Posted: Jan 20, 2018 11:21 pm
by Calilasseia
I've just learned of the existence of a missile system called the RIM-116 Rolling Airframe Missile, and there's an aspect to this system that puzzles me.

Apparently, the missile rotates in flight about its longitudinal axis, in much the same manner as a bullet or a shell fired through a rifled gun barrel. Which strikes me as a pretty odd thing for a missile to do.

One of the reasons that rifling is used to make a ballistic projectile spin, is to increase stability, and increase resistance to external forces causing the projectile to deviate from its intended flight path. Which makes sense for a projectile that you cannot steer in flight.

But a missile is, by definition, a guided weapons system, with built in capability for in-flight manoeuvring. One of the advantages of a guided missile, is that it can turn to follow targets performing evasive manoeuvres. Adding extra moment of inertia about the longitudinal axis, which would increase the effort the manoeuvring system had to exert to turn the missile, seems to me in part at least to defeat the purpose of having a guided missile in the first place. So what's the point of this?