Silent Drones Idea Stream 2021. Drones are now an increasingly important part of our lives. Some professions use drones every day. For example, if you look at the lives of US soldiers, they will often use small drones called RQ-11 Ravens to provide last-minute reconnaissance, surveillance, and intelligence that’s critical to saving the lives of soldiers. Now aside from military applications, drones have many other applications. And it’s estimated that overall, drones are about a 40 billion dollar a year market. Applications include, as well as in defense, emergency services, agriculture, construction, and oil and gas. Now if we think about the future, going beyond what drones are used for today and beyond the entertainment uses of drones, there’s also the potential for package delivery. This example here is in Scotland,

where drones have been used to deliver COVID-19 test kits. But a bigger market, in the long run, would be package delivery, for example, what Amazon is doing with Amazon Prime Air, where you could potentially get packages delivered to your home in minutes rather than days. Now that has been forecast to be a 50 billion dollar a year market, so potentially a huge opportunity for drones and their application. Now what many of these different applications have in common, both existing applications like intelligence, surveillance, and reconnaissance, and future applications like package delivery, are that their ability to be effective is constrained by noise. And that noise comes from the propellers. So propeller noise is a key constraint on the growth of drones in these applications. What we are proposing to address this is to develop a silent propulsion system. In other words, a propulsion system for drones that has no moving parts. The physical principle that this operates on is called electro-aerodynamic propulsion. This works by charging a wire to a very high voltage, such that the air around it gets ionized, meaning electrons are stripped off, leaving positively charged ions. These ions are accelerated electrostatically towards a negatively charged airflow shape. Those ions collide with neutral air molecules, transferring momentum to them and creating an ionic wind. This is the mechanism of creating propulsion with no moving parts like propeller blades. Over the last ten years at MIT, we’ve advanced the basic understanding of that, and then developed a flying prototype airplane which first flew in 2018. The airplane prototype is shown here. It’s about five meters in wingspan, flew for about 10 seconds, although it had an endurance of 90 seconds, and was the first flight of an airplane with no moving parts. If we zoom in under the wings, you can see how the propulsive force is generated. That’s by an array of wires that generate the ions, and then an array of air force that will neutralize those ions, with a wind being generated under the wing. Now let me show you a video comparing the first flight of this airplane to a flight of the Raven. This will give you a sense of how quiet ion propulsion is compared to conventional propulsion as it’s used in the Raven drone. [flight with no propeller noise] [loud drone sound] [flight with no propeller noise] [loud drone sound] [flight with no propeller noise] What this demonstrates is that you can hear conventional propulsion from many, many tens of meters away, whereas, within a few meters, ion propulsion is completely silent. That clearly has value in the

application, such as intelligence, surveillance, and reconnaissance, where you wouldn’t want to reveal your position, and is useful in cases like package delivery, where silent package delivery is much more likely to be accepted, and also in other areas like traffic monitoring or air pollution monitoring where you don’t want to create noise pollution. Now we’ve developed that version 2 aircraft which flew for 10 seconds but had a 90-second endurance. We’re now working on version 3 which has significantly advanced the technology over version 2 in 2018, such that now we can target endurances of up to 30 minutes carrying a small payload. Now that’s not quite competitive yet with the RQ-11 Raven, but we think that’s getting to the point where with a successful demonstration here, we will be at the edge of commercializing the technology and producing a small-scale drone. So our overall trajectory is, over the last ten years we’ve developed and published the fundamental science. Now we’re advancing to the point of a demonstrator with an outdoor flight of some tens of minutes, and we see that as the critical staging point to then starting a company that will aim to produce intelligence, surveillance and reconnaissance targeted drones, as well as drones that can apply to other applications such as environmental monitoring. If we look beyond the next few years though, we see that such drones could potentially be useful in the 50 billion dollars a year market which is package delivery.