DC Motors for Missile Fin Actuation Systems

Missile systems require precision control to navigate and intercept targets while being exposed to extreme environments, including wide temperature ranges and heavy vibrations. Within the larger missile system is the missile fin actuation system, which oversees the movement and positioning of the missile fins (also known as control fins) in response to the steering commands from the flight computer. Miniaturized, lightweight technologies are essential to improving the maneuverability of these mission-critical systems, as when a missile is launched, these control fins position the trajectory of the missile towards the intended target.

DC Motors for Controlling Missile Fin Movements

Miniaturized, lightweight motors are essential to improving the maneuverability of mission-critical systems. DC motors are especially ideal for controlling missile fin movements to achieve improved aerodynamic stability and trajectory. Missile control applies to the canards, wings, and tail control:

  1. Canards control is primarily employed for longitudinal control during missile maneuvering. This is one of the most used missile controls, especially on short-range air-to-air missiles.
  2. Wings control, while not used as often as in the past, is one of the earliest types of missile control and focuses on the maneuverability of the wings with as little body motion as possible.
  3. Tail control is one of the most common types of missile control for longer-range air-to-air missiles and surface-to-air missiles. This ensures that the tail of the missile can deftly maneuver at high angles.

An Overview of Missile Fin Actuation Systems

The typical missile fin actuation system consists of four actuators, which are equipped with integrated electronic systems that are attached to the outer mold of the missile body. An intelligent rotary missile fin actuator positions the fins (each of which is powered by a DC motor) according to the instructions received from the onboard processor.

Block Diagram of Missile Fin Actuator

Block Diagram of a Missile Fin Actuator System

The actuator system is comprised of two subsystems: the electronic control unit and the electromechanical actuator (Figure 2). The position command signals the electronic control unit, which in turn provides input voltage to drive the electric motor in the electromechanical actuator. Depending upon the speed and torque requirements, the DC motor may be coupled with a gearbox and leadscrew arrangements to actuate mechanical linkages. These linkages control the missile fin and position the missile towards the identified target that is to be destroyed.

Design Requirements for Missile Fin Actuation Systems

Missile systems must operate and perform with precision at subsonic, supersonic, and hypersonic speeds and in grueling conditions. DC motors are designed to drive the fin actuators with optimum performance in such environments. Here are five key performance characteristics of these motors:

  1. Responsiveness. Though this is highly dependent on the type of missile, range, and payload capacity, DC motors typically exhibit responsiveness of torque and high acceleration.
  2. Agility (Form Factor). Optimum motor sizing minimizes weight for improved maneuverability of the missile.
  3. Ruggedness. DC motors are designed with a robust mechanical enclosure and internal components that allow them to withstand mission-critical conditions, including operational and storage temperatures ranging from -40°C to +85°C; relative humidity levels between 40% to 45%; and shocks and vibrations ranging from 100g to 250g @ 15 – 40 msec.
  4. Shelf Life. The lifespan motors in storage are required to last up to 15 to 20 years.
  5. Duty Cycle. DC motors generally operate at 4 to 5 seconds to a maximum of 30 to 40 seconds for fin actuation.

Portescap is a leader in delivering exceptional solutions that are suited for responsiveness, reliability, and motion precision. Our designs provide optimum torque and efficiency in compact and lightweight envelopes capable to operate in critical environmental conditions. We take pride in supporting customers in the design/selection, integration, and validation of DC motor technology to deliver optimum performance for any application – including missile fin actuation systems.