Finned projectiles that are intentionally spun are known to become locked i
n at a resonance condition where the roil rate matches the pitch/yaw freque
ncy. This phenomenon, called roll lock-in, results in an amplification of t
he trim angle, which can lead to yaw instability. A less severe phenomenon
is that of transient resonance where the roll rate locks in at resonance br
iefly before continuing to build up to the design value. However, the trim
amplification during the brief period of resonance may be sufficient to des
tabilize the projectile. In this paper, the problem of transient resonance
for finned projectiles with a centre-of-mass asymmetry is studied. Numerica
l simulations are used to illustrate transient normal and reverse resonance
. No yaw amplification is seen in both cases; rather the absolute value of
the complex angle of attack shows a drop during passage through resonance.
It is suggested that this is a general feature of the yaw response of finne
d projectiles undergoing transient resonance.