An Introduction to Aircraft Actuators: How They Enable Flight Control

 

Aircraft Actuators

What are Aircraft Actuators?

Aircraft actuators are electro-mechanical devices used to control and maneuver different flight control surfaces on an airplane. They are an essential component of a plane's fly-by-wire control system and enable pilots to command wing flaps, rudders, elevators and other critical control surfaces through inputs to the flight controls in the cockpit. Different types of actuators work to precisely position control surfaces based on electronic signals from the aircraft's flight computer.

Types of Actuators Used in Aircraft

There are a few main types of actuators employed in modern aircraft:

Hydraulic Actuators

Hydraulic Aircraft Actuators remain one of the most commonly used actuator technologies. They utilize high-pressure hydraulic fluid to produce powerful linear or rotary motion. Hydraulic actuators are robust and reliable, providing the muscles needed to manipulate heavy control surfaces. Older aircraft without fly-by-wire typically relied solely on hydraulics for primary flight control actuation.

Electro-Hydrostatic Actuators

Electro-hydrostatic actuators (EHAs) are an evolution of hydraulic technology. They replace hydraulic pumps and valves with electric motors and pumps, controlled electronically. This has the benefit of eliminating unnecessary hydraulic lines and reducing weight. EHAs are more precisely responsive than hydraulic actuators alone and work well for secondary flight control functions.

Electromechanical Actuators

For non-critical functions where weight is a premium, aircraft may instead use lighter electromechanical actuators. These act directly via electric motor rather than hydraulics. Common applications include movable wing slats, spoilers and slats. Electromechanical actuators reduce fluid requirements and eliminate leak points at the cost of raw power output.

Piezoelectric Actuators

Piezoelectric actuators harness the property of certain crystals to generate a voltage when compressed. They can be integrated into smart structures for on-wing control surface modulation. Still mainly in development, piezoelectric actuators promise ultra-precise flight control capabilities with minimal weight and complexity penalties.

How Aircraft Actuators Work

Regardless of the specific technology, all aircraft actuators function through the precise conversion of electrical control signals into movement. Here's a brief overview of the basic process:

1. The pilot manipulates flight controls like the control yoke, rudder pedals or control stick in the cockpit.

2. Sensors relay the pilot's inputs to the fly-by-wire flight computer as electrical signals.

3. The flight computer processes these signals and determines how flight control surfaces need to be positioned for the desired maneuver.

4. Electronic commands are then sent to individual actuators positioned at each control surface.

5. Based on the electronic command, the actuator mechanically moves the control surface via linear movement, rotary motion or hydraulic pressure in small, precisely calibrated increments.

6. Position feedback sensors on the actuators and control surfaces continually relay surface positions back to the flight computer to ensure alignment with the pilot's demands.

7. The process repeats fluidly and continuously to maintain stability and optimized lift/drag characteristics throughout all phases of flight.

Actuator Redundancy for Safety

Commercial and military aircraft require the highest levels of safety, so aircraft actuators employ redundant configurations. Multiple actuators may work in parallel to move a single control surface. If one actuator fails, the others can take over the full load. Digital signaling further enhances reliability by allowing actuators to electrically communicate diagnostic data for proactive maintenance consideration. Together, these measures help ensure command over vital control systems even in component failure scenarios.

A Key Enabler of Modern Flight Control

As technologies evolve from mechanically-linked controls on early aircraft towards highly computerized fly-by-wire flight management computers, aircraft actuators play an indispensable role in translating signals into movement. Their precision actuation allows commercial and military aircraft alike to attain exceptional levels of responsive handling, stability augmentation and fly-by-wire maneuverability. As the building blocks enabling digital flight control, actuators are central to continuing aviation's advancement well into the future.

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Ravina Pandya, Content Writer, has a strong foothold in the market research industry. She specializes in writing well-researched articles from different industries, including food and beverages, information and technology, healthcare, chemical and materials, etc. (https://www.linkedin.com/in/ravina-pandya-1a3984191)