NO. 3 LAN(;LK1 MKMOII! ON MECHANICAL FLIGHT L5 



Lastly, when measurements arc made on or parallel to the line )', the point 

 Owill be marked 3500 centimetres, and distances toward the East will be greater 

 than, and distance's toward the West will be less than 3500 centimetres. Meas- 

 urements in these latter directions will be comparative!} infrequenl because the 

 center of gravity arid center of pressure both lie in the plane XZ. 



EXAMPLE 



Iii the figure the point T in the tail, if 15 centimetres to the South of 0, 

 would be graduated 1485 centimetres. A weight (W) 25 centimetres below the 

 axis, would be graduated 2475 centimetres. A point 50 centimetres above the 

 axis would be graduated 2550 centimetres, etc. 



('(! represents the Center of Gravity of the aerodrome, or (with subscript 

 letters) of any specially designated part, or with reference to some indicated 

 condition. 



CGi CG 2 represent the Center of Gravity as referred to the first, or hori- 

 zontal, and to the second, or vertical plane, respectively. 



CP represents the Center of Pressure 7 of the whole aerodrome, or (with a 

 subscript) of any specially designated part. 



CF represents the Center of Figure of the aerodrome, or of any specially 

 designated part. 



Subscripts : 



"fiv" refers to the front wings. " 1 " refers to the plane XY. 



">«'" refers to the rear wings. " 2 " refers to the plane XZ. 



11 r " refers to a state of rest. " 3 " refers to the plane YZ. 



11 m " refers to a state of motion. 



"A" represents the total area of the supporting surface; " a " represents the 

 total area of the tail; HP represents the horse-power by Prony brake measure- 

 ment. " Horse-power by formula " is given by Maxim's formula: 8 



rev. xdiam. of pro peller x pitch ■ thrust 

 Hp — 33,000 



(This formula was not in use at the time of the rubber-motor experiments, for 

 which the thrust was not taken. It appears to assume that the conditions where 

 the screws from a fixed position move a mass of still air, are the same as those 

 of free flight. Its results, however, are in better agreement with experiment 

 than might be anticipated.) 



" Flying-weight " means everything borne in actual flight, including fuel 

 and water. 



'The aerodrome is sustained by the upward pressure of the air. which must be replaceable by 

 the resultant pressure at some particular point, designated by CP. 



"Si f'entury Magazine. October, 1S91. 



