The Future of Electric Propulsion in UAVs

Uncrewed aerial vehicles (UAVs) (also referred to as Unmanned) are becoming increasingly popular every year and, consequently, so too is the demand for electric propulsion systems. Manufacturers and developers need reliable components to give their units proper locomotion and aerial mobility. 

Furthermore, electric motors are now essential in the industry. Drones with conventional engines are either too expensive, heavy, or both, making battery-powered devices the norm., especially in the micro, small and medium-sized segments. Even where combustion engines are required, hybrid options are contributing to the ubiquity of electric power.

Recently, though, electric propulsion systems have undergone further changes. Manufacturers are creating evermore advanced systems that offer even greater efficiency, performance, and sustainability, enabling more practical UAV applications. These include precision agriculture, infrastructure inspection, search and rescue operations and environmental monitoring, to name just a few..

How Electric Motor Propulsion Of UAVs Evolved

Many commentators believe electric motors are essentially a coiled copper wire that creates rotational motion when current passes through it. And, of course, this is true: that’s precisely how systems work. 

However, the improvements in electric motor propulsion over the years have been palpable. Designs aren’t static but continually evolving to reflect new knowledge and practice. 

For example, early electric motors had low power output because of the brushed design where carbon brushes made electrical contact with the rotating communicator, allowing current to flow through the windings. 

By contrast, most modern applications use brushless electric motors with electronic signals to control magnetic field polarity. These eliminate the need for physical brushes to communicate current, leading to longer-lasting units. 

Demand for electric motors has also grown significantly over recent years because applications for lightweight powertrains are exploding. Previously, you had interest from model railway developers and school electronics departments. However, defense, logistics, surveillance, and commercial service industries all want these motors now. 

Key Advances In UAV Electric Propulsion Systems

So what advances are happening right now, and why should they excite us?

Higher Power-To-Weight Ratios

One leading development is ever-improving power-to-weight ratios. Electric motors are becoming more capable and easier to lift off the ground. 

For example, the Sparrow Series APM30 Kv300 brushless motor, available at ePropelled, can produce over 380W of output but only weighs 125g, roughly the same as a large bag of Doritos. 

Furthermore, it’s small, measuring just 41.8mm in diameter while producing a thrust of 2.2 kg due to its high-performance materials. 

The essential components and design are similar to previous iterations – such as the magnets, windings, and bearings – but the unit is made to a higher quality. As such, it lasts longer, making it more suitable for industrial applications. 

Better Cooling And Thermal Management

Electric motors are also benefiting from superior cooling and thermal management. Manufacturers are implementing advanced materials with proven track records in these applications. 

For example, the Sparrow Series APM80 Kv230 brushless motor has permanent magnets and bearings for a longer life. This robust construction allows it to work for extended periods in harsh environments, maintaining long-term performance. 

These changes are emerging faster than many industry commentators thought they would. Electric propulsion systems are becoming hotbeds for material science advances and experimentation. 

Optimized Efficiency

Manufacturers are tackling efficiency issues on electric motors, too. Engineers are rethinking designs from first principles, asking whether fundamental changes could yield better units. 

One approach has been to improve magnetic pole configuration. Manufacturers are exploring ways to increase pole count (to reduce clogging) and use Halbach arrays, which enhance the adjacent magnetic field on one side while canceling the other. 

Optimizing stator slot-pole ratio is part of this process. Engineers believe improving these arrangements can boost efficiency by slashing torque ripple. 

Finally, dynamic balancing is playing a role in efficiency optimization. These systems allow drones to maintain thrust even when changing direction without significant energy loss. 

Superior Battery Management

UAV electric propulsion systems are also witnessing advancing battery management. Engineers are exploring application-specific methods to boost efficiency while reducing heat waste. 

Higher energy density batteries (like lithium-sulfur and solid state) are being explored. These can theoretically exceed the energy density of conventional lithium-ion, opening up new levels of efficiency. 

However, the motor itself is also undergoing upgrades. For example, many now have smart battery management systems that optimize power distribution across the windings. 

Some also have adaptive power allocation systems, allowing real-time changes in energy reaching the motor based on flight dynamics. Companies are exploring intelligent systems to reduce power usage when it isn’t necessary mid-way through flights. 

Regenerative descent is also being tested. These systems allow electric propulsion motors to charge their batteries as the UAV or drone loses altitude. 

Enhanced Durability

Finally, we’re seeing engineers developing electric propulsion systems and prioritizing improved durability. New materials and concepts are making it onto the market, allowing UAVs to withstand harsh conditions. 

For example, Sparrow’s motors come with Ingress Protection (IP)-rated motors that resist dust, water, and other intrusions, allowing units to last longer. Even harsh weather and dusty conditions doesn’t affect operation. 

Benefits Of Modern UAV Electric Propulsion Systems

The benefits of using modern UAV electric propulsion systems are extensive. These units are vastly more powerful and capable than their counterparts just a few years ago. Here are three of the key benefits:  

Longer flight times. Lighter engines mean that UAVs can stay in the air longer. These longer operational durations open up new opportunities for UAV operators. They mean UAVs can spend more time inspecting and observing, and less time recharging. 

• Noise reduction. Today’s advanced brushless units are quiet, allowing most battery energy to go to useful work (i.e. keeping the craft in the air). 

• Cost-efficiency. Running an efficient electric motor, like the ones from Sparrow, makes flying drones cheaper long-term. They simply don’t require as much charging. 

Additionally, and an increasing requirement in a spectrum of commercial sectors, new electric motors offer a lower carbon footprint. 

The Future Of UAV Electric Propulsion Systems

The future of UAV electric propulsion looks to be even more exciting. While current developments are impressive, they pale in comparison to what might be coming down the pike.

Advanced Battery Technologies

Advanced battery technology is one exciting research area. Getting these right could lead to tremendous improvements in flight times. 

Solid-state batteries are perhaps the most promising right now. These are lighter and safer than conventional li-ion and able to operate at higher temperatures. 

Lithium-sulfur (Li-S) is even more promising. These batteries have five times the energy density of lithium-ion, which would revolutionize UAV endurance. Sulfur is abundant in the Earth’s crust, making it the ideal material if researchers can perfect the technology. 

Hydrogen fuel cells are a possibility, offering longer flight times compared to batteries (keeping UAVs in the air for hours), not minutes. However, they may add to system weight, reducing their utility and practicality. 

Axial Flux Motors

Another area of research is axial flux motors. These are high-efficiency and power-dense, offering lots of torque in a compact design. 

The goal of these motors is to free up space on UAVs to carry more payload. The less room motors take up, the more there is for operations. 

Carbon Nanotube Windings

The industry could also witness the development of carbon nanotube windings in the future. These are made by wrapping graphene sheets into tubes at the molecular level, allowing for superior design. 

Carbon nanotube windings are exciting because they are lighter and more conductive than conventional copper. Consequently, they may offer a better power-to-weight ratio than existing systems while making use of a cheap and abundant material (carbon). Adding these to electric motors could improve their magnetic fields further, letting them operate at a lower power consumption. 

Superconducting Motors

Superconducting motors are another possibility. These would use special materials and magnets to reduce friction further and boost efficiency. 

Physicists have known about superconducting for a long time, but achieving it at room temperature was challenging. However, special materials could convert almost 100% of the incoming electrical energy into mechanical force, reducing unnecessary battery strain if scientists can discover them and produce them at scale. 

AI-Controlled Systems

AI-controlled motor systems are also a possibility. These would presumably build on existing adaptive power management chips, adding an extra layer of machine learning to the mix. This increased intelligence would likely lead to better overall power management decisions that benefit the unit and owner alike. 

Wireless Energy Transfer

Lastly, it may be possible to use microwave or laser-based charging methods mid-flight to power UAVs. These systems could keep drones in the air for longer, allowing them to carry out critical work before returning to base. 

This continuous operation without landing is helpful for surveillance applications in the military. Wireless energy transfer would allow more time for operatives to conduct their work. 

Surveillance could also happen continuously without landing, reducing the requirement for complex UAV rotation. Each unit would have its “range,” where it could monitor the situation and report back to base. Research is underway in this area, but further safety research is also necessary.

Ultimately, the future of electric propulsion is exciting and ePropelled will be at the forefront. Our systems provide durable, lightweight designs to keep craft in the air for longer and our commitment to innovation ensures we future proof technologies in the dynamic and important drone industry.