Advanced Scout Helicopter (ASH) Fly-by-Wire Flight Control System Preliminary Design. Volume I. System Design and Analysis

摘要

This preliminary design study was conducted to assess the payoffs in applying fly-by-wire and other advanced flight control concepts to the anticipated Advanced Scout Helicopter (ASH). The study compares the advanced concept systems with a dual mechanical flight control system in the following areas: handling qualities, reliability, maintainability, availability, durability, survivability, EMP/EMI/lightning tolerance, cost, and weight. The candidate vehicle for the study was the Medium Utility Transport (MUT) as defined in document USAAMRDL-TR-75-56A (gross weight 9,544 lb and useful payload 960 lb). The selected fly-by-optics and fly-by-wire candidates employ triplex in-line monitoring for primary controls and triplex cross-channel monitoring for augmentation functions. Both use of a two-axis sidearm force controller with separate collective pitch controls and directional pedals. Processing is digital, using 16-bit microprocessors. A multiprocessor approach is defined to provide hardware separation of the flight-critical primary control functions from noncritical automatic control functions. Rotor control actuators are of an integrated design having triplex electrical control elements with a dual hydromechanical output stage. Both candidates were found to be superior to the dual mechanical system in most respects. The fly-by-optics has a further advantage over the fly-by-wire in EMP/EMI/lighting tolerance, maintainability, and availability. Production acquisition and operation/maintenance costs are similar for all candidates. Further development of fiber optic transducers and interfacing hardware is required to reduce risk for the fly-by-optics candidate.