Nc. 3 LANGLEY MEMOIK ON MECHANICAL FLIGHT 105 



and it was impossible to make the launching apparatus poinl directly into the 

 wind, which was blowing from the rear of the boat. An attempt was made to 

 launch the aerodrome even with the wind blowing at its rear, but it was found 

 impossible to make the fires burn and the test was accordingly postponed. Later 

 in the afternoon the house-boat was floated and the preparations for a test were 

 immediately completed. At 5.4l' p. m. the fires were lighted, but the burners did 

 not work properly and the proper steam pressure could not be obtained. At 

 6.20 p. m. the fires were again lighted, and at 6.22 the aerodrome was launched, 

 its midrod having an upward angle of 25 degrees, or more, with the launching 

 track. The aerodrome moved off nearly horizontally, but seemed to be very 

 sluggish in its movement and fell in the water about seventy feet from the boat, 

 after having been in the air only 4.8 seconds. The damage consisted of a broken 

 propeller and a slight strain in the main frame, the extent of which, however, 

 was not immediately seen. 



The steam pressure at the time of launching was 110 pounds, which was ob- 

 viously insufficient. The aerodrome had lifted fifty per cent of its weight on the 

 pendulum, and its sluggishness of movement seemed, therefore, unaccountable 

 even for this pressure. It seemed probable, however, that the pressure ran down 

 immediately after the machine was launched, on account either of the use of 

 the light-weight burners in place of the larger and heavier ones, or of the dim- 

 inution of the air pressure in the gas tank. 



At 7.55 the aerodrome was again launched, and this time made a still shorter 

 flight than before, being in the air only three seconds. A serious leak in the en- 

 gine cylinder was, however, discovered just as the machine was launched, and 

 this probably accounted for the lack of power. 



Not only had the tests which have just been described indicated that there 

 was a lack of power during flight, although previous pendulum tests had repeat- 

 edly shown lifts greater than fifty per cent, but, furthermore, the wings them- 

 selves, while appearing perfectly capable of supporting the aerodrome when 

 viewed with the machine stationary, were seen to flex to such an extent in flight 

 that it seemed probable that much of the power was consumed in merely over- 

 coming the head resistance of a large portion of the wings which had lost all 

 lifting effect. 



During the fall and winter, as recorded in Chapters VII and VI [f, Aero- 

 drome " New No. 4," which had been reconstructed during the summer, and 

 which upon test was found radically weak, was almost entirely rebuilt and after- 

 wards known as No. 6. Important changes were also made in No. 5, which 

 greatly increased its strength and power. The improvements, however, which 

 contributed more than anything else to the marked success achieved in the next 

 trial of the aerodromes, were those which had to do with the nature and dispo- 

 sition of the sustaining surfaces and the means for securing equilibrium. 



