1bo^oInus JFun^ 



PART I. LONGITUDINAL MOTION 

 §1. INTRODUCTION AND CONCLUSIONS 



The present dynamical investigation of the stabiHty of motion of 

 aeroplanes is based upon the well-known theory of small oscillations 

 of rigid dynamics as first applied by Bryan ^ to aeroplanes and ex- 

 tended by Bairstow.' The necessary coefificients for use in the equa- 

 tions of motion were determined by model tests in the wind tunnel of 

 the Massachusetts Institute of Technology. 



The application of model experiments to predict the performance 

 of full-size aeroplanes is now so well established that no general 

 discussion of the theory of models is undertaken. A great part of 

 the actual experimental work was performed by Messrs. Hufif and 

 Douglas. The oscillating apparatus was designed by Mr. Chow 

 under the direction of Professor E. B. Wilson of the Department of 

 Mathematics. Captain A. E. Clark, \J. S. A., while a student in 

 aeronautical engineering, designed an aeroplane which was selected 

 as one type for investigation. 



It is necessary to acknowledge the cordial interest taken in the 

 work by Professor C. H. Peabody, head of the Department of Naval 

 Architecture. From the beginning of aeronautical research in his 

 department, Professor Peabody has offered the warmest encourage- 

 ment by countless arrangements to facilitate progress and to pre- 

 vent interruptions. 



Following the analysis of Clark's aeroplane, the work was repeated 

 for a model of a military aeroplane known as Curtiss JN2.' The 



' G. H. Bryan, " Stability in Aviation." 



" Technical Report of the Advisory Committee for Aeronautics, London, 

 1912-13. 



^ Plans and description given in " First Annual Report of the National Ad- 

 visory Committee for Aeronautics" (Report No. i, "Report on Behavior of 

 Aeroplanes in Gusts," by J. C. Hunsaker and E. B. Wilson, Washington, D. C, 

 1916). Senate Document No. 268, 64th Cong., ist Sess. 



Smithsonian Miscellaneous Collections, Vol. 62, No. 5 



