Analytical Criterion for Aircraft Spin Susceptibility

摘要

AIRCRAFT spin ismysterious, exciting, dangerous, and perhapsnthe biggest unsolved problem in flight mechanics. Spin is ancritical phenomenon for bothmilitary and general aviation airplanes,nand hence a matter of concern to aircraft designers and flight testnengineers. Abzug and Larrabee [1] provide an instructive account ofnthe history of spin research. Traditionally, spin onset was viewed asnan instability problem along the lines of wing rock, yaw departure,nnose slice and others of that ilk, leading to criteria for spin suscep-ntibility of aircraft configurations, such as the widely usedWeissmanncriterion [2]. Also of interest was the prediction of equilibrium spinncharacteristics (yaw rate r, angle of attack u0001, etc.) and identifyingncontrol combinations favoring entry into spin and recovery fromnspin, typically using approximate methods and reduced-ordernmodels [3,4]. However, with the introduction of bifurcation methodsnand the use of continuation algorithms, it became possible to worknwith the complete set of aircraft equations of motion with nonapproximation, and to numerically compute all steady states andnidentify all points of instability onset [5,6]. It became clear that spinnwas primarily a high-u0001 steady state with large angular rates whichncould itself be either stable or unstable. Entry into spin was typicallynfound to occur by way of a jump phenomenon due to onset of anninstability on a coexisting low-u0001 branch of steady states [7]. Thennature of the spin (steady or oscillatory, erect or inverted, flat or steep,nleft- or right-hand) could be predicted froma bifurcation analysis andnstrategies to recover from spin could be worked out [8].