How the Replacement of Centralised Hydraulics in Aerospace Can Create Transformative Change

Aeroplane wing

Share this post

Centralised hydraulic systems have long been the norm for control and actuation in aircraft. Critical flight control systems such as rudders, elevators, and ailerons rely on these heavy systems. Theoretically, some of the drawbacks associated with centralised hydraulics can be alleviated by moving to distributed hydraulic systems, however, this has proven difficult in practice.

What Are Centralised Hydraulic Systems?

Many aircraft rely on centralised hydraulic systems to actuate components such as flaps, brakes, and landing gear. These centralised systems contain hydraulic pumps, from which hydraulic pressure goes to multiple subsystems within the aircraft. These subsystems contain all the hydraulic control equipment required for proper operation. Centralised hydraulic systems have layers of redundancy built into them to ensure that a loss of pressure or another fault does not affect the most critical systems.

Centralised hydraulic systems require a lot of piping to connect and drive all hydraulic components across the hydraulic subsystems around an aircraft. The amount of piping needed can add up to over a kilometre on certain aircraft, and the whole system can weigh over two tonnes, which has a significant impact on the energy efficiency of aircraft.

What Are Distributed Hydraulic Systems?

Distributed, or decentralised, hydraulic systems are simply a collection of self-contained hydraulic subsystems. Each hydraulic subsystem has its own set of hydraulic pumps and hydraulic control equipment. These subsystems operate independently of each other. Independent subsystems allow for fault isolation, as a fault in one subsystem will not affect other subsystems.

Distributed systems allow for weight reduction, as smaller hydraulic pumps can be used for localised hydraulic control. These smaller pumps also use smaller diameter piping and need less of it for the localised subsystems, resulting in weight reduction and increased energy efficiency. This can come at the cost of complexity, as distributed hydraulic systems can be more complex to manage and operate than centralised hydraulic systems.

Difference Between Centralised and Distributed Hydraulic Systems

In summary, centralised and distributed hydraulic systems differ on the following points:

  • Centralised hydraulic systems contain a single source of hydraulic power, distributing those hydraulics across the entire system, while distributed systems consist of subsystems, each with its source of power generation.
  • Centralised systems tend to be cheaper, while distributed systems are more expensive to install and can be more complex.
  • Centralised systems are very heavy, due to the amount of added piping required. Distributed systems are generally much lower weight, due to smaller components, and smaller diameter piping.

Domin takes a Different Approach to Enable Transformative Change

There has been a concerted effort to move from centralised to distributed hydraulic systems in aerospace, driven by the potential for weight reduction, improved fault isolation, and potential energy efficiencies. However, the current technology behind distributed hydraulic systems has shown limited gains. 

At Domin, using cutting-edge tools like metal additive manufacturing, we have developed two pieces of technology that are driving transformative change in the aerospace industry. The first is our high-speed control valves, which are lightweight and efficient with world-leading precision and the second is our radial piston pumps, which are ultra-compact and power-dense, their low inertia enables high levels of controllability. 

By combining these technologies, we have developed micro-electrohydrostatic actuators (mirco-EHAs) that offer all the benefits of hydraulics with the integration and control of electromechanical systems, opening the door for distributed hydraulic systems for aircraft. This leads to opportunities for further innovations, such as reduced wing sizes, lower fuel usage, and longer range. Our use of modern electronics also opens the door for condition monitoring, real-time fault and anomaly detection, and more.

With our innovative approach to hydraulic design by utilising modern technologies such as additive manufacturing and onboard electronics, we can make systems significantly smaller than existing designs, and improve performance. Domin’s electrically signalled distributed hydraulic actuation systems offer a potential 50% weight reduction per aircraft, which will enable the push for ground-breaking energy efficiencies and More-Electric aircraft. 

Set New Standards for Your Organisation

Contact our sales team to learn more about Domin’s technology solutions.