And I believe the bearing and elevation are given relative to an aiming point. Sometimes it’s a stake in the ground that the sight is fixed on. An offset in elevation and azimuth is given from this stake. Then after the correct settings are found, all guns, which are close together, aim at the same aim point using the same elevation and azimuth settings.
As a macabre aside, the silver and gold painted insignia bars that 1st and 2nd Lieutenants started out wearing on the front of their helmets in WWII were soon referred to as “aiming stakes.”
Anyplace out-of-sight. It becomes fairly obvious when you are under observation, and the object then becomes to kill the observer before he sends the final corrections.
You seem to have identified the major reason forward observer duty is not very popular. My dad was a gunner in WWII. FOrward Observers were abbreviated to FOOs. Gunners quickly appended an L at the end as a comment on the wisdom of those volunteering for this duty.
Last things first - yes, in general more than one round is needed for adjustment, but nothing much changes in principle. Just rinse and repeat.
It’s all about precision in knowing where the guns are and accuracy in knowing how that position relates to the observer’s position. Typically, the battery center grid is sited using GPS data with long time-averaging, so that point is known to a precision of about a meter. Each gun’s position is then determined from battery center using surveying equipment (for greatest accuracy) or using separate GPS data (which is fast, but less precise, as random errors accumulate on each gun’s positioning instead of just on the BC grid.) This ensures precision.
Accuracy is obtained by what is called a ‘registration’ mission, in which the observer identifies a target that can be precisely located on his map - something like a road junction or a trig point. By adjusting on to this, it is possible to adjust out any error in the position reported by the guns relative to the map grid. If - when the observer orders fire for effect on the registration mission - any of the rounds falls away from the target point, the observer will then order the guns to fire individually so he can determine which gun is not firing to the target. The battery can then determine why this is the case, and hopefully fix it - this eliminates errors in accuracy due to the individual guns.
The result of all this is that when procedure has been followed correctly, the only factors affecting the accuracy of the barrage relative to the target are atmospheric conditions between the battery and the target and the accuracy of the firing data sent down by the observer. Both of these are the same for all of the guns being used, so only one gun need be used in adjustment.
Note that in war-time, batteries often follow the adjustment procedure firing with all of their guns. This is primarily because the enemy is least prepared for the first rounds that fall, so if you’re going to hit anywhere near them it’s worth hitting them hard.
This used to be the case: the aiming stake served as a reference to relate the gun’s bearing to a known compass bearing, using gear similar to a surveyor’s theodolite. As far as I know all US and UK artillery is now fitted with inertial navigation gear, which means that they have an accurate compass built in and this procedure would only be necessary in the event of INS failure.
Similarly, all guns would only fire using the same data in an emergency firing situation. This generally arises when the only battery available for an urgent mission is in transit - it will pull off the road, keeping the guns close together, fire the mission, then go back to travelling. For any long term gun emplacement, concealment and security demands that the guns are spread by at least 50 meters one from another, so it becomes necessary to take their individual positions into account.
I thought the accuracy of an INS degraded over time with gyro drift, and that an INS had to be “zeroed” every few hours/days against a GPS to retain its utility. I know that INS is good enough for ICBMs, which only travel for about a half-hour and may have poor access to GPS in wartime. I also know INS is used on submarines, but that they have to surface to take GPS readings occasionally. I would think that the ubiquity of GPS would make the INS a convenient backup rather than a primary position system… am I missing something?
I’m not an expert on this aspect of artillery at all, so take with a grain of salt. As I understand it, the position reckoned by INS systems does degrade over time, but their compasses are good. The position error arises primarily from inaccuracies in the distance travelled measurements, as I understand it: when deployed, one re-zeros against GPS at intervals specified by distance travelled, not time elapsed. I’ve seen guns fired with INS that have the wrong grid, and they still fired on correct bearings (as checked by the safety officer with a compass).
Further follow-up - it’s just occurred to me that one re-zeros against GPS only: i.e. with no compass information. With this in mind, and knowing that NATO artillery is damn good at its job, I presume that INS compasses are good over time.
Seems like a good plan. However, if I were a gun captain, after I got the proper sight line established I think I would pick a local aiming point just in case.
Having worked in the field of artillery I can answer the question regarding the answer of “fire for effect”. This is a term that is a euphemism for firing with an intention to psychologically affect the enemy rather than to simply kill them.
In firing for effect you may have the shells explode at a particular height above the ground so as to have to strongest psychological effect, or you may deliberately fire at a low angle to have the explosion spread at ground level and “take legs off at the kneecaps”.
Since it appears this thread was answered correctly eight years ago, there seems to be little point in reviving it. If there are further unanswered questions a new thread may be opened in GQ.
