Figure 4-21.—Number of flight lines nomograph.
is 1/10,000, the distance between flight lines drawn on
the chart is 64,800
1/20,000, or 3.24 inches. Since it
is difficult to measure the flight-line distances
accurately, a multi-finger divider should be used (fig.
4-22).
To use the multi-finger divider, first multiply the
distance between flight lines by the number of fingers
on the divider. This will give you the total flight-line
plot width. Using a ruler, place the first divider finger
on zero and the last divider finger on the mark
corresponding to the total flight-line plot width. The
individual fingers of the divider automatically space
themselves to the correct distance for each flight line.
The multi-finger divider may then be used to lay out the
flight-line plots.
INTERVAL BETWEEN EXPOSURES
You must convert the aircraft ground speed to feet
per second to determine the exposure interval or
frequency between frames. The conversion factor for
Figure 4-22.—Multi-finger divider.
4-23
