (2 in.)) were constrained by having to stay tethered to an offboard power source. (Existing battery technology is too heavy for microscale aerial robots.) But these researchers ingeniously got around that problem by installing a photovoltaic array (solar panels) on their tiny four-winged robot. So long as there was artificial lighting at least three times as intense as natural sunlight this arrangement was able to provide the 110–120 milliwatts of power consumed by the device, dubbed the RoboBee X-Wing. The researchers said their system thus “matches the thrust efficiency of similarly sized insects such as bees.” Their boldest claim, however, was: “This insect-scale aerial vehicle is the lightest thus far to achieve sustained untethered flight (as opposed to impulsive jumping or liftoff).”3

A reviewer in Nature, while giving due credit for the significant breakthrough aspects of this work, warned that some might quibble with the claim that RoboBee’s flight was “sustained”. That’s because “the robot flies for just under a second before veering off out of view, presumably heading for a crash landing.”2

So, there’s a fair way to go yet! And there’s another, fundamental ‘worldview’ problem underlying the flapping flight challenge. Much of the research effort is framed in an evolutionary context. E.g., evolutionists hope that “biologists can use flapping-wing robots to address fundamental questions about the evolution of flight and the mechanical basis of natural selection.”2 But can ‘evolution’, portrayed as a simple step-by-step process over millions of years, really account for the origins of flapping flight? Or even just the “mind-bogglingly complex” algorithms that flying creatures “routinely” use to maintain steady flight, and to manoeuvre?2 IT experts would readily admit that a partially-complete algorithm is of not much use to anyone. Why then should anyone believe that natural selection would have favoured any incomplete flight algorithm, every step of the way?

Surely anyone, layperson or expert, encountering a RoboBee or other aerial vehicle would see the inherent design features as being purposeful and deliberate, and therefore conclude that it must have been designed. And that whoever was responsible for designing it must have had at least a modicum of intelligence. So if ‘intelligent designer’ is a logical conclusion from viewing the attempted robotic mimics of bees, birds, and bats, how much more so for the living originals—especially since the copies mostly still fall way short in so many ways? Thus the positing of an intelligent designer of life is eminently reasonable, and rational.

The Bible tells us who that Intelligent Designer is—in wisdom He made all creatures, great or small, the earth is full of them (Psalm 104:24). So, not to ‘evolution’ but instead to God be the glory, great things He has done.

Posted on homepage: 22 March 2021

References and notes

  1. Zheng, L., Hedrick, T., and Mittal, R., A comparative study of the hovering efficiency of flapping and revolving wings, Bioinspir. Biomim. 8:036001. Return to text.
  2. Breuer, K., Flight of the Robobee, Nature 570(7762):448–449, 26 Jun 2019. Return to text.
  3. Jafferis, N. and 3 others, Untethered flight of an insect-sized flapping-wing microscale aerial vehicle, Nature 570(7762):491–495, 2019. Return to text.

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