RuAviation

At UMEX 2026 in Abu Dhabi, United Engine Corporation (UEC, part of Rostec) presented a 500 kW hybrid power unit (HPU) demonstrator developed by UEC-Klimov.

The demonstrator, built around the VK-650V turboshaft engine, is positioned as a fully matured technology platform for next-generation unmanned aerial vehicles (UAVs). It reflects the outcome of several years of focused work on aviation hybrid-electric propulsion. In this architecture, the VK-650V serves as the primary energy source driving an electric generator, while thrust is produced exclusively by electric motors.

The demonstrated configuration corresponds to one of the two fundamental hybrid propulsion architectures used in aviation: parallel and series. In a parallel architecture, the internal combustion engine and the electric machine are mechanically coupled via a common shaft. The electric machine operates bidirectionally, providing supplemental power during takeoff and climb, or switching to generator mode to recharge onboard batteries during lower-demand flight phases.

In a series architecture, energy sources and propulsion motors are decoupled mechanically. One or more electric propulsion motors are powered simultaneously by battery packs and by an electric generator driven by a thermal engine. During takeoff and climb, both sources cover peak loads. In cruise, the thermal engine supplies power to the motors and can recharge the batteries. In the event of a thermal engine failure, stored battery energy preserves the ability to perform an emergency landing.

At the early stage of HPU development in the early 2020s, the VK-650V engine had not yet entered production. Its preliminary design phase began in Q3 2019. Nevertheless, a demonstrator was assembled as early as Q1 2020, enabling integration of an engine mock-up into the hybrid system for initial performance assessments and layout studies. Completion of VK-650V certification in January 2025 significantly reduced technical and schedule risks for further HPU development and validated the selected architecture.

According to Mikhail Shemet, Director for Advanced Programs and Chief Designer at UEC-Klimov, the five-year R&D effort has now been completed. The result is a hybrid power unit demonstrator that successfully passed bench testing and confirmed the adopted engineering solutions. As part of the program, a 35 kW auxiliary power module and a 25 kW high-power battery module were also developed.

“Driven by the rapid growth of heavy unmanned platforms, we see strong momentum in hybrid and electric propulsion. The systems presented are a timely solution for future UAVs. We are already observing strong interest from both Russian and international unmanned aircraft developers in the hybrid power unit, the power module, and the battery system,” UEC’s press service quoted him as saying.

Finalization of the HPU architecture required detailed validation of the electrical subsystem at the level of individual functional modules. Within the demonstrator, the battery module is designed to compensate peak loads and stabilize the energy balance during transient flight regimes.

Components of the Aircraft Energy System:

• VK-650V gas turbine engine
  Output: 500 kW (as part of the HPU)
  Function: Drives the electric generator
  Role: Primary energy source
• Electric propulsion motors
  Output: —
  Function: Thrust generation
  Role: Operate in conjunction with the generator and battery system
• Battery module
  Output: 25 kW
  Function: Peak load compensation
  Features: Immersion cooling, redundant control system, active cell balancing
• Auxiliary power module (piston engine–based)
  Output: 35 kW
  Function: Supplemental electrical power
  Features: Operating temperature range −40 °C to +55 °C (−40 °F to +131 °F), enhanced autonomy

The piston engine–based power module can be considered an optional auxiliary source of electrical power within the HPU. UEC notes that it serves as an efficient alternative to battery packs and is intended to supply electric propulsion systems for multirotor UAVs and specialized ground platforms. It can also be used as a standalone gasoline generator for electrical power production.

Its integration expands the range of operating scenarios in which the hybrid system maintains autonomy and resilience, including missions with limited battery recharging capability. Combined use of the battery module, auxiliary power unit, and gas turbine generator forms a distributed energy architecture, allowing flexible allocation of power sources depending on the flight phase.

The HPU architecture showcased in Abu Dhabi is primarily aimed at heavy UAVs, tiltrotor aircraft, and VTOL platforms, where range, endurance, and multi-regime operability are critical. Modularity and a combined power distribution concept enable scaling across different vehicle classes and integration into new aircraft programs. Use of the VK-650V engine and domestically developed electrical modules reduces reliance on foreign suppliers, establishes a foundation for further hybrid-electric development, and enhances the engineering autonomy of heavy unmanned platforms.