Flying Qualities is that discipline in the aeronautical sciences that is concerned with basic aircraft stability and pilot-in-the-loop controllability. With advent of sophisticated flight control systems, vectored thrust, forward-swept wings, and negative static margins, the concept of flying qualities takes on added dimensions. In aeronautical literature there are three terms bandied about which are generally considered synonymous. These terms are flying qualities, stability and control, and handling qualities. Strictly speaking, they are synonymous. An early publication by Phillips in 1949 defines flying qualities of an aircraft as those stablity and control characteristics that have an important bearing on the safety of flight and on the pilots' impressions of the ease of flying an aircraft in steady flight and in maneuvers. The specification's stated purpose of application is to assure flying qualities that provide adequate mission performance and flight safety regardless of design implementation or flight control system mechanization. Successful execution of the military mission then is the key to flying quality adequacy. A definition of flying qualities which can be agreed upon by both the USAF and the US Navy is: Flying qualities are those stabilty and control characteristics which influence the ease of safely flying an aircraft during steady and manuevering flight in the execution of the total mission.
Divergence experienced during rolling maneuvers has frequently been referred to as inertial coupling. This leads to a misconception of the problems involved. The divergence experienced during rolling maneuvers is complex because it involves not only inertial properties, but aerodynamic ones as well. The material in this chapter is intended to offer a physical explanation of the more important causes of roll coupling. Coupling results when a disturbance about one aircraft axis causes a disturbance about another axis. An example of uncoupled motion is the disturbance created by an elevator deflection. The resulting motion is restricted to pitching motion, and no disturbance occurs in yaw or roll. An example of coupled motion is the disturbance created by a rudder deflection. The ensuing motion will be some combination of both yawing and rolling that results in coupling problems large enough to threaten the structural integrity of the aircraft.
As spinning is still involved in around 60% of all aircraft accidents (BFU, 1985 and Belcastro, 2009), this aerodynamic phenomenon is still not fully understood. As U.S. and European Certification Specifications do not require recoveries from fully developed spins of Normal Category aeroplanes, certification test flights will not discover aeroplane mass and centre of gravity combinations which may result in unrecoverable spins. This book aims to contribute to a better understanding of the spin phenomenon through investigating the spin regime for normal, utility and aerobatic aircraft, and to explain what happens to the aircraft in terms of the aerodynamics, flight mechanics and the aircraft stability. The approach used is to vary the main geometric parameters such as the centre of gravity position and the aeroplane’s mass across the flight envelope, and to investigate the subsequent effect on the main spin characteristic parameters such as the angle of attack, pitch angle, sideslip angle, rotational rates, and recovery time. First of all, a literature review sums up the range of technical aspects that affect the problem of spinning. It reviews the experimental measurement techniques used, theoretical methods developed and flight test results obtained by previous researchers. The published results have been studied to extract the effect on spinning of aircraft geometry, control surface effectiveness, flight operational parameters and atmospheric effects. Consideration is also made of the influence on human performance of spinning, the current spin regulations and the available training material for pilots. A conventional-geometry, single-engine low-wing aeroplane, the basic trainer Fuji FA-200-160, has been instrumented with a proven digital flight measurement system and 27 spins have been systematically conducted inside and outside the certified flight envelope. The accuracy of the flight measurements is ensured through effective calibration, and the choice of sensors has varied through the study, with earlier sensors suffering from more drift than the current sensors (Belcastro, 2009 and Schrader, 2013). In-flight parameter data collected includes left and right wing α and β-angles, roll-pitch-yaw angles and corresponding rates, all control surface deflections, vertical speeds, altitude losses and the aeroplane’s accelerations in all three directions. Such data have been statistically analysed. The pitch behaviour has been mathematically modelled on the basis of the gathered flight test data. Nine observations have been proposed. These mainly cover the effects of centre of gravity and aircraft mass variations on spin characteristic behaviour. They have all been proven as true through the results of this thesis. The final observation concerns the generalisation of the Fuji results, to the spin behaviour of other aircraft in the same category. These observations can be used to improve flight test programmes, aircraft design processes, flight training materials and hence contribute strongly to better flight safety.
This chapter studies the algebra and calculus of vectors and matrices, as specifically applied to the USAF Test Pilot School curriculum. The course is a prerequisite for courses in Equations of Notion, Dynamics, Linear Control Systems, Flight Control Systems, and Inertial Navigation Systems. The course deals only with applied mathematics; therefore, the theoretical scope of the subject is limited.
