SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO3 



23 



necessary that the large aero- 

 drome should be capable of being 

 steered in a horizontal direction, 

 it was felt to be unwise to give 

 the Penaud tail and rudder mo- 

 tion in the horizontal plane in 

 order to attain this end". (L.M. 

 p. 214). 



Keel : A fixed vertical surface 

 underneath the main frame mea- 

 suring 3'2" in height by 6' aver- 

 age length. Area 19 sq. ft. (L.M. 

 pl. 53). 



Curtiss control post directly in front 

 of the pilot. 



Keel : Entirely omitted. 



SYSTEM OF CONTROL. 



24 Lateral Stability : The dihedral 

 only was used for maintaining 

 lateral balance. (L.M. p. 45). 



26 



Longitudinal Stability : Lang- 

 ley relied upon the Penaud system 

 of inherent stability for maintain- 

 ing the longitudinal equilibrium. 

 "For the preservation of the equi- 

 librium [longitudinal] of the aero- 

 drome, though the aviator might 

 assist by such slight movements 

 as he was able to make in the 

 limited space of the aviator's car, 

 the main reliance was upon the 

 Penaud tail." (L.AI. p. 215). 



Steering : Steering in the hori- 

 zontal plane was done entirely by 

 the split-vane steering rudder lo- 

 cated underneath the main frame. 

 (L.M. p. 214). 



Lateral Stability : Three means 

 were used for securing lateral balance 

 at Hammondsport : The dihedral 

 angle as used by Langley, a rudder 

 which "serves as a vertical aileron" 

 (Zahm affidavit p. 6), and the Penaud 

 tail rudder. The last two constituted 

 a system "identical in principle with 

 that of Complainant's [Wright] com- 

 bined warping of the wings and the 

 use of the vertical rudder". (Zahm 

 affidavit p. 6). 



Longitudinal Stability: At Ham- 

 mondsport the Penaud inherent longi- 

 tudinal stability was supplemented 

 with an elevator svstem of control. 



Steering: On one day, May 28, 1914, 

 steering in the horizontal plane was 

 done with the vertical rudder which 

 had been substituted for the original 

 Langley split-vane steering rudder. 

 After May 28th the steering was done 

 by the vertical surface of the tail rud- 

 der (Zahm affidavit p. 7), which in 

 1903 was immovable about a vertical 

 axis, (L.M. p. 214). 



