150 SMITHSONIAN CONTRIBUTIONS TO KNOWL.EDG1 Vol.. Li 



probable thai the failure of the flight was due to lack of power. The data on 

 settings of wings, tail, etc., are given on Data Sheet No. 11. 



The speed of the launching car, one foot in front of the point at which 

 the aerodrome was released, was twenty feet a second, as shown by the carbon 

 record sheet carried by the launching car and moved in front of a tuning fork 

 which had been set in vibration. 



The aerodrome, being uninjured in the previous flight, was again placed on 

 the " underneath " launching apparatus, and before attaching the wings a short 

 run was made in order to see that everything was in proper working condition. 

 As everything seemed to be all right, the wings and tail were immediately ad- 

 justed for another trial. As the bow was slightly elevated in the previous trial, 

 it was thought best to bring the CG a little farther forward, and this was ac- 

 cordingly done. As the aerodrome also seemed to drop slightly in leaving the 

 launching car in the above trial, the tension of the launching springs was slightly 

 increased so as to increase the velocity at the moment of release. 



.lust as the sun was setting the aerodrome was again launched, 1 minute and 

 30 seconds having been required to raise 120 pounds steam pressure, but the 

 pressure was rising very rapidly at the moment of launching. There was an 

 absolutely dead calm prevailing, the river being as smooth as glass. The launch- 

 ing apparatus, with the disappearing track, worked perfectly. Immediately 

 upon being released the aerodrome went straight ahead, with its midrod hori- 

 zontal, but gradually glided downward as though the wings had very little lift- 

 ing power, and settled in the water about 200 feet from the house-boat. The ve- 

 locity of the launching car, 1 foot before the aerodrome was released, was 22 

 feet a second, as shown by the carbon record sheet. 



In the above trials of the superposed wings, the conditions of the wind and 

 of the aerodrome were certainly as favorable as could be expected. There was 

 as much power being furnished by the engine as had been furnished in the pre- 

 vious flights with the " single-tier " wings, and the balancing of the aerodrome 

 was exceedingly good. The superposed wings, unquestionably, bad a fair trial 

 an. I proved inferior to the " single-tier " ones, for they had a supporting sur- 

 face of 2.7.") square feet to the pound, whereas with the " single-tier" wings 

 there was approximately 2 square feet to the pound. The decreased lifting 

 power of the superposed wings seems to be another confirmation of the results 

 of the Allegheny experiments with the " plane-dropper." 2 



A- more time had already been given to these tests than it seemed well to 



See " Experiments in Aerodynamics." It will be recalled that in the experiments with the 

 "plane-dropper" there was a greatly reduced lifting power with superposed planes when their dis- 

 . aparl was oni half the width of the planes, unless a speed of alioiit 42.5 feet a second was ob- 

 ied. In the above tests with the superposed wings, the speed «:is only from twenty to twenty- 

 two feel a second at the time of launching, ami as the distance between the surfaces was only one- 

 ti.il i as their width, it is not surprising that the lifting power should not be as great as with 



the " single-tier " wings. 



