At the last MAKS-2021 air show, the Russian United Engine Corporation (UEC) presented a number of promising developments in different directions. One of the most interesting exhibits of its stand was a model of a hybrid power plant (GSU) being developed for implementation in aviation. It is expected that such a GSU will be able to find application in various aircraft projects and provide high performance.
Hybrid plants based on a gas turbine or piston engine coupled with various electrical components have a number of important features and advantages over traditional systems. These advantages can be used in various fields, incl. in aviation. Currently, in several countries at once, the development of aviation GSUs of different composition is being carried out. Some projects have already been brought to bench and field tests.
In August 2020, the Russian UEC launched a similar project. JSC UEC-Klimov was appointed the lead developer. The goal of the new project is to create a promising sequential HSS circuit with a capacity or 500 kW. This installation will be based on the latest VK-650V turboshaft engine.
By now, the early stages of the project have been completed and the general appearance of the installation has been determined. In addition, a mock-up was made, shown at the recent MAKS-2021 show. In the near future, there will be a demonstration model for bench testing. Over the next years, it will reach its maximum capacity and will allow the transition to new stages.
According to the UEC, in 2022, a demonstration sample of the GSU should show a power of 150 kW and ensure the verification of the laid down solutions. Then it will be finalized, and tests are planned for 2023 with the achievement of the design power of 500 kW. Based on the results of these activities, in 2024, experimental design work will begin to create a full-fledged GSU for use on aircraft. It is planned to be completed in 2028.
The UEC has already identified the areas of application of the promising GSO. This system can be used on airplanes for local lines, on light multipurpose helicopters and on UAVs weighing up to 8 tons. It can also be used on various vertical takeoff vehicles, on promising "air taxis", etc. A similar system for boats and ships will be developed on the basis of the aviation GSU. It will develop a capacity of 200-250 kW.
At MAKS-2021, a model of the GSU was demonstrated in a configuration for a helicopter-type UAV with four main rotors. The units of the installation were placed on a stand simulating a similar product. This approach to the display makes it possible to assess the size of the GSU and the features of its placement on the aircraft.
A compact gas turbine generator set based on an existing engine of sufficient power was placed on a conventional fuselage. A battery pack and power electronics units were installed next to it. On the "wings" were placed four electric motors with rotors. All components of the GSU were connected by cables.
The layout reflects the general scheme and composition of the promising GSU in relation to the quadrocopter. Aircraft of other schemes and classes will receive installation of a different composition and architecture. So, it is possible to use a different number of electric motors, different battery configurations, etc.
The principles of operation of the new GSU are quite simple. A turboshaft engine with a generator generates electrical power for the power electronics. The latter is responsible for controlling the electric motors responsible for the flight, and also recharges the batteries. The operating modes of the installation from the UEC have not yet been specified.
Difficulties and advantages
A hybrid plant based on a turboshaft engine and electrical components has a number of distinctive advantages over traditional systems. At the same time, there are also disadvantages of various kinds. Obviously, the correct approach to the design of the GSU itself and to the selection of the aircraft for it will allow you to get the maximum return with minimal disadvantages.
Gas turbine systems include a number of dissimilar components, which is why it differs from traditional gas turbine systems in greater complexity and cost. In addition, the hybrid installation has a larger total volume and mass, which imposes restrictions on the development of the carrier aircraft. At the same time, GSU units do not need a rigid mechanical connection with each other, and they can be spaced across the available volumes, which simplifies the layout of the aircraft.
Hybrid plants can show high fuel efficiency. To do this, the turboshaft engine must operate at optimal modes that give minimum fuel consumption, and the control systems are entrusted with the task of correctly distributing electricity between the motors and batteries in accordance with the current flight mode. At the same time, other characteristics are also improved: the resource grows and harmful emissions are reduced.
The flight of the device with the GSU is carried out by electric motors controlled by electronics. This allows you to more efficiently maintain the required mode of operation, as well as quickly change it taking into account changing conditions. In particular, it will ensure a quick release to maximum power.
Depending on the composition and management principles, the GSU is theoretically capable of operating in several modes, incl. without the use of a turboshaft engine - only due to the batteries. This mode will increase reliability and safety: if the main engine and generator fail, the aircraft will be able to continue flying.
Plans for the future
Thanks to one or another advantage, hybrid power plants of different architectures can find a place in aviation and push back systems of the traditional kind. GSOs are of interest in the context of the further development of manned and unmanned aircraft and helicopters. However, while one should not expect that in a reasonable time they will be able to completely displace other options for power plants.
The potential of the GSO naturally attracts developers and customers from different countries, and since last year the Russian industry has been closely engaged in this topic. The first works have already been carried out, general principles of promising projects have been formed and future areas of their application have been identified. In addition, a model of the future product is shown and events for future years are announced.
Development work on a 500 kW power plant based on the VK-650V engine will take place in 2024-28. Thus, already in the middle of the decade or at the beginning of the second half of it, one can expect the appearance of the first full-fledged aircraft projects for the domestic aviation GSU. Projects for the introduction of its marine modification will also have to appear.
It is not known what the aircraft and boats with a hybrid power plant will be. However, it is clear that this direction has great potential and allows you to get very interesting opportunities. It should be developed with an eye to practical use. This is exactly what the UEC has been doing since last year - and it is already ready to show the first results.