NO. 3 



LANGLEY MEMOIR ON MECHANICAL FLIGHT 



(;:; 



such a point that a pressure of from 70 to 80 pounds of steam could be main 

 tained for 70 seconds, when it was tested in the shop. What it would do under 

 the unfavorable conditions imposed by flight was to be learned only by trial. 



At this pressure, the engines, the efficiency of which had been increased by 

 an improvement in packing, would develop approximately 0.4 indicated H. P., 

 while at 105 pounds pressure they at times developed as much as 0.8 II. P. 

 When the aerodrome was tested on the pendulum, these engines, when making 

 less than 700 revolutions per minute, lifted over 40 per cent of the total flying 

 weight. 



The propellers used at this time were accurate helices, having a diameter of 

 60 cm., a width of blade of approximately 36 degrees, and a pitch-ratio of 1.25. 

 They were formed of wood, and were bushed with brass where they were at j 

 tached to the shafts. 



AERODROME OLD NO. 4 AS PREPARED FOR FLIGHT BEFORE BEING SHIPPED FOR TRIAL 



ON NOVEMBER 14, 1S93 



Permanent air spaces: 



in midrod, vol. = 355 ec, 



in engine frame, vol. = 100 cc 



volume as per II. 2050 cc 



1 



2505 cc. 



4 1 32 1 



Deusity= ^EoB =1.65 I m. 



