“RUSSIAN ARTILLERY JOURNAL.” 
JANUARY , 1891. 
“ON THE ANGULAR VELOCITY OF ROTATION OF AN 
ELONGATED PROJECTILE.” 
BY 
CAPT. N ; ZABUDSKI, Russian Artillery of the Guard. 
Precis translation by 
Major G. T. Kelaart, R.A. 
I. 
For the purpose of increasing the effect of fire in siege warfare, 
fougasse shells with very large bursting charges are now being 
introduced. 
For a given weight, the shells are designed to contain the maximum 
quantity of explosive, their length . coming up to 6 calibres. 
Experiment shows that, in service guns with the present twist, increase 
of length of projectile, beyond a certain limit, diminishes the accuB&cy. 
We will here endeavour to investigate the proper twist for a given 
projectile. 
The method of treatment of problem is as follows :—the tangent at 
any point to the trajectory, described by the 0. of 6r. of projectile, is 
supposed to be fixed, and the axis of figure is supposed to have a conical 
motion round it, during which the angle S between the axis of figure 
and the fixed tangent changes periodically.* 
To avoid these oscillations (nutations) which, when of appreciable 
magnitude, influence, prejudicially, the accuracy of shooting,! and in 
order that the axis may describe a circular cone (precession) round the 
fixed tangent, the following conditions must be fulfilled, from which 
is deduced the formulae (11), fixing the twist for a given shell and for 
given magnitude of couple of air resistance. 
Experiments showed that, to obtain accuracy, the twist at muzzle must 
not be less than a certain limit, which is approximately that obtained 
from the formulae (11) or (17), after making certain suppositions 
regarding the couple of air resistance. 
* The Author, regarding this conical motion, refers to N. Majevski’s “ Traite de 
Balistique,” p. 163. 
1 And also adds “With individual rounds the time of reaching a defined point 
of trajectory must inevitably vary. Since the period of oscillation 
Majevski’s “ Traite de Balistique,” p. 163) is not great, the magnitude of 5 will 
always vary at each round.” 
3. VOL. xix. 
18 b 
