Defense and Security have also deployed advanced UAVs for a wide variety of critical missions. They provide capability to fight effectively in urban areas against widely dispersed forces, while minimizing collateral damage and achieving information superiority. The UAVs have become one of the essential constituents of all militaries to perform intelligence, surveillance, and reconnaissance missions. Their roles have expanded to areas including electronic attack, suppression or destruction of enemy air defense, network node or communications relay, combat search and rescue and many others. The increasing demand and reliance on UAV in warfighting and peacekeeping operations has doubled the pace of UAV-related R&D in recent years.
The employment of UAVs by various industries and in Defense and Security missions are enabled by their propulsion system to provide them with the necessary power to propel the aircraft for forward flight or hover. Propulsion systems can advance the flight time or endurance of a UAV which is influenced by the propulsion technology used and is dependent on the aerodynamic design and amount of fuel carried. To fulfil the energy requirements of a large variety of UAVs, several variants of piston-engines and electric motors have been designed by the market players.
Propulsion is also crucial for Drone swarms. DARPA OFFensive Swarm-Enabled Tactics (OFFSET) plans drone swarms of up to 250 unmanned aircraft enter battle alongside small teams of soldiers. The agency believes these small drone armies could soon help soldiers in clear buildings in urban areas and conduct reconnaissance.
Now researchers have turned to Wireless power transfer (WPT) for Drones and Drone swarms. Wireless power transmission, wireless energy transmission (WET), or electromagnetic power transfer is the transmission of electrical energy without wires as a physical link. In a wireless power transmission system, a transmitter device, driven by electric power from a power source, generates a time-varying electromagnetic field, which transmits power across space to a receiver device, which extracts power from the field and supplies it to an electrical load. The ability to power devices remotely to eliminate the need for replaceable batteries or reliance on environmental inputs such as sunlight to provide energy offers attractive benefits.
Wireless power techniques mainly fall into two categories, near field and far-field. In near field or non-radiative techniques, power is transferred over short distances by magnetic fields using inductive coupling between coils of wire, or by electric fields using capacitive coupling between metal electrodes.
In far-field or radiative techniques, also called power beaming, power is transferred by beams of electromagnetic radiation, like microwaves or laser beams. These techniques can transport energy longer distances but must be aimed at the receiver. Proposed applications for this type are solar power satellites and wireless powered drone aircraft.
DARPA Is Exploring Ways to Wirelessly Charge Drone Swarms
A startup called Electric Sky was awarded $225,000 award from the Defense Advanced Research Projects Agency to build first Whisper Beam transmitter to provide tightly focused wireless power to drones in flight.
The first phase of the project calls for the construction and testing of a laboratory-bench demonstration system that will operate over short distances. Those experiments are expected to supply data that can be used to upgrade the system for higher power and longer range.
Electric Sky isn’t the only venture focusing on wireless power for drones. Seattle-based PowerLite Technologies, for example, is working on a laser-based system that could power unpiloted aerial vehicles as well as 5G base stations. but Electric Sky’s proprietary technology takes a different approach.
Laser and microwave beams usually start out strong, but get weaker as they move outward. In contrast, the transmission of the whisper beam starts out weak but becomes stronger near the receiver. “Whisper Beam Technology is the electromagnetic equivalent of a whispering gallery,” Millman said in a news release:, “In a whispering gallery a lone listener across the room can hear the speaker, but no one else, not even those standing directly between the speaker and the listener. The voice is too weak for them to hear. ,
Radio waves sent by Electric Sky’s transmitter self-focus on the receiver, enabling the drone to draw kilowatts of power in any kind of weather.“It’s a myth that long-distance power transmission is impossible,” Greyson said. “It just has never been economical. This new method reduces the cost of a ground transmitter and the size of a vehicle’s onboard receiver.”
Greyson said the beaming system could be used with any type of electric aircraft. “Whisper Beam technology is particularly helpful in the power-hungry phases of takeoff and climb, helping vehicle designers meet other requirements to increase range, increase flight safety, reduce peak load on the battery and reduce ground turnaround time. enables,” he said.
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