Horizontal Stabilizer Trim Actuation
project name

Horizontal Stabilizer Trim Actuation

For a Captive Carry, Multi-Purpose Vehicle


Ingenium Aerospace designed, developed, and manufactured a redundant linear electromechanical actuator (EMA) for use as the flight control actuator (FCA) for the WhiteKnight2 (WK2) multi-purpose vehicle.

CaseStudy8Problem Statement
The WK2 utilizes an “open architecture” design, and is planned for multi-purpose use in applications such as zero-g aircraft to support passenger training and microgravity science flights as well as the ability to handle missions in high-altitude testing. This vehicle is also capable of launching payloads and is the captive carry vehicle for SpaceShip2 (SS2). Ingenium Aerospace was asked to develop a highly safe flight control actuation system to provide horizontal stabilizer control functionality for the WK2 Vehicle. This system had various critical requirements with safety level equal to or greater than that of traditional commercial aircraft. The customer also requested commonality to the SS2 to keep cost down.

Ingenium Aerospace recognized that a methodical approach to requirements definition, and analysis, coupled with a unique top level actuation architecture were keys to success.   The Ingenium team worked closely with the customer to develop all the requirements and fully understand the safety needs of this vehicle. The system hazard safety assessment (SHSA) made clear that a unique architecture would be needed to achieve the desired safety level. Ingenium designed, developed, qualified and produced the system that meets these needs. This system is electrically and dynamically simplex, however the actuator is structurally redundant, such that no single point failure would allow structural separation of the actuator and the vehicle. The system utilizes the following common components with the WK2 Vehicle; brushless DC (BDC) motors, resolver commutation and rotary variable differential transducers (RVDT’s), no-back modules and gearboxes. The gear ratios similar between SS2 and WK2.

Results & Outcome
Ingenium Aerospace qualified and delivered a unique Horizontal Stabilizer Trim Actuation (HSTA) product for this vehicle. The units are flying successfully and performing the HSTA function. The commercial HSTA system meets it objectives and has been flying flawlessly for years.   The utilization of common components across platforms continues to keep the costs as low as possible for this low rate production vehicle.