All Draw Curiosity videos are fully subtitled in English and Spanish. The blog post builds on the concepts touched upon in the video.
This is my entry for the National Academy of Engineering’s Engineering For You (E4U3) Contest – which sets the challenge of explaining a mega-engineering project in 1-2 minutes. This video was quite a monster to animate, but I’m extremely proud of the result and the fact that I went through with this! If you enjoyed my entry, please consider supporting it by giving it a ‘thumbs up’ over on YouTube.
I’m aware the video is jam-packed with information (and this is the cut-down version!) – so I thought I’d address some of the bits and pieces that I mention in the video.
Don’t super small drones already exist?
The smallest commercially available drones are approximately 4 x 4cm and 3 x 2cm. That is very small, but not as small as your average insect. House flies are approximately 0.8 – 1.2cm in length, and many other insects are microscopic, measuring 0.5 – 5mm in length! This screenshot shows my Cheerson drone to scale with a house fly and a fruit fly (assuming that each square is 1cm across).
You may have heard of the recent news release of the Robobees, which is by far the smallest flying robot created to date with a wingspan of only 30mm, crafted by researchers from Harvard University. Its main feature is its ability to perch using electrostatic forces to expend less energy in a stationary position. They are still in development and aren’t commercially available, but you can view a video of one in action here:
However, the downside is that currently they are only capable of flying tethered to their energy source, so they are neither free-flying nor completely autonomous. Their next stage of development will be to find an appropriately small battery to power it in flight.
What are microfuel cells?
This is another extremely exciting field of research. One of the reasons battery life is so short in drones is that they must expend power to carry the battery. A larger battery supplies more power, but also requires more power to be transported.
Microfuel cells use a different chemical process to generate energy and are a very promising technological field of research. They work by oxidising combustible fuel such as hydrogen, or alcohols such as methanol. In most cases, the cells aren’t really that ‘micro’, but they are capable of storing 10 times the amount of power that a standard Lithium ion battery does. The main advantage is that they employ expendable fuel, so that, as the fuel is used, the reservoir empties and thus weighs less. This means they can be recharged in seconds by replacing the fuel cartridge – as opposed to traditional rechargeable batteries which require several hours. Likewise, because low-fuel cartridges weigh less, they require less energy from the vehicle transporting it as the cartridge discharges.
The current disadvantage is they are still relatively large for a small drone. They have been successfully installed in large motor vehicles, and scaled-down versions are currently in development, with the aim of powering small electronic devices such as phones, tablets and laptops. Even smaller microfuel cells would be the ideal candidates to power micro- and nanodrones.
Is renewable energy a good source of power?
Renewable energy is an excellent back-up plan for unmanned aerial vehicles, especially those expected to make long journeys to remote locations, or to be self-sustaining in a nature reserve. By alternating perching and flying behaviour, very much like animals do, they can seek out the sun or an appropriate source of fuel, and perch to collect data in a less energy intensive fashion whilst recharging.
What is meant by energy-efficient flight mechanisms?
Animals have found ways to optimise their flight performance, either by reducing their energetic requirements or by maximising their performance in other areas such as their cruising speed or distance covered. By applying these to our unmanned aerial vehicles, we may find that we can get a more efficient use of their available power.
Whilst most UAVs have longer charging periods than flight time, animals are more efficient in their foraging and energy collection, and are more frugal in expending their available energy. This allows their flight-time to exceed the amount of time required to eat and replenish their available energy. The time estimates of ‘charge’ and ‘flight’ time displayed for insects were based on my own observations when experimenting and studying the flight of blow flies and bumblebees.
How accurate are the flight evolution dates cited at the start?
In terms of precision, obviously man-made aerial vehicles are more precise by a factor of 10,000 – but in certain areas I found it hard to define the exact milestone for men. For some, the figure that Powered Unmanned Air Vehicles have been around for ~60 years might sound quite high, and for others low.
There have been many previous attempts – the very first registered case being an attack led by the Austrians in 1849, who shuttled 5 balloons loaded with bombs over to Venice – but balloons are neither powered nor remote controlled. In 1907, Louis Breguet built the first quadcopter, and it was capable of flight at low altitude whilst tethered to the ground, but it does not really count either.
Quadcopters began to really take off in the early 1960s due to military development, and in recent years, they have also been scaled down and produced commercially. One can now purchase a drone anywhere in the range of $10 – $2000 depending on the amount of functionality required. For indoor playing I have had a lot of fun with the Cheerson CX-10 drone, so far it has proven to be incredibly sturdy and even comes with spare parts, making it a cheap investment to learn how to steer drones and whether scaling up would be of interest.
On the other end of the spectrum, you can find DJI Phantom drones which are equipped with the latest technology in terms of GPS locking, programmability, camera recording with inbuilt stabilisation and many other bells and whistles.
As a biologist and current insect flight researcher, this is precisely the topic I am most knowledgeable about. Powered flight has evolved a total of 4 times – in insects, pterosaurs, birds and bats, and all individuals in these groups are descended from a common flying ancestor in each lineage.
Insects are by far the most veteran fliers, with 430 million years of experience under their belt, and across the different orders there is a vast variety of specializations. To name a few, locusts (Orthopterans) are adapted for long distance cruising flight, capable of sustaining flight for up to 8 hours at a time; flies (Dipterans) have lost their second pair of wings which evolved into their halteres. These sensitive organs act as gyroscopes providing the fly with detailed sensory information, allowing them to be as manoeuvrable and acrobatic as all swat-evading flies are. Bumblebees (Hymenopterans) are slightly more clumsy as far as their manoeuvres go, but excel at load-carrying; and the beetles (Coleopterans), who have become the masters of wing origami, are capable of protecting their delicate wings under their carapace when not in flight.
My PhD work involves analysing slow motion videos of insects (such as those you saw in the video), so you can expect some future segments on the intricacies and beauty of insect flight!
The only group which is entirely extinct, the pterosaurs lived from 228 – 44 million years ago, but evidence from the fossil record indeed does demonstrate that they were apt fliers.
The date for the evolution of flight in birds is indeterminate, but lies in the ballpark of 150 – 100 million years ago. Recent evidence suggests it did not originate with Archaeopteryx as certain aspects of their morphology shows they were incapable of flight, and most likely they employed their wings for warmth.
Bats are the most recent fliers in the animal kingdom, evolving flight 52 million years ago.
What are the roles of First Person View (FPV) and Virtual Reality (VR) in advancing drone technology?
This was the fourth point I was going to make, before deciding that it was definitely going to overload a 2 minute video, although I alluded to it in the ‘accessible drones’ section. Now that technology is fast enough to record and stream video live from a drone to VR-goggles, it is possible to become a drone racer flying your quadcopter from a first person perspective. You can actually have a small taste of this experience by using google cardboard: insert your phone inside the box, play your favourite YouTube videos by activating the cardboard option and enjoy a cinema-like experience.
However, VR and FPV technology can be taken beyond entertainment purposes and applied to improve the quality of life of people with limited mobility by allowing them to virtually explore areas, and controlling the drone to access, carry and manipulate objects in their surroundings.
I hope you enjoyed and learned something new today! Fingers crossed for my entry to get shortlisted – if it does expect a second blogpost explaining how I made this videos as there is plenty of interesting Behind the Scenes with regards to recordings the footage and compositing the animations. Let me know what you think in the comments – do you think drones are going to change the world? If you enjoyed this blog and would like to be notified of new entries, consider signing up to the mailing list here and subscribing to the YouTube channel!