 piston theori - aerodynam tool aeroelastician piston theori - aerodynam tool aeroelastician repres applic describ illustr extent simplif solut high-speed unsteadi aeroelast problem achiev aerodynam techniqu collect piston theori base physic model origin propos hay lighthil piston theori airfoil finit wing systemat develop landahl util expans power thick ratio invers flight mach number contribut order neglig theori predict point-function relationship local pressur surfac wing normal compon fluid veloc produc wing's motion comput gener forc aeroelast equat flutter determin reduc elementari integr assum mode motion essenti close-form solut bend- torsion control-surfac flutter properti typic airfoil high mach number agre well exact theori comparison fairli demonstr increasingli influenc thick profil shape grow larger discoveri imposs aerodynam tool complex practic flutter analys-e three-dimension wing panel-is reduc piston theori iter procedur outlin improv flutter eigenvalu success introduct higher-order term applic unsteadi superson problem review includ gust respons rapid maneuv elast aircraft steadi-state aeroelast calcul discuss piston theori amount slight modif ackeret's formula suggest futur base aerodynam method emphasi area comput labor reduc minimum loss precis point mach number zone exist thermal effect appreci nonlinear viscou interact neglect zone piston theori logic estim air load analyz aerodynam- thermoelast interact problem 