Aerodynamics and energy management of aerial drones
Optimizing the energy autonomy of the drones is a crucial issue for both civilian missions and military operations. The ability of a drone to travel long distances without recharging or refueling can determine whether a mission is successful or not.
However, improving the energy consumption of drones and securing their operations while multiplying the missions remains a major challenge. What are the solutions to increase the distance travelled? What are the advantages of swarm missions, aerodynamic optimization principles, and technological innovations that could revolutionize this field? Fine understanding of the phenomena combined with innovative designs make possible more efficient and sober designs, able to meet the increasing demands of users.
Control the energy management of aerial drones to optimize their autonomy
Modern drones, whether used for civilian or military missions, face significant operational constraints in variable and complex environments. The limitation of energy autonomy over the scope of the mission depends mainly on the capacity of the battery and the overall aerodynamic efficiency, including the propellers, the body, the payload assembly, and all of their interactions. All this in compliance with the laws of mechanics of flight to which are added a number of safety rules.
Other external factors also affect the autonomy of a drone. This includes weather conditions that, when unstable, result in gusts which will alter the nominal operation of the drone, especially if its design has not included robustness against these constraints. It is also the variability in the profile of the mission, whether by the different loads to carry, or by the more or less steep variation of phases of acceleration, full speed and stationary flight.
Finally, missions where the motion is carried out in swarm have the advantage of being able to take advantage of wake or lift interactions, as do the migratory birds, to drastically reduce energy consumption and increase the travelled distance.
Civilian and military missions conducted by swarms of drones
Swarm missions numbers are currently increasing in both the civilian and military sectors. According to recent studies, approximately 30% of civilian missions and 50% of military missions could use this principle of flying in formation.
Whether during a coastal surveillance mission, where the areas to be covered exceed 100 km² and where flying in swarm promotes the achievement of the mission in a single operation, or whether it is in the military field, in particular when performing reconnaissance missions in hostile terrain, all demonstrate the ability to operate more effectiently when in a swarm.
Thus the V flight formations, typically for fixed wing drones, or the close line flight formations, more likely for rotary wing drones such as quadcopters, lead to very significant potential gains and are illustrated by the fact that each new drone that enters the swarm lowers the consumption of the whole. Thus, a rotation system in the organization of swarm will make possible to share uniformly the benefits obtained.
The aerodynamic optimization of the drone swarm will also generate the appearance of specialized drones in the case of certain missions. So can we imagine a drone leader and supervisor in charge of trailing in its wake, with the greatest efficiency, a troop of drones that would operate a specific mission once arrived at the place of intervention. The drone leader and supervisor would remain static during the operation then will ensure the way back by bringing the same overall aerodynamic efficiency.
Finally, let’s not forget that only two drones are enough to form a swarm.
Aerodynamic simulations and innovations
The use of CFD (computational fluid dynamics) simulation allows the optimization of development and design by analyzing the air flows around drones and the wall forces they undergo. Reduction of excessive drag zones, turbulence control, determination of sensitivities to different flight cases, prediction of upwash-type upcurrent zones, and the adjustment of position and incidence during swarm flight are key factors that will push the limits of performance well beyond the current level.
Given the aeronautical character of air drones, and therefore the aerodynamic implicit culture, it is quite surprising to observe some drones, especially in the field of logistics, carry loads absolutely anti-aerodynamic, such as cubic package, without any precautions with regard to the constraints that this generates, particularly on drag and therefore on energy autonomy. Aerodynamic innovation and simulation can remedy this by ensuring the development of lightweight variable geometry devices allowing profiling around the load to lower the drag coefficient.
Beyond the aerodynamic optimization of the drone itself, the future will see the development of the digital twin of the swarm in which the aerodynamic optimization of the drones positioning will play a fundamental role, paving the way for a new era in energy optimization of drone travelling.
