www.3ders.org

Mar 7, 2016 | By Alec

We see fantastic 3D printed quadcopters all the time, but the reality is that they use a relatively simple aviation method – at least when you have motors available. For millions of years, the animal kingdom has instead relied on wing-power – a technique that scientists have found difficult to replicate. However, as part of a study on animal flight, researchers from Tongji University in Shanghai have actually managed to 3D print a Dragonfly ornithopter, that flies by harnessing the power of flapping wings.

If you’ve ever opened a coffee table book on the history of airplanes, you’ll have seen the sometimes ludicrous flapping machines with which French, English and American inventors endangered their own lives. Jumping off church towers and so on, most of these machines never really worked. While small, often elastic-powered ornithopters (machines powered by flapping wings) were possible, transferring that power to aircraft capable of carrying humans was another matter. There’s a reason why commercial aircraft don’t feature flapping wings. However, that doesn’t mean we can’t still learn things from the animal kingdom. Over a period of millions of years of evolution, flapping wings have proved to become the most efficient and widely used technique for birds, insects and even flying fish. In contrast, humans have only been flying for a single centuries, so there’s much we can still learn.

That is why research professor Shen Hai Jun from Tongji University in Shanghai has been working on small models that mimic animal flight. The most recent result of that study is a 3D printed bionic miniature ‘Dragonfly’, which is remote controlled like a quadcopter. It has just completed a preliminary test, and showed a good flight performance, featuring upward and downward movement, hovering and even an 180 degree sharp turn. The wings are fully capable of producing lift and pull, with the electromagnetic enabling free flight. Enough to call it ‘The King of Flight’.

So how was it designed? First the research team performed an in-depth study of a dragonfly’s body structure, to get to grips with how the unusual insect actually functions. This data was subsequently taken to CAD software, where they produced simplified versions of the creature’s wings, veins, head, feet, chest and waist seconds. To this, some ornithopter features were added: fuselage, landing gear, engine mounts and other components, with the trailing of the dragonfly functioning as a rudder. Converted to an STL file, they finally 3D printed all those separate ornithoper parts.

But of course working on such a scale seriously limits your equipment options. Based on past experience, the Dragonfly was equipped with a 7mm diameter brush motor and the corresponding deceleration group as a power source, and  3.7 volt lithium batteries for energy. Infrared two-channel control was used for communication, with one channel focusing on wing beat frequency (ie: flight altitude and speed), with the other controlling direction. The Dragonfly's rudder is a homemade miniature servo with solenoid coil with a 4 mm diameter.

After assembly, a 0.1 mm polyethylene plastic film was glued to the dragonfly veins to form the wings. The completed Dragonfly weighs just 15 grams, is 16 cm in length and has a 15 cm wingspan – one of the smallest 3D printed flying machines we know of. But it’s also one of the best tested, as the Dragonfly was taken to the wind tunnel in Tongji University’s tiny airplane laboratory. The test results show that the power system can produce more than ten grams of lift and pull power, which meet the Dragonfly power requirements of flight. Incidentally, the wind tunnel used was the same as used by the Wright brothers over a century ago. Recovered by the laboratory, the lift/drag mechanical scale has since been replaced with a more precise electronic scale.

The results are certainly impressive, and this is one of the most inspiring 3D printed flying machines we’ve ever seen. Remarkably, it is actually just one of the several 3D printing projects that the professor and his team have been working on. Last year, they developed 3D printed flying fishes (based on erythema fins flying fish and white tip flying fish) that also went through a series of wind tunnel tests.

“We are the first in China and the world to directly test 3D printed miniature aircraft in wind tunnel tests. The flying fish’s lift to drag ratio can be maintained at between 5 to 6, which is the upper limit of small aircraft lift to drag ratio for inside use. This shows that the two flying fishes have excellent aerodynamic performances,” he said. The team previously also worked on 3D printed butterflies, flies, cicadas and more. “We hope that these 3D printed insects can help us reveal the mysteries of animal flight and result in more knowledge for human development,” Shen concluded.

 

 

Posted in 3D Printing Application

 

 

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K wrote at 3/12/2016 5:11:52 PM:

They just stole this design from thingiverse... http://www.thingiverse.com/thing:951687 China always does this

Flybywire wrote at 3/10/2016 9:16:40 AM:

Thinkpools dragonfly in Thingiverse doesnt fly at all. Thinkpool provided a video showing it dropping like a stone. Why that was put on Thingiverses frontpage eludes me.

Jeremy U wrote at 3/9/2016 5:27:29 AM:

This is Thinkpool from Thingiverse and I want to thank the Tongji University in Shanghai for using my design. http://www.thingiverse.com/thing:951687 I know the university is a honorable and reputable institution that would never steal a design without some sort of Attribution. Check out my other flying designs including my Dragonfly on Thingiverse. http://www.thingiverse.com/thinkpool/designs I will continue to make flying wonders, thank you.

craig billings wrote at 3/8/2016 1:27:05 PM:

It's called 'CHINA innovation' aubenc. *sarcasm*

aubenc wrote at 3/7/2016 8:00:29 PM:

There's something that sounds/looks at least "weird" in this post. Looking at the 1st pics here (2nd, 3rd and 4th)... It doesn't look like http://www.thingiverse.com/thing:951687 has something to do with any Shanghai University. Looking at it the other way around, the shanghai Univ. work looks a lot to the thingiverse thing. Now, who was the first? Has one the permission from the other to use the other one's work without any attribution? Are they part of a team, collaboration or whatever? I just don't know but, still, there's something that looks not right to me here.

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