CHAPTER XI 

 SHOP TESTS OF THE AEBODROME 



In June, 1902, after the proper adjustments of the carburetor and other 

 accessories of the engine had been accurately determined in the tests on the test 

 ing frame, the engine was assembled in its proper position in the aerodrome 

 frame and connected to the propellers. The aerodrome frame was then mountei I 

 directly on the floor of the launching car, which was placed on a short track- 

 laid on the floor of the shop, as previously described. A large spring balance, 

 which had been previously calibrated, was then connected between the car and 

 an upright fastened to the track, and tests were made to determine the thrust 

 developed when the engine drove the propellers at different speeds. Upon find- 

 ing that there was comparatively little vibration when the engine was driving 

 the propellers even at its maximum speed, it was felt safe to raise the aero- 

 drome from the floor of the car and place it upon the uprights on which it would 

 be supported in launching it. Quite an extended series of tests was then 

 made, and although the uprights raised the aerodrome frame until the mid rod 

 was practically 9 feet from the floor of the car, and in the tests at maximum 

 power the propellers developed an average thrust of 450 pounds, yet it was 

 found that the clutch hook held the bearing points of the frame so securely on 

 the uprights of the car that all fear that the aerodrome might break loose from 

 the car during the launching process was removed. 



Upon the completion of these tests, which had proved most satisfactory, 

 the aerodrome frame was supported from the ceiling of the shop by means of 

 four short coil springs which reproduced as nearly as possible the elastic or 

 flexible suspension which the aerodrome would have when supported by its 

 wings in the air. These springs were attached at the same points on the 

 main frame of the aerodrome at which the wings would be attached, thus per- 

 mitting a careful study of the amount of flexure and vibration which it would 

 undergo in actual flight. The most remarkable difference in the nature of the 

 vibration induced in the frame was found when the aerodrome was thus 

 supported by springs. When it was supported on the rather unyielding launch 

 ing car, the general tremor set up in the frame by the engine and propellers 

 was, while small, yet harsh, the effect on a person standing in the aviator's car 

 being rather unpleasant in the joints of the knees when experienced for several 

 minutes. When the frame was suspended by the springs it was found that all 

 this harshness of tremor disappeared, it being replaced by a slight general and 

 rapid tremor of the whole frame, which was not at all unpleasant, and which 



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