TM 11-6660-218-12
(2) Enter the densities for the remaining
plotted at the intersections of the hori-
zones, obtained from Chart ML-574A/
zontal and vertical lines.
UM, in column 1 opposite the appropriate
If the wind is from the west, select an
(3)
zone number on DA Form 4450.
origin at an intersection near the left
(3) After the required weighted densities
edge of the plotting board. If the wind is
have been determined and recorded, ob-
from the east, move to the right for the
tain the ballistic density values for each
origin so plots will not fall off the plot-
line by adding the weighted densities of
ting board.
each columns 1 through 15.
(4)
Center Scale ML-577/UM over the ori-
(4) Record these sums in the appropriate
gins for lines 1 through 15.
space under the line number.
Determine zone-weighted windspeeds
(5)
with the artillery tables, and plot the
d. Zone wind data using Rawin Set AN/GMD-
weighted values with Scale ML-577~UM
1 ( * ) requires the plotting of a pressure time curve
and procedures given in 9h (1) through
to establish the time at which the radiosonde set
(12) above.
reached the standard heights. Rawin DA Form
(6)
Complete the ballistic wind plot and
4469 is then completed as follows:
measure the ballistic wind direction and
(1) The pressure at the top of each zone,
speed. Record the data in columns 9 and
from Chart ML-574A/UM, is entered in
10 of DA Form 4469.
column 2.
(2) Time value, from the pressure time
35. Use of Electronic Observation Data
curve, is entered in column 3, opposite
a. The radiosonde data sheet is completed when
each zone number.
the information obtained from the radiosonde re-
(3) The angular data from the control re-
corder is entered on DA Form 4197.
corder tape is entered in columns 4 and 5.
(4) Horizontal data, which corresponds to
b. Ballistic temperature for a 15-line ballistic
the elevation angle for each standard
metro message is determined by use of the infor-
height, is determined from artillery ta-
mation obtained from DA Form 4197 and Chart
bles and entered in column 6.
ML574A/UM. The altitude pressure density is
(5) Zone winds are plotted; use the proce-
measured with the zone height scale, which is
dures described in paragraph 3-4g.
graduated in meters and indicates the thickness of
(6) After the zone wind plot has been made,
the standard artillery zones.
enter the distance traveled in each zone
(1) Plot the significant data from DA Form
in column 7.
4197 for each significant level on Chart
(7) Compute the time in zone and enter the
ML-574A/UM successive legs for a 15-
data in column 8.
Iine message.
(8) Measure the wind direction in each zone;
(2) Compute ballistic temperature, using
use Scale ML-577/UM, and enter zone
Chart MG574A/UM with the artillery
wind directions to the nearest 10 roils in
tables, and enter the data on DA Form
column 9.
4450.
(9) Compute the zone windspeed in knots and
(3) Report ballistic temperatures as percents
enter the data in column 10.
of standards, and enter a check in the
(10) Enter the surface wind measurement;
type of message being prepared.
use the hand velometer and enter the
(4) Complete ballistic temperatures for lines
data in columns 11 and 12.
1 through 15 and enter the sum of the
ballistic values on DA Form 4450.
3-6. Sound-Ranging procedures
The standard meteorological conditions for
c. Ballistic densities for all meteorological mes-
sound-ranging computations are based on a height
sages are computed and entered on DA Form 4450.
of 200 meters above the surface level, with a zero
The densities are read from Chart ML-574A/UM
windspeed, at 100 Centigrade. Speed of sound
and recorded on this form.
under these conditions is 337.6 meters per second.
(1) Enter the surface density in column 1,
a. Effective temperature for sound ranging is
after checking the block marked DEN-
determined from measurements of temperature
SITY GM/M3, to indicate the form iS
and relative humidity.
being used to compute density.
Change 8
3-14
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