[RocketsNW] Rockets Digest, Vol 15, Issue 22

[Paul Bogdanich]

At 08:17 AM 4/10/2009 -0700, you wrote:
>Sutton, 6th ed., p.493:
>
>M = (V^0.7)/2  for B-KNO3
>
>M in grams; motor free(i.e., not filled with propellant)volume V in cubic
>inches.
>
>How that scales to copper thermite you'll have to figure out for yourself.
>  Since professional practice usually involves rapid pre-pressurization of
>the motor, and the accompanying graph shows data for motors with free
>volumes from ten million to one thousand cubic inches, the amount of
>copper thermite for hobby motors will probably be much less than the
>formula indicates.  But what this shows is that it's not a linear
>relationship but rather a 0.7 power function of free volume.
>+McG+


True but the B-KNO3 is pelletized in a basket and in professional practice 
they control the flame front propagation by pellet size and geometry.