NO. 3 LANGLEY MBMOIB ON MECHANICAL PLIGHT 117 



These weights are those determined in December, 1896, when some slighl 

 changes had been made from the conditions existing al the time of the flighl by 

 this aerodrome on May 6. Previous to that time, with a pressure of 130 pounds, 

 between 1.1 and 1.25 horse-power was given on (lie Prony brake. Al the actual 

 time of flight the pressure was about 115 pounds, and the actual power very 

 nearly 1 horse-power. 



The valve stein was pivoted to the center of the valve partly because this was 

 the lightest connection that could be made, and partly to allow the valve per- 

 fect freedom of adjustment upon the seat. Many parts, such as guides, braces, 

 crank-pins, wrist-pin and shafts, are hollow. The steam is taken in at the front 

 end of the steam chest, and the exhaust taken out of the center, whence it is led 

 back to the stack and by. means of a forked exhaust pipe discharged in such a 

 way as to assist the draught of each coil of the boilers. Like the cylinder the 

 steam chest is made of a piece of steel tubing, 20mm. diameter on the outside, 

 with an inside diameter of 19 mm., and is fitted with a cast-iron bushing 0.5 mm. 

 thick, making the inside diameter of the steam chest 18 mm. It, too, has flanges 

 brazed to the ends, to which the heads are held by small machine screws. 



The shaft for conveying the power to the propeller shafts extends across 

 the machine from side to side; it is hollow, being 8mm. outside diameter, with 

 a hole 5 mm. diameter through the center. 



It is formed of five sections : the middle section, containing the crank, has 

 a length of 110 mm. and is connected at either end, by flanged couplings, to 

 lengths 320 mm. long, which are in turn extended by the end sections having a 

 length of 230 mm. In addition to the four main bearings that are bolted to the 

 prcssed-steel bed-plate already mentioned, there are two bearings on the outer 

 framework on each side. At the outer end of each shaft there is keyed thereto 

 a bevel gear with an outside diameter of 27 mm. and having 28 teeth. This gear 

 meshes with one of 35 teeth upon a shaft at right angles to the main shaft and 

 parallel to the axis of the aerodrome. These two shafts, one on either arm, 

 serve to carry and transmit the power to the propellers. They are 192 mm. long, 

 8 mm. in diameter, and are provided with three bearings that are brazed to a 

 corrugated steel plate forming the end of the outrigger portion of the frame. 

 These shafts are also hollow, having an axial hole 4 mm. in diameter drilled 

 through them. The propeller seat has a length of 43 mm. and the propeller is 

 held in position by a collar 25 mm. in diameter at the front end, from which 

 there project two dowel-pins that fit into corresponding holes in the hubs of the 

 propellers, which are held up against the collar by a smaller one screwed into 

 the back end of the shaft. The thrust of the collar is taken up by a pin screwed 

 into the end of the forward box and acting as a step against winch the shaft 

 bears, the arrangement being clearly shown by the accompanying drawing, 

 Plate 26A. 



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