US Artllery - Fire Patterns (Sheafs)

US Artillery Fire Patterns - Page Title
FIRE PATTERNS

 

INTRODUCTION FUSES & AMMO
TARGETING FIRE DOCTRINE
FIRE SUPPORT BASES OBSERVATION
FIRE TYPES ARTILLERY TO&E'S

Sheafs

A sheaf is the planes of fire of a group of weapons.

Parallel Sheaf
Parallel sheaf occurs when you aim all the weapons in the battery the same direction and angle. Disregarding dispersion, the shells will land in the same pattern as the guns are set up. This is the easiest sheaf to do since all guns use the same firing orders.

Regular Sheaf
Regular sheaf is when the shells are intended to land in a line with regular lateral spacing. This may, for instance, require the gun in the back of the battery to fire a little higher than the one in the front. This line usually runs perpendicular to the line between the guns and the target.

Open Sheaf
Open sheaf is a regular sheaf where the spacing is chosen so the sheaf has maximum width (given the burst area of each shell) without any gaps in between. This spacing is somewhat smaller than the width of a single shell burst to accomodate a small amount of lateral dispersion.

Heavy artillery usually uses open sheaf!

Converged (or Point) Sheaf
Converged (or point) sheaf occurs when all the guns are corrected to hit the same point. Also known as Precision Fire. Converged fire is called for to destroy a point target, a densely-packed target, or for point interdiction (such as on a bridge or crossroads).

Unusual Sheafs
The normal shape for a sheaf is a line perpendicular to the line-of-fire. Specially-shaped sheafs can be arranged under certain circumstances, such as strangely-shaped targets, point targets, barrages, etc, but this would be the exception. Individual gun corrections for normal sheafs can be handled by the battery itself; for special sheafs, the calculations are done at the Fire Direction Center.

Preplanned barrages, which would be planned well before the start of a game, would be more flexible in this respect in that there is plenty of time to do all the complex computations.

 


The Sheaf/Volley Tables

The following interesting tables are taken mostly from US manuals, with some of the time numbers being derived from ROF numbers elsewhere. The first table is the statistics for a single battery of size 4 or 6 guns, with open or converged sheaf. Area dimensions are in yards. Volleys is the number of volleys necessary to suppress troops in the area of impact, while rounds is simply Volleys times Number Of Guns. ROF 1 is the rate-of-fire during the first four minutes, when the guns are preloaded for the first volley. For longer-term fire, the ROF is greatly decreased due to ammo handling and gun cooling considerations. Time is derived by taking the number of shells divided by the ROF numbers, as shown by the ROF 2 column, and is given in minutes and seconds.

 

SINGLE BATTERIES

105mm Howitzer
Battery
Size
Sheaf
Type
Area
(W x D)
Volleys Rounds ROF 1 Time 1 ROF 2 Time 2

4 Converged 75 x 100 3 12 16 0.45 6.6 1.49
4 Open 150 x 100 6 24 16 1.30 6.6 3.38
6 Converged 75 x 100 2 12 24 0.30 10 1.12
6 Open 200 x 130 6 36 24 1.30 10 4.48

 

155mm Howitzer
Battery
Size
Sheaf
Type
Area
(W x D)
Volleys Rounds ROF 1 Time 1 ROF 2 Time 2

4 Converged 100 x 100 3 12 8 1.30 2.7 4.30
4 Open 250 x 100 8 32 8 4.00 2.7 12.00
6 Converged 100 x 100 2 12 12 1.00 4 3.00
6 Open 300 x 130 6 36 12 3.00 4 8.00

 

8" Howitzer
Battery
Size
Sheaf
Type
Area
(W x D)
Volleys Rounds ROF 1 Time 1 ROF 2 Time 2

4 Converged 150 x 100 3 12 6 2.00 2 6.00
4 Open 380 x 100 7 28 6 4.40 2 14.00

 

Battalion Fire Table

When an entire battalion fires, the batteries can choose to put all their sheafs on the same point, or to spread their sheafs downrange so there is some or zero overlap. The following table shows the statistics for various weapons with three batteries each of four or six guns, with converged sheaf (laterally as well as longitudinally) and open sheaf with different amounts of sheaf overlap. With range spread 1, the sheafs have no overlap but are adjacent to each other.

Weapon Pieces Sheaf Range Spread Area (W X D) Volleys Rounds

105mm Howitzer 12 Converged 0 150x150 3 36
105mm Howitzer 12 Open 0 200x200 5 60
105mm Howitzer 12 Open 1/2 200x250 6 72
105mm Howitzer 12 Open 1 200x350 9 108
105mm Howitzer 18 Converged 0 150x150 2 36
105mm Howitzer 18 Open 0 250x200 4 72
105mm Howitzer 18 Open 1/2 250x250 5 90
105mm Howitzer 18 Open 1 250x350 7 126
155mm Howitzer 12 Converged 0 160x150 2 24
155mm Howitzer 12 Open 0 300x200 5 60
155mm Howitzer 12 Open 1/2 300x250 6 72
155mm Howitzer 12 Open 1 300x350 9 108
155mm Howitzer 18 Converged 0 160x150 2 36
155mm Howitzer 18 Open 0 350x200 4 72
155mm Howitzer 18 Open 1/2 350x250 5 90
155mm Howitzer 18 Open 1 350x350 7 126
8" Howitzer 12 Converged 0 200x150 2 24
8" Howitzer 12 Open 0 400x200 5 60
8" Howitzer 12 Open 1/2 400x250 6 72
8" Howitzer 12 Open 1 400x350 9 108

 

Multi-Battalion Fire Table

If multiple battalions attack a target, the effect and beaten zone is larger. The smaller areas on the following table are if careful correction is done.

Battalions Weapon Battery Size Area

2 105 Howitzer 4 200x250 to 250x300
2 105 Howitzer 6 300x250 to 350x300
2 155 Howitzer 4 250x250 to 300x300
2 155 Howitzer 6 350x250 to 400x300
3 Mixed   350x300 to 400x400

 


Courtesy of Daryl Poe


 

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