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Old 07-15-2014, 10:45 AM   #31
sir_pudding
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Default Re: [Basic] Skill of the week: Artillery (and Forward Observer)

Quote:
Originally Posted by Kromm View Post
There has to be some middle ground. Extremely light mortars such as this one are meant to be deployed and fired almost on the run. Rheinmetall, the current manufacturer, had videos online a while back that illustrated it in use. A man appeared to run up, plonk the thing on the ground, pop a bunch of rounds at targets 300 to 600 meters away, and correct fire entirely on feedback from another guy. That might be manufacturer hype . . . I really don't know. But that's the only kind of mortar fire I've ever used in my campaigns, since any mortar heavy enough not to be a personal weapon in a really light squad of irregulars isn't on the menu for the sorts of adventures I run.
Quote:
Originally Posted by Ulzgoroth View Post
If the observer, gun, and target are approximately colinear, then the Cartesian to polar problem is pretty much as simple as fredtheobviouspseudonym suggested. Normally that can't be assumed, of course, but if the mortar is a squad (or adventuring party)-level asset it might be used that way.
Quote:
Originally Posted by The Colonel View Post
If it helps, the old British 2" mortar was pretty much aimed by dead reckoning - you lined it up at the target, judged the distance and set the angle of the barrel by a combination of judgement and guesswork. You then fired a bomb and adjusted for fall of shot - but then you only had a range of about 500 yards and weren't likely to be using much in the way of forward observation.
Yes, you can fire mortars like this and many light mortars are designed to make this very easy (like the M224 with it's assault plate, firing trigger and spirit level). However this is called "direct lay" and you aim in on the target itself rather than an aiming stake. In GURPS according to the Basic Set, and confirmed by you Sean, this uses Guns (Grenade Launcher) rather than Artillery (Cannon).


Quote:
Originally Posted by Kromm View Post
I've never run an adventure where that wasn't the case for a 51mm to 60mm infantry mortar. As I said, the observer is just ahead of the mortarman; he might be prone at the summit with the mortar set up literally at his heels on the reverse slope, like this:
X

















--O--
M

Where X is the target, O is the observer, the dashes indicate a ridgeline, and M is the mortarman. The observer is still needed because the mortarman wants to remain in defilade to avoid having his head blown off, and can't easily operate a mortar while prone and unmoving. The prone, stationary, camouflaged observer effectively serves as an aiming periscope, but since the mortarman is relying on relayed targeting information, the skill is still Artillery, not Gunner.

I have no idea how common that arrangement is, but it doesn't seem unrealistic, and it's also consistent with how a tiny team of irregulars might operate.
In real life, you don't do indirect fire without an FDC even with closely colocated observers. I'm not sure how the situation you describe even works though because without aiming stakes or visibility on the target what is the gun crew aiming at?
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