

214 SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE VOL. 27 



endless cord (20) which after passing over suitable pulleys was connected to the 

 control wheel (51) at the aviator's car. 



A model of this device was constructed in the spring of 1900 and was tested 

 with steam pressure in the shop. The test showed that the device acted imme- 

 diately and with precision, the piston performing movements simultaneously and 

 in exact accordance with the pendulum. The device, however, was never tried 

 in a flight of any of the aerodromes owing to the lack of time necessary to prop- 

 erly install it on the machine. Furthermore, it was thought probable that the 

 rapid acceleration of the aerodrome at the moment of launching would so dis- 

 turb the pendulum as to cause it to be in a very different position from that 

 of vertical, and also that the motion of the aerodrome through the air would 

 itself be a somewhat disturbing factor. 



Because of the difficulties involved in this or any other mechanical device 

 for controlling the equilibrium, it was in every way advisable to retain in the 

 large machine the Penaud system, which, though itself imperfect in many ways, 

 had been thoroughly tested in actual flight. In the models, it will be remem- 

 bered, the combined Penaud tail and rudder controlled the longitudinal equilib- 

 rium by movement in the vertical plane under the combined influence of its ini- 

 tial negative angle and the elasticity of its connection with the frame, the flight 

 being kept as nearly as possible in a straight line by the vertical surfaces of 

 the tail. Although it was necessary that the large aerodrome should be 

 capable of being steered in a horizontal direction, it was felt to be unwise to 

 give the combined Penaud tail and rudder motion in the horizontal plane in 

 order to attain this end, since the use of it for such a double function might 

 very seriously interfere with its proper action in preserving the longitudinal 

 stability. It was, therefore, at first thought best to dissociate the rudder and 

 tail so that the rudder might be used for horizontal steering without in any 

 way interfering with the proper functioning of the tail. But, as the main de- 

 sideratum was to obtain a flight of the large machine as soon as possible, and 

 perfection of steering control seemed secondary, it was decided, after further 

 consideration, in order not to risk the unpredictable effects that might result 

 from small changes, to duplicate on the large machine the combined Penaud 

 tail and rudder of the model, and to add another rudder for steering in the 

 horizontal plane. Constructional requirements determined as the only avail- 

 able position for this rudder a rather disadvantageous one. As will be seen 

 from Plate 53, its efficiency was diminished by its being only about half as far 

 from the center of gravity as (lie combined Penaud tail and rudder, and by 

 being located in the lee of a considerable portion of the frame, where it would 

 be subject to the cross-currents of air created by the forward motion of the 

 frame. 



