CG1 CG2 represent the Center of Gravity as referred to the first, or horizontal, and to the second, or vertical plane, respectively.
CP represents the Center of Pressure[14] 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:
- “fw” refers to the front wings.
- “rw” refers to the rear wings.
- “r” refers to a state of rest.
- “m” refers to a state of motion.
- “1” refers to the plane XY.
- “2” refers to the plane XZ.
- “3” refers to the plane YZ.
“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 measurement. “Horse-power by formula” is given by Maxim’s formula:[15]
| HP = | rev. × diam. of propeller × pitch × thrust | . |
| 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 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. [p016]