Tiny, high-end military drones are catching up with one of nature’s great engineering masterpieces.
A side-by-side comparison has found a “remarkably similar” aerodynamic performance between hummingbirds and the Black Hornet, the most sophisticated nano spycam yet.
“(The) Average Joe hummingbird” is about on par with the tiny helicopter that is so small it can fit in a pocket, says engineering professor David Lentink, at Stanford University. He led a team from Canada, the U.S. and the Netherlands that compared the birds and the machine for a study released Tuesday.
Birds are still far superior at flying around forests – and through cities – but Lentink predicts it is just a matter of time before machines master that as well.
“There is still a ton we can learn from nature,” Lentink said in an interview from California where robotic insects have taken flight in his lab.
For Tuesday’s study, he and his colleagues put 12 hummingbird species to the test against the Norwegian-designed Black Hornet.
Undated image released by the British Army Monday Feb 4 2013 of Sergeant Scott Weaver, of The Queens Royal Lancers launching a newly issued Black Hornet miniature surveillance helicopter during an operation in Afghanistan. (AP Photo/ Sgt Ruper Frere)
The tiny helicopters have GPS and cameras that relay video and still images to a handheld control unit. They have been described as a “lifesaver” by British troops who used them in Afghanistan to peak around corners and over obstacles looking for hazards. The Hornets are silent, sell for about $65,000 and weigh 16 grams – about four times the weight of the average hummingbird.
Hummingbirds are the only birds that hover, a feat they evolved and perfected millions of years ago as they competed for nectar from flowers.
While they have long inspired artists, poets and helicopter designers, the new study is the most detailed look yet at hummingbirds’ aerodynamic efficiency.
The scientists measured the lift, drag and power generated by wings from 12 hummingbird species. The wings were already in museum collections, so Lentink says they didn’t have to kill any birds.
The wings were put on a “wing spinner” that measured the torque required to move them. “The torque is tiny, so we did have to have very special, carefully calibrated force sensors,” says Lentink. Researchers have yet to come up with a way to replicate hummingbirds’ rapidly flapping wings so they use the spinner instead: “It creates a motion that is quite comparable except at the beginning and the end of the stroke,” says Lentink.
The Scandinavian-designed Black Hornet Nano weighs as little as 16 grams (0.56 ounces) — the same as a finch. The four-inch-long (10-centimeter-long) helicopter is fitted with a tiny camera which relays still images and video to a remote terminal. Troops used the drone to look for insurgent firing points and check out exposed areas of the ground before crossing. (AP Photo/ Sgt Ruper Frere)
Turns out hovering hummingbirds burn more energy than expected.
“Hummingbirds generate 40 per cent more power with their muscles than we thought before just to stay aloft,” says Lentink. “It’s remarkable. They’re small high-energy-density machines.”
The researchers then compared the wings to the rotor of the Black Hornet. He says the Norwegian firm, Prox Dynamics AS, provided the rotor but had no other input into the study.
They found the Hornet’s rotor to be about as aerodynamically efficient as hummingbird wings – though one species, Anna’s hummingbird, was 27 per cent better.
“It is really difficult to replicate the performance of natural flyers,” says Lentink. “The fact that we are now coming close really tells you engineering is catching up.”
Undated image released by the British Army Monday Feb 4 2013 of Sergeant Scott Weaver, of The Queens Royal Lancers launching a newly issued Black Hornet miniature surveillance helicopter during an operation in Afghanistan. (AP Photo/ Sgt Ruper Frere)
But he says flying robots and drones are still no match for the way birds manoeuvre though forests and “city canyons.”
Wind gusts and “complex environments” are still big problems. “We have to work on making these things safer so it doesn’t rain drones,” says Lentink, noting that hobbyists’ drones often crash.
Fuel systems are another challenge. The Black Hornet can fly about 25 minutes before its batteries need a recharge.
“If we could have robots that could drink nectar it would be fantastic,” quips Lentink, whose engineering team looks to nature for inspiration.
Study co-author Doug Altshuler at the University of B.C., who studies hummingbirds, could not be reach for comment.
Cool – and not so cool – uses for drones
The Norwegian firm Prox Dynamics AS will not comment on whether it has sold any of its Black Hornets in Canada, but there are lots of potential uses in the country for fast-evolving drones, or unmanned aerial vehicles (UAVs).
- The Aeryon Scout four-rotor quadcopter, produced by a Waterloo, Ont., company, has been taking images of B.C. forests, monitoring salmon populations and assessing train derailments.
- Agriculture and Agri-Food Canada has been experimenting in Quebec with a metre-long quadcopter to keep an eye on crops by taking high-resolution images that can reveal plant health.
- Police are increasingly testing and using unmanned aerial vehicles to get a bird’s-eye view of accidents.
- The federal privacy commissioner issued a report last year that warned UAVs will be a “game-changer” as the technology proliferates.
- UAVs and facial recognition technology may make it possible to identify individuals at political protests. UAVs might also be used to track where people drive their vehicles.
- Long-range military UAVs can now track moving objects from kilometres away by day or night and may soon also be capable of tracking through walls.
SOURCE: SMCC/Science Pages
