In Association with nVent
Optimising thermal management in UAVs and RAS
Unmanned aerial vehicles (UAVs) and robotics and autonomous systems (RAS) pack powerful electronics into tight spaces, and keeping these systems cool in harsh environments is an increasingly critical engineering challenge.
UAVs and autonomous robots require processors, sensors, and power electronics to operate effectively, but all that computing power packed into drones or robots produces intense heat. This high-density packaging of electronics means thermal management is mission-critical, as vehicles will be rendered useless if components overheat.
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UAVs also often venture into extreme environments, from hot deserts to high-altitude cold air, so their thermal designs must accommodate this range. According to Matt Tarney, Global Vertical Growth Leader for aerospace & defense at nVent SCHROFF: “High external temperatures can further contribute to internal heat, accelerating battery degradation and causing component failures, whereas extreme cold can also reduce battery efficiency and other mechanical component performance.”
Altitude is another factor, as air at high elevation provides less convective cooling, causing electronics to run hotter for a given power level. In high-altitude operations, reduced air density results in less efficient heat transfer, leading to elevated temperatures within the equipment. Engineers must account for this by derating components or enhancing other cooling methods when UAVs fly high.
Beyond temperature, contaminants pose additional challenges. Dust, sand, and moisture can infiltrate cooling pathways. Tarney notes: “Moisture and debris can damage electronics if cooling relies on open or vented enclosures as dust and moisture ingress increases.” This means that sealed enclosures and filters are often necessary to protect sensitive circuits.
Designing for ruggedness: MIL Specs and SWaP-C
Thermal management for UAVs/RAS must consider shock, vibration, and other environmental stresses common in military or industrial applications.
“Thermal management systems should be designed according to MIL-DTL-901E (addressing shock and thermal robustness) and MIL-STD-810F for vibration resistance,” Tarney explains. Compliance with these MIL specs ensures that heat sinks, cold plates, and enclosures stay effective under jolts, G-forces, and constant vibration.
“Size, Weight, Power and Cost (SWaP-C) must also be factored into the product design as UAV applications will have additional constraints due to the system’s compact layout and load capacity.” This often results in designers favouring passive cooling, which adds minimal weight and requires no power, and carefully choosing materials that maximise heat transfer per unit mass. SWaP considerations are a driving force behind innovation in high-efficiency heat spreaders, lightweight heat exchangers, and multi-function structures that reduce weight.
Material selection is one way to meet both MIL standards and SWaP goals. For example, using high thermal conductivity coatings or alloys such as chem film coatings on aluminium can improve heat dissipation without bulky parts. Passive solutions, such as conduction to the airframe or radiation, are preferred for their simplicity and zero power draw. Active solutions are only used when necessary for high-heat devices.
Adapting to different cooling needs
Cooling strategies must be adapted to the needs of the component. High-performance processors and AI computing modules can draw hundreds of watts, so they often require more active cooling techniques such as forced air or liquid cooling. Engineers may use heat sinks with fans, heat pipes, or miniature liquid cooling loops to pull heat away from a UAV’s central processor under heavy computational loads.
In contrast, many sensors and avionics modules generate less heat, which passive cooling can handle, but are more sensitive to environmental conditions. This could mean mounting sensors away from hot electronics, using thermal interface materials to minimise temperature swings, or thermally insulating the sensor from the rest of the system. Sensing elements must remain within their optimal temperature range for accuracy and longevity, even if it means giving them their own dedicated cooling strategy separate from high-power processors.
Innovative solutions: The HTS Card-Lok
The Card-Lok (wedge lock) is a clamp that secures a circuit board inside a chassis and facilitates heat flow into the chassis sidewall/cold wall. The HTS series is a next-generation design that securely holds the PCB in place in rugged, heavy shock, and high vibration environments while also being designed to meet SWaP-C requirements.
What sets the HTS Card-Lok apart is its sawtooth-shaped profile, which improves thermal contact. This serrated profile provides a continuous and uniform surface along the PCB/heat frame and the cold wall, allowing heat to flow almost directly out of the board into the chassis wall. By reducing gaps and thermal resistance, the HTS achieves up to 15% improved thermal performance compared to similar-sized traditional wedge locks.
Conclusion
Thermal management engineers face many challenges. They must dissipate large heat loads in confined spaces, withstand extreme environments, adhere to ruggedness standards, and do it all under tight SWaP-C constraints.
Success comes from a holistic approach, combining robust design, smart cooling strategies tailored to each component, and proactive measures such as simulations and optimised layouts. By focusing on efficiency, designers can extend mission durations and device longevity.
Innovative solutions such as the HTS Card-Lok accelerate thermal performance within SWaP-friendly designs. Armed with these best practices and new technologies, engineers are better equipped to conquer thermal challenges and keep unmanned systems operating reliably in any environment.
To find out more, download the whitepaper below
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AI, Autonomous Vehicles, and the Heat Challenge
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