July-August - Air Defense Artillery School

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The formula for the lateral correction is:
51
dA=---
COS £1
T)pical example
To illustrate the use of the aboye method, consider the
oIlowingtrial shot problem for a 3 inch battery using ~ 142
hell and ~ 143A3 fuze. The pertinent trial shot data reuired
for the solution of the problem by this method is
" follows:
~ison the right
1= 5000 yards
l = 5000 )'ards
L = 1207 mils
£1 = 800 mils
f:! = 966 mils
Assumed i\ IV
= 2850 ftlsec
Average observed deviations
From 01: Above 7 mils
From 01: Left 8 mils
(Slant plane)
From 0:: Short 20 mils
(Slant plane)
The solution of this problem by this method is as follows:
Cl = 3.03 (See table II)
3.03 _
C~ = 0.707 X 2.46 = 1.7)
3.03
C3 = 0.812 X .926 = 4.03
TABLE I
Then .6i\I\' = T (3.03) (7) + (1.75) (8)
(4.03) (20) = J- 21 T 14 - 81 = -46 feet per
second
The developed muzzle velocity is then 2850 - 46 =
2804 feet per second
The vertical correction required to bring the shots to
the !\IV line is - 8 - 46 (.03) or down 8 mils
The lateral correction required to mm'e the bursts into
8
the plane of the target is 0 -0- or right II mils .
.I I
Derivation of formulas
Cl FACTORSFon 901\11\1AA GUN
HE SHELL M71, FUZE M43A3
The key to the above method of solution lies in a complete
understanding of the d%H factor for ballistic corrections
as given in the graphical firing tables. Referring to
figure I, the trial shot point is at T and the burst at B. The
line BK is drawn at right angles to the line of position. The
length of the line PK in altitude or the length of the line TP
in range determine the length of the line TM or the muzzle
velocity correction. If the muzzle velocitv deviation TM
was 100 feet per second the length of the line PK would be
(d%H factor) (H) and for a muzzle velOCitydeviation of
I foot per second, the length of the line PK would be
H
(d%H factor) 100. Likewise the length of the line TP for
10000 8.77 6.58 5.26
9000 12.I 5 8. I I 6.08 4.88 4.06 3.48
8000 11.10 7.42 5.55 4.46 3.70 3.18 2.86
.!:
... '"
>.:
7000
6000
5000
17.10
14.30
9.72
8.55
7.15
6.49
5.72
4.77
4.88
4.28
3.57
3.89
3.43
2.94
3.34
2.94
2.45
2.94
2.59
2.17
2.65
2.34
1.96
2.43
2.15
1.79
2.00
1.67
.- 4000 11.42 5.71 3.81 2.94 2.42 2.02 1.79 1.62 1.48 1.38 1.30
:..>
-g 3000 8.58 4.29 2.94 2.27 1.88 1.57 1.38 1.25 1.15 1.07 1.01
-= 2000 2.94 2.02 1.56 1.25 1.07 0.95 0.86 0.79 0.74 0.70
< 1000 I.Il 0.83 0.67
8000
7000
~ 6000
" 5000 13.50
r 4000 10.52
~ 3000
2000
'- 1000
-=
-:::::
1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 IlOOO
1000
11.42
10.00
8.35
6.75
5.40
4.05
2000
Horizontal Range in Yards
TABLEII
Cl FACTORSFOR3 INCHAA GUN
HE SHELL :M42, FUZE M43
7.62 5.88
6.67 5.15 4.24 3.77
5.72 4.42 3.64 3.24 2.86
4.63 3.58 3.03 2.69 2.38 2.24
3.70 2.78 2.35 2.08 1.91 1.79 1.71
2,78 2.08 1.77 1.57 1.43 1.34 1.28
1.80 1.39 I.l4 1.01 0.96 0.93 0.89
0.69 0.57 0.50 0.48
3000 4000 5000 6000 7000 8000 9000
Horizontal Range in Yards