a. General.
The calculator permits estimation of yield when the illumination time is
known and when the flash-to-bang time (or distance from burst) and any of
the following parameters are known:
(1) Stabilized cloud-top angle.
(2) Stabilized cloud-bottom angle.
(3) Nuclear burst angular cloud width (measured at 5 minutes after
the burst).
b. Description.
Instructions for the use of the M4A1 Calculator are as follow:
(1) To obtain yield from cloud bottom or top:
(a) Align flash-to-bang time with elevation angle.
(b) Read yield on appropriate scale under pointer.
(2) To obtain yield from cloud width:
(a) Align flash-to-bang time with cloud width.
(b) Read yield under pointer.
(3) TO obtain yield from illumination time:
(a) Set pointer to illumination time.
(b) Read yield under pointer.
c. Sample calculations using M4A1.
(1) Yield from cloud width:
(a) Align 30 seconds on flash-to-bang time scale with 300 mils on
observed cloud width scale; read answer under pointer. Answer: 8 2KT.
(b) Align 35km on distance-to-ground zero scale with 180 mils on
observed cloud width scale; read answer under pointer. Answer: 50 2KT.
(2) Yield from fireball illumination time. This method of estimating
yield is to be utilized only when other methods of calculations are not
possible.
Determine fireball illumination time and read yield off yield
scale.
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CM5206
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