HALE UAVs operated as part of High Altitude Platform Systems (HAPS) enable satellite-like telecommunications and surveillance services at significantly lower cost, with sustained operation between 15,000 and 25,000 meters and mission durations from days to months.
In this environment, flight control depends on electromechanical UAV servo actuators that must deliver precise control authority under conditions no commercial aircraft encounters. PEGASUS addresses these requirements with redundant actuator architecture and stratosphere-qualified solutions such as the PA-RR-340-7-IH with integrated heating.
Stratospheric HALE UAVs are designed for persistent missions above weather and conventional air traffic. Typical programs demonstrate aircraft in the 50–100 kg class with 25–50 m wingspans, powered by solar cells, batteries, or hydrogen fuel cells – and optimized for telecom relay, environmental monitoring, and persistent surveillance.
At cruise altitudes above 20 km, the actuator environment becomes extreme: atmospheric pressure drops below 100 Pa (less than one thousandth of sea level pressure), and temperatures fall below −70 °C (with even lower extremes). Unlike conventional aircraft that pass through these conditions briefly, HALE platforms remain there for days or months, so actuator reliability, precision, and energy discipline become mission-critical.
Key constraints for UAV servo actuators in HALE / HAPS missions (overview):
At ~20 km altitude there is no practical recovery option after flight control failure. The case document is explicit: single-point failure tolerance is not optional – losing a primary flight control actuator can mean losing the aircraft.
PEGASUS redundant UAV servo actuators address this with a dual-channel architecture built around independent brushless motors, separate servo controller boards, and redundant contactless position sensors. If the primary motor or controller fails, the backup system engages automatically – without autopilot intervention and without performance degradation.
The PA-RR-340-7-IH is a redundant electromechanical UAV servo actuator derived from the proven RR340 platform and specifically adapted for stratospheric HALE and HAPS missions.
With a rated torque of 850 Ncm and a positioning speed of 140° per second, the actuator provides the dynamic performance required for primary flight control surfaces operating in low-density air at high altitudes. A sensor resolution of below 0.022° ensures precise positioning accuracy, even under extreme environmental conditions.
To enable reliable operation at temperatures below −70 °C, the actuator integrates a fully redundant heating system designed to stabilize internal components and maintain consistent control characteristics. The heating architecture itself follows the same single-point failure tolerant philosophy as the drive system.
The PA-RR-340-7-IH is not a laboratory concept but a field-proven solution. It has been deployed in multiple generations of HALE platforms over more than a decade of operational experience, supporting persistent stratospheric missions where actuator failure is not an acceptable scenario.
These stratospheric actuators are not a recent concept: PEGASUS has delivered specialized redundant servo actuators with integrated heating for HALE UAV applications for over ten years, with reliable operation across multiple platform generations, from early demonstrators to current 5th and 6th generation production aircraft.
The document also underlines that each HALE platform generation drove incremental improvements in temperature management, power efficiency, and long-duration reliability – resulting in maturity shaped by real stratospheric operation, not laboratory simulation alone.
As telecom providers, environmental agencies, and defense organizations increasingly recognize the potential of HAPS, demand for qualified stratospheric components continues to grow. The case positions PEGASUS as a specialist supplier for this emerging segment with flight-proven technology ready for the next generation of high-altitude platforms.
Stratospheric UAV platforms demand actuator solutions that go beyond standard configurations. Whether torque adaptation, thermal integration, redundancy architecture or system interface requirements – high-altitude missions require precise alignment between actuator performance and aircraft design.
PEGASUS development engineers work closely with aerospace customers to adapt proven actuator platforms to specific environmental and operational requirements.
Based on standardized actuator architectures, customized configurations can be realized efficiently – without compromising reliability, certification pathways or long-term performance. Discuss your HALE or HAPS application with our engineering team and explore how a redundant UAV servo actuator solution can be tailored to your system requirements.
