142 SMITHSONIAH CONTRIBUTIONS TO KNOWLEDGE VOL. 27 



JULY 1 TO JULY 8 



The great disadvantage of conducting the experiments at a point forty 

 miles from the city and the shops was felt at all times. Workmen, even of the 

 very best class, cannot be kept contentedly at work at a point so far removed 

 from their homes, even by bringing them to the city on Saturday afternoon and 

 ranving them back to the experimental grounds the following Monday. More- 

 over, it is worse than useless to try to get even as much as one-third the ordi- 

 nary amount of work done if there is the slightest excuse for tightening anchor 

 ropes, watching passing boats, or wasting time on any of the multitudinous small 

 variations from their usual routine of life. 



On July 7, Aerodrome No. 5, equipped with " single-tier " wings and Pe- 

 naud tail, was made ready for a flight in the afternoon. The settings of the 

 wings, tail, etc., are given on Data Sheet 6. Using the " overhead " launching 

 apparatus, the aerodrome was launched with a steam pressure of 115 pounds. 

 Immediately upon being launched its bow rose to an angle of about fifteen de- 

 grees or more, and the aerodrome came backward and downward and touched 

 the water about three or four feet from the house-boat. 



It may be well to recall from what has been said in Part I, Chapter IX, that 

 Aerodrome No. 5 is the one with the very low thrust line, and in 1896 had its 

 " separator " several centimetres in front of its center of gravity. When this 

 aerodrome was overhauled just previous to these experiments, the separator 

 was moved back to the same relative position as that in Aerodrome No. 6, so that 

 the gradual depletion of the water supply during flight would not cause it to be- 

 come light in front of the center of gravity. 



In the launching of Aerodrome No. 5, above described, it showed no ten- 

 dency to drop immediately upon leaving the launching ways, but on the con- 

 trary its bow in every case rose almost immediately until it was at an angle of 

 aboul fifteen degrees or more. From the photograph (Plate 35) it will be no- 

 fciced that the wings of the aerodrome are held down by the longitudinal strips, 

 A, fastened to cross beams attached to the launching car. If, now, the launch 

 ing speed is too great and the aerodrome tries to rise immediately upon being 

 released, the front end, which passes from under the launching car before the 

 rcai' does, and is thus free to rise, will immediately rise, while the rear cannot 

 rise until it has passed entirely in front of the car, which being a distance of 

 several feet requires an appreciable fraction of a second, during which time the 

 bow of the machine has been able to rise to quite a steep angle. This has the 

 effect of slowing down the aerodrome so that it does not get quite the proper 

 chance to start on its flight with a minimum head resistance. 



In view of the above facts, it, was decided to decrease the speed of the 

 launching car slightly when using Aerodrome No. 5, so that this matter could 

 be thoroughly tested out. 



