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LVDT Applications that are Used in Helicopters

Wednesday, November 24, 2021

At Sentech, our custom-designed, and cost-effective LVDTs and RVDTs are unparalleled in helicopters. LVDTs and RVDTs are used in applications involving cockpit controls, engine valves, actuator position, and main rotor position. With that in mind, here is a list of some of the most important terms to know when dealing with Helicopter position sensors. 

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LVDT Applications in Helicopters

  • Cockpit Controls: The cockpit controls involve collective pitch control, cyclic pitch control, throttle control, and tail rotor control. All four of these determine the activity of the helicopter and where the pilot sits to fly it. 
  • Pedal Position: This is imperative to flying the helicopter. A change in pedal position changes the angle of the tail rotor and offsets the torque. In other words, pushing the pedal turns the helicopter. 
  • Autopilot Position: There are four different autopilot position options. The most basic option is the single axis which keeps the helicopter from rolling. A two-axis controls the roll and the pitch, a three-axis controls the yaw, and the four-axis introduces the automatic hover feature.
  • Main Rotor: The main rotor is the combination of several rotary wings that generates the aerodynamic lift force to support the weight of the helicopter. 
  • Actuator Position: The actuator position controls the main rotor pitch on a helicopter. 
  • Control Augmentation Stability: This is another type of automatic flight control system that will move the aircraft control surfaces to damp unacceptable motions to automatically stabilize the aircraft. 
  • Power Drive Unit: The power drive unit is used to convert electrical or hydraulic power into mechanical motion. 
  • Engine Valves: Engine valves allow for letting air and/or fuel into the cylinders to be combusted. 

Cockpit Controls Overview


At the controls of those rapidly spinning blades is a trained aviator, who must be able to keep the helicopter steady in tight spaces and go on life-saving missions that no commercial airplane could accomplish. Thus, it’s important to understand how the set of four controls work both in tandem and simultaneously in the cockpit of a helicopter.

1. Cyclic Control

Rising from beneath the front of each pilot’s seat, the cyclic stick controls the main rotor to dictate the direction and movement in-flight, during a hover, and lateral movement. It also helps to fine-tune the helicopter’s position.

2. Collective Pitch Control

Located on the left side of the pilot’s seat, the collection allows the pilot to make changes in the angle of the main rotor blades. The pitch control exposes or decreases the angle of the main rotor blades. This allows the helicopter to ascend or descend.

3. Throttle Control

Usually mounted as a twist grip on the collective control, the throttle controls the power output of the engine. The throttle setting must be adjusted to keep the rotor speed to maintain lift during the flight.

4. Anti-torque Pedals/ Tail Rotor Control

Similar in function and location to a commercial airplane, the anti-torque pedals control the tail rotor blade pitch and point the nose of the aircraft to control the heading or tendency to twist (yaw) of the helicopter.

Trust in Sentech’s LVDTs and RVDTs For Your Helicopter

As stated above, LVDTs installed on commercial helicopters have multiple applications. These LVDTs emit electrical signals and monitor the hydraulic actuator rod to change the rotor pitch and angles responding to the pilot’s commands.


On the other hand, RVDTs are the ideal solution when angular position feedback is required. For example, closed-loop control systems route the pilot’s flight control commands through the onboard computer through a mechanical motion of the stick control. The RVDT sensor stands between the pilot’s command and the system output by keeping moving parts from contacting stationary surfaces. Thus, both LVDTs and RVDTs offer significant advantages to the controls of helicopters!

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Key Takeaways:

  • LVDTs have multiple applications on helicopters such as cockpit controls, pedal position, main rotor, engine valves, and more. 
  • Cockpit controls include a set of four controls working in tandem and simultaneously in the cockpit of the aircraft. 
  • While LVDTs emit electrical signals to change the rotor pitch, RVDTs are the ideal solution for angular position feedback. 

Contact Sentech For Helicopter Position Sensors Today

If you are interested in learning more about helicopter position sensors, give us a call! Sentech products are the best performing and most cost-effective solutions to any manufacturing or monitoring problem. We offer high-quality Linear Variable Displacement Transducers (LVDTs), Rotary Variable DIfferential Transducers (RVDTs), FASTAR sensors, HYDRASTAR sensors, signal conditioners, and solenoids. Contact us today!


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