216 SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE VOL. 27 



In the construction of the equilibrium control wheel it was decided that 

 some arrangement must be secured whereby the wheel would normally be in- 

 active and maintain whatever position it had been set to, and at the same time 

 could he moved by the aviator with one hand, the mere act of grasping it ren- 

 dering it free to be moved, and whereby it must automatically lock itself in 

 any position in which it might be when the aviator removed his hand from it. 

 The multiplicity of things requiring the attention of the aviator made it desir- 

 able that his attention to any one of the important details, whether the engine, 

 the equilibrium, or the steering, should never require more than one hand, thus 

 leaving the other hand free either to hold on to the machine or to control some 

 other detail at the same time. "While an irreversible wheel, such as would be 

 secured by the use of a worm and worm-wheel, at first seemed likely to answer 

 the purpose, yet the movement of a worm-wheel by means of a worm is neces- 

 sarily very slow if it is irreversible, and it here seemed desirable to so arrange 

 the wheel that in case of emergency, or for rising or descending, the aviator 

 could swing the Penaud tail from its extreme upper position to its extreme 

 lower one by a small motion of his hand, and thus small or large adjustments 

 of the Penaud tail could be intuitively felt to have been produced without the 

 aviator having to remember how many turns be had made of the wheel. 



The control of the steering rudder was effected by a steering wheel (51) 

 similar in construction to the equilibrium control wheel (50), a continuous cord 

 (52) passing from the steering wheel through suitable pulleys to either side of 

 the steering rudder (r), springs being interposed in loops in the cord on either 

 side of the steering rudder to give some elasticity to the control apparatus in 

 order to prevent possible danger from the aviator attempting to move the rud- 

 der too suddenly. This steering rope passed directly through the steering rud- 

 der at the points where it was joined to it ; so that, should one side of the cord 

 in any way become entangled with the frame or with its pulleys, the strain pro- 

 duced by the aviator in attempting to move it in the opposite direction would 

 be taken up by the cord and thereby avoid the possibility of destroying the 

 rudder. For even should the cord become entangled on one side, the rudder 

 could be given a slight amount of adjustment through the elasticity of the 

 coiled springs. 



The design of the combined Penaud tail and rudder followed very closely 

 that which had been used for the models, and its area of ninety-five square feet 

 on the horizontal surface with a corresponding area of vertical surface bore 

 the same relation to the area of the tail and rudder of the models that the area 

 of the wings of the large machine bore to that of the wings of its prototype. 



While the provisions for automatic equilibrium and manual control were 

 not entirely ideal, even for the quiet atmospheric conditions under which it 





