Plunging fire

[MikeBrough]

Morning, all. I searched but couldn't find anything on this topic. My knowledge of dynamics and mechanics is limited to first year mathematics at university - and that was 35 years ago - so I apologise in advance if it's a stupid question.

When we calculate the flight of a shell, we assume it's following a perfect trajectory based on the usual formulae, initial (muzzle) velocity, weight of shell, angle of guns, gravity etc). This allows us to calculate the distance travelled and likely angle of impact and this, in turn, allows us to calculate the likelihood of hitting side armour vs deck armour. All of the diagrams I've seen (and the formulae) show the perfect arc with the zenith being halfway along the total flight path and the impact angle being the same as the initial gun elevation.

Is this realistic? Will the shell not be slowing down all the time, through drag, meaning the second half of its flight (timewise) covering less horizontal distance than the first half? In turn, this means the angle of descent and impact being greater than the initial gun elevation. Basically, the arc looks more like a lob than a smooth mirror reflection about the mid-point.

Or am I talking rubbish and this is already taken into account in the formulae?

[MikeBrough]

Ignore me - I've just spotted a thread further down that covers this question.