Video Details 787 Autopilot Turbulence Mitigation
A video breakdown posted online details how the Boeing 787's autopilot uses its flaperons for active turbulence mitigation. The system processes data from multiple sensors, including airspeed, inertial navigation, and accelerometers, to execute real-time flight control algorithms. The demonstration was praised by observers as a showcase of the stability achieved by commercial avionics engineers.
- The system, officially known as the Vertical Gust Suppression System, is a feature of the 787's fly-by-wire flight controls and is designed to counteract vertical gusts, which are a primary cause of passenger discomfort. It complements a separate Gust Load Alleviation system aimed at reducing structural stress on the airframe, particularly the wing bending moment, by automatically deflecting control surfaces. - This technology has its roots in systems developed for military aircraft like the B-2 bomber, which also utilizes active gust alleviation to maintain stability and reduce structural fatigue. While the preceding Boeing 777 featured a system to counteract yaw (side-to-side motion) for a smoother ride, the 787 expanded this concept to actively dampen vertical (up-and-down) motion. - The system relies on a network of sensors, including accelerometers and gyroscopic sensors, that detect changes in the aircraft's angular velocity and vertical movement. These sensors feed data to the flight control computers, which execute algorithms to command rapid, subtle adjustments of the flaperons and elevators to counteract the turbulence-induced motion before it is fully felt in the cabin. - For the stretched 787-10 variant, an additional system called the Flaps Up Vertical Mode Suppression System (F0VMS) was introduced. This system specifically controls the elevators to counter aeroelastic flutter tendencies that are more pronounced due to the longer fuselage, a novel approach for a commercial airliner that avoided a heavier wing redesign. - The control inputs are generated without direct pilot commands and the yoke or pedals do not move, reducing pilot workload during approach and cruise in turbulent conditions. This functionality is part of a broader suite of computerized control laws that required extensive special certifications covering the interaction between the electronic flight controls and the aircraft's structure. - Beyond the active control system, the 787's design inherently helps mitigate turbulence through its composite wings, which are longer, thinner, and more flexible than those on previous generation aircraft. These wings are designed to flex upwards by as much as 25 feet, absorbing and dissipating gust energy that would otherwise be transferred to the fuselage.
