SAE - ARP94910
Aerospace - Vehicle Management Systems - Flight Control Design, Installation and Test of, Military Unmanned Aircraft, Specification Guide For
|Publication Date:||1 December 2012|
This document establishes recommended practices for the specification of general performance, design, test, development, and quality assurance requirements for the flight control related functions of the Vehicle Management Systems (VMS) of military Unmanned Aircraft (UA), the airborne element of Unmanned Aircraft Systems (UAS), as defined by ASTM F 2395-07. The document is written for military unmanned aircraft intended for use primarily in military operational areas. The document also provides a foundation for considerations applicable to safe flight in all classes of airspace.
Vehicle Management Systems
UA VMS include all components and functions used to sense vehicle position, velocity, speed, inertial attitudes, rates and accelerations, heading and altitude, to generate flight path commands and to control aircraft force and moment producers to satisfy these commands. Guidance and navigation elements and functions of the VMS normally control aircraft altitude, airspeed, heading, attitude, aerodynamic or geometric configuration, and structural modes, including commands received from a remote operator.
The document recommends requirements for the general performance, design, test, development and quality assurance measures for the flight control of remotely controlled, augmented and autonomous UA. At the system performance level the document employs a functional emphasis. It recommends a practice for specifying the levels of flight control capability, particularly fault accommodation after failures, required for UA of differing size, function and operational strategy. It defines the boundaries of UA flight control to include hardware and functionality not typically considered core flight control elements in a manned aircraft, such as navigation sensors and flight path and engine power command generation. It also guides the specification of the flight control Interfaces with all other systems and subsystems of the vehicle.
At the subsystem and component levels the document addresses those aspects of hardware design that impact system performance. Among components included are the inertial sensors, global positioning sensors, air data sensors, test devices, actuators, electrical power sources, hydraulic power sources, and signal transmission lines within the vehicle and dedicated to flight control.
Because of the wide range of UA size and capability UA VMS hardware design architectures differ widely. At the system level the document avoids any hardware emphasis and does not recommend particular hardware design approaches. The document provides guidance for the specification of elements of the UA vehicle only and not the other elements of the UAS such as the Control Station (CS). For example, it addresses the integration with the up-link and down-link of the command loop but not the specification of these links. Also excluded are aerodynamic surfaces, engines and engine control systems, rotorcraft rotors and fire control devices. The requirements for UAS operation in non-segregated airspace include factors such as See and Avoid and other functions, beyond those considered for manned military aircraft. These requirements are still evolving and are beyond the scope of this document.
This Aerospace Recommended Practice (ARP) is closely related to the Aerospace Standard AS94900, for the flight control systems of manned aircraft and follows a similar format.
Best Practices and Procuring Activity Approval
This ARP is intended as a guide to standard practice and is subject to change to keep pace with experience and technical advances. Most of the technical concepts and approaches covered by the document represent industry "best practice". They are based on sound and proven engineering practices and have demonstrated successful production experience. Others require specific approval from the procuring activity before use. This recommendation for approval is not intended to inhibit their use; but rather to ensure that the prime contractor has fully investigated their capability to perform reliably and to be sufficiently durable under the required conditions and that the prime contractor can present substantiating evidence for approval before the design is committed to.