Activation of new aaa units - Air Defense Artillery

19.J8 DETERMINATION OF FIRING ERRORS FOR HEAVY AAA 31
c:-- ALL COURSES ARE PAftALLEL TO THE INOOM'". COURSE AND DISTAIfT
_ . __ .J fftOM THE I"-COMINe COURSE: A PREOETERMINED DISTANCE
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DEAD AREA
INCOMING COURSE .PASSES DIRECTLY OVER FIRING BATTERY)
Figure 2-Courses used to obtain the data for changes in
minimum range.
considered have a 360 degree field of fire, and their accuracy
is not affected by the azimuth of the target, it was
~ecessaryto study only one area of the sky with respect to
fieldof fire. Figure 2 shows the courses which were used to
obtain the data for changes in minimum range. The first
courseat each altitude was Hown directly over the batterv
giving the data on incoming targets. Succeeding course's
at each altitude were Ho\vnparallel to the first course and
at various minimum ranges. On each of the courses shown,
data were taken with each type of fire control, radar and
\'isual. Since the type fire control which a potential enemy
might use wo -generally be unknown, the values obtained
b averaging the results of the two groups were
considered of more value than either group considered
alone. The effects of changes in target speed were determined
by a combination of experiments on a limited
scale and application of the results obtained to all other
points for which experimental data with respect to target
speedwere not obtained. The requirement that an average
battery conduct the experiment caused some difficulty.
However, with normal turnover of personnel and replacement
by relatively inexperienced personnel, the possibility
of the battery becoming too highly trained to be considered
a\'eragewas overcome.
Data were taken on both firing and sim'ulated firing
courses. Simulated firing courses were necessary due to
safetyrequirements and the huge ammunition requirements
of an "all firing" problem. Errors of simulated firing data
Wereobtained by a comparison of true firing data vl.'ithfiring
data furnished by the director. True data for this compari-
SOnwere obtained by an electronic ballistic computer using
target present position data determined by phototheodolite
~ethods. The ballistic computer solves for future position
In terms of quadrant elevation and azimuth, and prints errorsbased
on the comparison with director data. ;'\0 data
on fuze errors \"ere compiled at this time, since the study
Wasmade assuming ~'ariabletime fuze conditions. Only
prediction errors could be determined by simulated firing.
:\ctual firinu \vas done with 11ledul1lical,ime fzced ammu--
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Ultlon,and bursts \\-ere then moved by computation to detennine
the points at \vhich bursts would ha\-e occurred if
variable time fuzes had been used. The points so computed
were used to establish errors in azimuth and quadrant elevation.
The difference between actual firing errors and simulated
firing ermrs is an increment of error due to ballistic
conditions and materiel and personnel errors. Considerations
which affect the size of this increment are (1) Parallax,
(2) Dither, (3) Additional Computer Circuit errors,
(4) Density and Muzzle Velocity Computer Correction
errors, (5) Firing table errors, (6) a group of other sources
of small errors which do not individually affect the result
but which collectively may be significant. It is a popular
misconception that the firing errors listed in the firing
tables are the only ones which should be expected when
firing at aerial targets. The firing tables list firing errors for
static problems only. The errors determined by this study
are for dynamic problems. This difference, or increment,
was obtained theoretically and added to the simulated firing
errors. The summation of simulated firing errors and the
computed increment was then checked against firing errors
obtained in actual firings. Agreement between the summation
and actual firing errors indicated that use of the summation
in lieu of actual firing errors was permissible. This
use of a measured prediction error plus a computed firing
increment error is further supported by a comparison of the
size of the two components. The comparison shows that
prediction error makes up the major portion of the whole
firing error. /
Simulated firing has the distinct advantage over actual
firing in that data are furnished every second instead of only
when bursts occur. This materially decreases the number
Figure 3-An example of total errors with the erroneous center
of impact errors resulting from using a block size too
small to include a complete cycle.
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