RIGID STABLE AEROPLANES. 



381 



RIGID STABLE AEROPLANES. 

 By L. Hargrave. 



[With Four Drawings.] 



[Read before the Royal Society of N. S. Wales, December 1, 1909.'] 



The rapid progress of aeronautics is hampered and delayed 

 by the want of a method of ensuring automatic longitudinal 

 and transversa] stability. To remove this obstacle I repeat 

 or refer to such knowledge as has come under my notice, 

 my own previously expressed views, and also describe and 

 exhibit my last experiments and explain their novelty and 

 utility. 



We find that Dr. Thomas Young 1 proved in 1800, that a 

 certain curved surface suspended by a thread approached 

 an impinging air current, instead of receding from it. This 

 surface was a reverse curve like Fig. 16, Plate xvn, this 

 Journal, Vol. xxxi, 1897. 



This curve has been worried over and tried by many kite 

 and flying machine men with no appreciable success, or it 

 would be used in all the flyers of to-day. Then there are 

 my papers, " On the Cellular Kite, 2 and on "Aeronautics." 3 

 Then we have the all important article by W. R. Turnbull, 

 on "Form and Stability of Aeroplanes." 4 



A careful reading of the articles and matter referred to 

 will make it clear that the road was paved with velvet 

 and I had only to dance along it and make 



(1) One section of a multiple planed flying machine with 

 reverse curves and which possessed automatic stability. 



1 Progress in Flying Machines, by O. Chanute, p. 9. 



2 This Journal, Aug. 5, 1896, p. 144. 3 hoc. cit., June 1, 1898, p. 55. 

 4 Scientific American Supplement, No. 1726, Jan. 30, 1909. 



