ORIGINAL: Antique
Look at the attachment and So if the experts say their plane with a 6 pitch prop goes over 100 mph @ less than 10 or 12,000 rpm
are Rossi engineers wrong ??
Dear Antique,
I believe your are referring to this statement below from the file produced by ROSSI,
"The maximum possible speed (in miles per hour) of a propeller-driven airplane equals the
propeller pitch in inches times the propeller RPM in thousands.
12 - 6 prop @ 12,000 rpm : 6 X 12 = 72 mph maximum possible speed
12 - 8 prop @ 12,000 rpm : 10 X 12 = 120 mph maximum possible speed"
Okay let us see it together....
12 x 6 prop, 6 inch pitch - Theoretically 1 revolution will move the airplane 6 inches.
For 12,000 revolution per minute, it has move 12,000 x 6 = 72,000 inches per 1 minute.
In 1 hour, 72,000 x 60 minute = 4,320,000 inches per 1 hour.
We know 1 mile = 63,360 inch. Therefore 4,320,000/63,360 = 68.18 mph.
The second statement 12 x 8 prop - with the same calculation = 90.91 mph. But I believe they want to meant 12 x 10 prop, if so with the same calculation, 113 mph.
mmmm.... close but not exact. But in real life, if the airplane is not in diving mode, you will never achieve this speed. If however one can, wow... that guy will be rich because he can design an airplane with ZERO drag!!! hehehehe....