July-August - Air Defense Artillery School

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) STEREOSCOPIC VIE\VER 29
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CENTER MIRRORS I
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~ "'IRROR i' i' WING MIRROR
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6 POWER
BINOCULARS
p!ertaken to determine the practicability of the instrument
determining "overs" and "shorts" both as applying to soed
"line" shots and those in which neither obscuration
r silhouette occurred. For this purpose the actual slant
ge of the target was periodically determined by the
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rd section employing standard bi-Iateral procedure. A
~arate record was maintained covering the slant range
ling actually used in the director for the firing of the
eral shots of the course. The sensings on each shot as
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tedby the observer on the stereoscopic viewer were like-
'se made a matter of record. For the purpose of comparison
wasassumed that if the slant range setting used in the dilOr
for a given shot was appreciably in excess of the
ualslant range as determined by record section, an "over"
ld be reasonably expected and in all probability ocred'
Conversely a "short" would likely result from an 01'ile
situation. Analyses and comparison of the results for
courses, averaging about eight rounds per course, were
de by the officers in charge of record section who refled
that:
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a. In about 4% of the shots the range comparisons were
such as to permit of certain determination as to the
se of the shots and it could not be stated that the sensings
the stereoscopic observer were definitely correct or in
~ r.
, h. 4% of the stereoscopic sensings may have been and
bably were in error.
c. 92% of the sensings by stereoscopic observer were in
rd with the range result which might be reasonably cxled
from comparative values of director and actual slant
ge.
During 37mm fire on ~larch 31, with non-explosive proiles,
the stereoscopic observer noted and called a "hit"
h descriptive remarks as to its precise location. A similar
ing was made shortly thereafter with respect to a sec-
~ "hit." His observations were indisputably confirmed
jrben the target was dropped immediately afterward. Later
the same day the observer's serisings with respect to two
er hits were similarly confirmed.
While results obtained in the conduct of this test (which
limited to some 4,000 rounds) cannot for a variety of
ns be considered as conclusive, it would appear that
observer having the advantage of both separation and
nification can distinguish with considerable accuracy
Ween "overs" and "shorts" and in so doing is not deent
upon "line" shots as the only certain guide for
range adjustment. An observer having the benefit of aided
vision can thus take full advantage of "line" shots to a
better extent than he could without such assistance and in
many cases can operate without the benefit of "line" shots
which unfortunately do not in practice occur with the uniform
regularity inferable from the text of certain training
publications and instruction manuals.
It is known that consideration has been given to the
adoption of equipment which would permit of instantaneous
slant range determination and incorporating this data
into the director operation thus eliminating some of the
present difficulties of initial range estimation and subsequent
range manipulation. Lacking such equipment it is
believed possible to increase greatly the efficiency of range
setters by providing simple depth perception mechanism as
a part of the director. This could be connected in such
manner as to follow the target through the normal operations
of lateral and vertical trackers and the range setter
could adjust the sense and magnitude of his leads with
greater precision and promptness than is now possible. Such
mechanism would not require determination of lineal ranges
and lead adjustment, except perhaps for initial range setting,
would lose much of its numerical significance and be
handled in terms of trail or precession of shots. If the angular
rates generated by tracers are correct (an assumption
upon which we must proceed after sufficient crew training),
an excessive lead is an indication of over range and
vice versa. For any given angular rates an increase in the
director range setting will result in increased angular leads
and as a consequence the range setter can correct trail (a
short) by turning his range wheel clockwise and can correct
precession (an over) by counter clockwise movement, without
knowing or being particularly concerned with the numerical
values of the range set.
.There should not be overlooked the often repeated injunction
against the practice of "creeping the range," in
which the setter attempts to approximate the progressively
changing range which would be required for interceptions
on different portions of a constant speed rectilinear course.
This procedure is indeed hazardous, particularly so if attempted
with unaided vision, and would be difficult even
with the detectivity afforded by the suggested stereoscopic
equipment. It is thought preferable to follow the present
authorized procedure of range interception utilizing the
capabilities of the instrument to detect readily any sizeable
errors in either initial or subsequent range setting and seek
for more frequent range interceptions than can be safely attempted
on the basis of unaided vision. The procedure will
in general permit range jumps in smaller increments with
resultant decrease in dead areas in which (due to range
divergence) no hits may be expected.
Some may claim that this procedure would call for a degree
of artistry beyond the ability of the average range setter.
This may be the case although equipment has not been
available to test the possibilities. In any event, and without
regard to the precise technique followed in range adjustment,
the potentiality of the gun and ammunition has not
been fully exploited due to lack of visual aids and can undoubtedly
be furthered if the range setter be provided with
equipment designed to meet his principal problems, ---
"knowing where they're going."