NO. 3 LANGLEY MEMOIR ON MECHANICAL FLIGHT 107 



hour from (lie northeast. At 1.10 p. m. Aerodrome No. G was launched, but the 

 guy-wire uniting the wings having apparently caughl on one of the fixed wooden 

 strips which held the wings down, the left wing was broken before the aero 

 drome was really launched, and the result was that the machine slowly settled 

 down in the water by the boat, breaking the propellers and slightly injuring 

 the Penaud tail. 



After removing No. G from the water, No. 5 was placed on the launching 

 car and immediately prepared for a test. At 3.05 p. m. it was launched at a 

 steam pressure of 150 jiounds and started directly ahead into the gentle breeze 

 which was then blowing. The height of the launching track above the water 

 was about twenty feet. Immediately after leaving the launching track, the aero- 

 drome slowly descended three or four feet, but immediately began to rise, its 

 midrod pointing upward at. an increasing angle until it made about ten degrees 

 with the horizon and then remained remarkably constant at this angle through 

 the flight. Shortly after leaving the launching track the aerodrome began to 

 circle to the right and moved around with great steadiness, traversing a spiral 

 path, as shown in the diagram (Plate 19). From an inspection of the diagram, 

 it will be noticed that the aerodrome made two complete turns and started on the 

 third one. During the first two turns the machine was constantly and steadily 

 ascending, and at the end of the second turn it bad reached a height variously 

 estimated by the different observers at from 70 to 100 feet. When at this height, 

 and after the lapse of one minute and twenty seconds, the propellers were seen 

 to be moving perceptibly slow T er and the machine began to descend slowly, at 

 the same time moving forward and changing the angle of inclination of the 

 midrod until the bow pointed slightly downward. It finally touched the water 

 to the south of the house-boat at the position shown, the time the machine was 

 in the air having been one minute and thirty seconds from the moment of launch- 

 ing. The distance actually traversed, as estimated by plotting its curved path 

 on the coast-survey chart and then measuring this path, was approximately 3300 

 feet, which is the mean of three independent estimates. This estimate of the 

 distance was checked by noting the number of revolutions of the propellers as 

 recorded by the revolution counter, which was set in motion at the momenl the 

 machine was launched. On the assumption that the slip of the propellers was 

 not greater than fifty per cent, the 11G6 revolutions as shown by the counter 

 would indicate a distance travelled of ^4.'!i> feet. As it was felt very certain 

 that the slip of the propellers could not have amounted to as much as fifty per 

 cent, it seemed a conservative estimate to place the length of flight at 3000 feet, 

 which would mean a rate of travel of between '20 and 25 miles an hour. The cir- 

 cular path traversed by the aerodrome was accounted for by the fact that the 

 guy-wires on one of the wings had not been tightened up properly, thus causing 

 a difference in the lifting effect of the two sides. 



