For 300 million years dragonflies have maintained their independently controllable, four winged form – whilst other flying insects have repeatedly modified or reduced one pair of wings or mechanically coupled their fore and hind wings. Previous studies into the flight of four-winged animals have suggested that the four winged form is not as efficient as using two wings.
In order to hover a dragonfly, just like a helicopter, has to push air downwards – this is referred to as the ‘wake’ or ‘downwash’. Any air motion that isn’t downward fails to support the body and is wasteful. This study shows that dragonflies are able to use their lower wings to recover energy wasted in side to side air motion in the wake – if they flap their wings at right time.
“I’ve been repeatedly struck by how inefficient dragonflies seem to be when they fly and I wondered whether they were using any additional tricks to become more efficient,” said Jim Usherwood, Wellcome Trust funded researcher at the Royal Veterinary College and co-author on the paper. “By working with Fritz-Olaf Lehmann, who has been developing flapping robots, we were able to simulate dragonfly flight and measure the aerodynamic forces. We found that two pairs of wings can allow the dragonfly to produce higher forces, allowing acceleration and climbing, whilst the lower wings are able to reduce energy wasted if the wings flap at the right time.”
Working with robot dragonflies allowed the researchers to look at what would happen if the front and back wings flapped with different timings – which would not have been possible to simulate with real dragonflies. Whilst most of the flapping timings were less efficient than hovering with one pair of wings, the scientists discovered that there were some instances when flapping with two pairs of wings was more efficient because it required less power to lift the same weight as just one pair of wings.
Whilst this research demonstrates that two pairs of wings have some aerodynamic advantages which have been used in insects for more than 300 million years, it could also be used to aid the development of micro air vehicles based on flapping designs. Such aerodynamic mechanisms used by dragonflies could, if technically feasible, be applied to allow micro air vehicles to fly a little longer or carry a larger load.
Significantly more productivity in USP lasers
06.12.2016 | Fraunhofer-Institut für Lasertechnik ILT
Shape matters when light meets atom
05.12.2016 | Centre for Quantum Technologies at the National University of Singapore
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
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07.12.2016 | Health and Medicine
07.12.2016 | Life Sciences
07.12.2016 | Health and Medicine