98 SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE VOL. 27 



time, painstaking and cost to the hazard of destruction. Willi the experience 

 jnsl acquired from the trial of No. 4, the whig of No. 5 was set at an angle of 

 about 20 with the midrod, and the tip was secured by a light cross-piece, so 

 guyed that the wing as a whole, while set at this considerably greater angle with 

 the rod, was stiffer than before. In addition to this, the air chamber was moved 

 hack so thai the center of gravity was from 6 to 10 cm. behind the (calculated) 

 enter of pressure. These changes were made in order to insure that the front 

 should al any rate keep up, and it did. 



The aerodrome was launched successfully with the engines working under 

 a pressure of 110 pounds of steam. The head rose continually until the mid- 

 rod stood up at an anide of about 60°, checking all further advance. It re- 

 mained in the air in a stationary position for nearly a second, and then slid back- 

 ward into the wafer, striking on the end of the rudder and bending it. The dis- 

 tance flown was about 12 metres, and the time of flight 3 seconds. One of the 

 propellers was hroken short off, and the shaft was bent- 

 It thus became clearly evident that some cause prevented the proper balan- 

 cing of the machine, which was necessary to secure even approximately the the- 

 oretically simple condition of horizontal flight. It was all-important that the 

 angle of the front wing should be correct, but its position could not be accurately 

 known in advance of experiment, and this experiment could only be made with 

 the machine itself, and involved the risk of wrecking it. 



These trials gave a very vivid object lesson of what had already been antici- 

 pated," that the difficulties of actual flight would probably lie even more in ob- 

 taining exact balance than in the first and more obvious difficulty of obtaining 

 the mere engine power to sustain a machine in the air. The immediate problem 

 was to account for the totally different behavior of the two aerodromes in the 

 two flights, under not very different conditions. 



Observations of the movement of the two aerodromes through the air, as 

 seen bj the writer from the shore, seemed to show, however, that the wings 

 did not remain in their original form, but that at the moment of launching there 

 was a sudden flexure and distortion due to the upward pressure of the air. The 

 time of flight was too short, and the speed too great, to be sure of just what did 

 occur, bul if seemed probable that the wings flexed under the initial pressure of 

 the weight which came upon them at the moment of launching, and that they 

 were in fact, while in the air, a wholly different thing from what they were an 

 instant before, so that a very slight initial difference in the ans-le at which they 

 first met the air might cause the air to strike in the one case on the top of the 

 wings and throw the head down, and in the other case so as to throw the head up. 

 To ascertain the extent and character of this flexure, caused, il will be observed, by 



•"Experiments in Aerodynamics." 



