STORY OF EXPERIMENTS IN MECHANICAL PLIGHT. 181 



Aerodrome No. 5 (1896). 



Dr. Langley has two successful aerodromes, IS'o. 5 and No. 6; the 

 former made the flights of May 6 and the latter that of November 28. 

 The Plate gives scale drawings of No. 5. The weight of this, with fuel 

 and water sufficient for the flights described, is about 30 pounds. The 

 weight of the engine and boiler together is about 7 pounds. The power 

 of the engine under full steam is rather more than 1 horsepower. 

 There are two cylinders, each having a diameter of IJ inches. The 

 piston stroke is 2 inches. The two screws are 39 inches from tij) to tip, 

 and are made to revolve in opposite directions; the pitch is 1^; they 

 are connected to the engines by bevel gears most carefully made; the 

 shafts and gears are so arranged that the synchronous movement of 

 the two screws is secured. The boiler is a coil of copper tubing; the 

 diameter of the coil externally is 3 inches; the diameter of the tubing 

 externally is three-eighths of an inch; the pressure of steam when the 

 aerdrome is in flight varies from 110 to 150 pounds to the square inch. 

 The flame is produced by the selopile, which is a modification of the 

 naphtha "blow torch" used by plumbers; the heat of this flame is 

 about 2,000° F. Four pounds of water are carried at starting, and 

 about 10 ounces of naphtha. In action the boiler evaporates about 1 

 pound of water per minute. Flights could be greatly lengthened by 

 adding a condenser and using the water over and over again, but, as 

 Dr. Langley says, the time for that will come later. 



