Linear vs. Rotary Actuators in Aerospace Applications

In countless aerospace systems, actuators are essential for converting energy into precise mechanical movement. Given the demanding performance and reliability standards of flight control surfaces, landing gear, engine components, and the other areas they are commonly implemented, actuators must be carefully selected to balance power efficiency and weight constraints.

Linear and rotary actuators represent the two primary motion categories, each offering distinct advantages based on how they translate electrical, hydraulic, or pneumatic energy into motion. In this blog, we will provide insight into what linear and rotary actuators are, how they respectively operate, and what kinds of aerospace applications they best serve, helping readers determine which option is most appropriate for particular requirements.

Linear Actuators

Linear actuators produce accurate and controlled motion along a straight path, aiding in pushing, pulling, or lifting components with consistency. Electromechanical variants achieve this by using electric motors to drive screw mechanisms. Alternatively, hydraulic and pneumatic models pressurize fluid or air to move a piston within a sealed cylinder.

Advantages and Limitations

Linear actuators serve aerospace assemblies that demand both precision and high load capacity in a straight-line force, accomplishing tasks such as:

• Extending and retracting landing gear
• Adjusting flap positions for lift and drag modulation
• Actuating cargo doors and hatches
• Controlling rudders and elevators

Hydraulic linear actuators are especially effective under heavy loads due to the efficient force transfer of incompressible fluid, although they and pneumatic types tend to be heavier and need supporting infrastructure like pumps, reservoirs, and pressure lines, introducing more maintenance considerations and the risk of fluid leaks or pressure loss. Their single-axis motion also necessitates additional space for full extension, which can be limiting in compact aircraft compartments. Meanwhile, electromechanical linear actuators, while generally more compact and easier to maintain than those subtypes, may not match their force output and are more prone to issues like wear or overheating in continuous-duty applications.

Rotary Actuators

Rotary actuators generate angular or rotational motion, and like linear actuators, their specific mechanical conversion methods also depend on their energy source. For instance, electromechanical rotary actuators typically use gear trains or motor-driven shafts. On the other hand, hydraulic and pneumatic types rely on vane-type mechanisms or rack-and-pinion assemblies, where pressurized fluid or air drives internal components to generate torque.

Advantages and Limitations

Rotary actuators have the ability to deliver continuous or oscillating rotation for high-speed, repetitive operations. They also tend to have a more compact form factor than linear actuators, and their mechanical simplicity can lead to lower maintenance requirements in certain configurations. As such, rotary actuators are regularly employed to:

• Position jet engine components like variable stator vanes
• Operate air inlet guide vanes (IGVs)
• Actuate valves within hydraulic or fuel systems
• Adjust rotor blade pitch in helicopters

In particular, hydraulic and pneumatic variants provide relatively high torque output for their size, making them ideal for applications that seek moderate rotational force without excessive weight. However, rotary actuators do present limitations depending on their type and application. For example, hydraulic or pneumatic variants may be more susceptible to pressure fluctuations, which can impact consistency and control. Furthermore, electric rotary actuators can experience torque ripple and heat buildup during high-demand cycles.

The Choice between Linear and Rotary Actuators in Aerospace Settings

As we have covered, selecting between linear and rotary actuators in aerospace design demands careful consideration of motion type, load requirements, spatial limitations, and environmental conditions. While linear actuators excel at delivering strong, precise push-pull movement, rotary actuators are better suited for compact, high-speed rotational control. Because modern aircraft rely on a wide range of mechanical functions, both actuator types are typically incorporated within a single platform.

There is also growing interest in hybrid actuator architectures that combine linear and rotary motion. Already deployed in some research platforms and specialized military applications, these hybrid designs offer the potential for enhanced multi-axis control, built-in redundancy, and greater adaptability within increasingly compact and complex airframes. Nonetheless, their implementation presents challenges, including added system complexity, higher development and integration costs, and the need for rigorous validation to ensure they can withstand sustained use in aerospace environments.

Rely on ASAP Part Services for Aerospace Actuators

Whether you are seeking actuators or any other aerospace components, having access to dependable and rigorously vetted options is crucial. ASAP Semiconductor is a trusted procurement partner for such requirements, offering countless industry-standard products from leading manufacturers through its specialized platform ASAP Part Services.

By shopping on ASAP Part Services, customers gain the advantage of streamlined fulfillment, competitive pricing, and the confidence that comes with working alongside a distributor committed to quality and compliance. To discuss how else we can optimally serve your procurement needs, reach out to one of our specialists today!