The evolution of fixed wing aircraft handling qualities during the first fifty years

Abstract

The study investigates the evolution of the handling qualities of British aircraft between 1910 and 1950. In this era, before the implementation of rigorous airworthiness requirements, many aircraft were deficient in some form or another by modern standards. Such deficiencies may not be anticipated or understood by today’s pilots who wish to fly old aircraft and this can result in mishandling, loss of control and ultimately accidents. This study uses a combination of quantitative analysis and qualitative judgements from historical sources to investigate vintage aircraft flying qualities. It includes analysis which makes a novel contribution to this area of aeronautics. Contemporaneous pilot accounts reveal that the understanding of the ‘mechanics of flight’ was generally poor. Legacy flight instructor handbooks show that early flying ‘folklore’ tends to outlive its usefulness and also reveal deficiencies in stability and control in the contemporary training aircraft. An analysis was conducted using a group of 41 aircraft, which formed a representative example of British aircraft of the era. The longitudinal, directional and lateral, stability and control parameters were estimated using generic equations and known aircraft geometry. Today’s certification specifications are used as a benchmark against which the vintage aircraft1 in this study are assessed for non-compliances. This analysis shows an inverse near-linear relationship between the year of design of an aircraft and the number of deficiencies it exhibits. Other factors that can affect handling qualities including the cockpit interface, and the aircraft environment are discussed. An analysis of these factors is made to highlight the higher risk areas when flying the vintage aircraft of the era. 1 In this thesis the expression ‘vintage aircraft’ refers to aircraft which were originally designed during the period 1900-1950. The findings are used to develop guidance for a modern pilot2 , planning to fly a strange vintage aircraft for the first time. 2 For the purposes of this study a ‘modern pilot’ is one who has been trained using aircraft certificated to modern certification standards or their military equivalent.