NO. 3 LANGLEY MEMOIB ON MECHANICAL FLIGHT 109 



rately on this account. The balancing of Aerodrome No. 6 had been made the 

 same as that of No. 5, but in No. (J the Hue of thrust was twelve centimetres 

 higher, and this fact, which had not been taken into account in determining the 

 proper balancing for No. 6, seemed to be sufficient cause for the aerodrome 

 coming down into the water so soon after being launched. Darkness had de- 

 scended before the aerodrome could be recovered and prepared for a second 

 trial. On the next day, November 28, a high wind prevailed in the morning, 

 but in the afternoon it became comparatively calm, and No. 6 was launched at 

 4. IK) p. m. under the same conditions as on the preceding day, except that the 

 float, which weighed 275 grammes, was moved back from the bowsprit eighty 

 centimetres in order to make the machine lighter in front. The aerodrome was 

 launched at a steam pressure of not much over 100 pounds, the air draft for 

 the burners being temporarily bad. The midrod made an angle of approximately 

 three degrees with the horizontal. On account of a slight rain, which had oc- 

 curred just before the machine was launched, the wings were wet and the weight 

 of the entire aerodrome was doubtless as much as twelve kilos. Immediately on 

 being launched the aerodrome started directly ahead in a gentle south wind, 

 moving horizontally and slowly turning to the right and appearing to approach 

 dangerously near to some' thick woods on the west shore. However, it fortu- 

 nately continued turning until it pointed directly up the beach with the wind 

 in the rear. It then moved more rapidly forward, dipped and rose but once, 

 and this very slightly, and continued its remarkable horizontal flight, varying 

 not more than two yards out of a horizontal course, and this only for a mo- 

 ment, until it finally descended into the bay at a point nearly in a line between 

 the house-boat and the railroad station at Quantico. Upon being recovered, it 

 was found to be absolutely uninjured, and another flight would have been made 

 with it immediately but darkness had descended. The time of flight, as deter- 

 mined independently by two stop-watches, was one minute and forty-five sec- 

 onds. The number of revolutions of the propellers was 2801, or at the rate of 

 1(500 R. P. M., which, with an allowance of fifty per cent slip, should have car- 

 ried the aerodrome a distance of 4600 feet in one and three-quarter minutes. 

 While the distance from the house-boat in a straight line to the point at which 

 the aerodrome descended was only about 1600 feet, yet it was estimated by those 

 present that this straight-line distance was certainly not greater than one-third 

 the total length of the path traversed, which would mean a distance of something 

 like 4800 feet. The length of the course, as plotted on the coast-survey map 

 and afterwards measured, was 4200 feet, and it, therefore, seemed safe to say 

 that the total distance travelled was about three-quarters of a mile, and the 

 speed was, therefore, about thirty miles an hour. 



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