TM 5-6675-325-14
Factory determined RT val
provided with equipment.
NOTE
ue is given on Calibration Records Sheet
Alinement is performed as a check.
(7) Place planimeter near shape to be measured so that length of tracer arm
lies along imaginary line through center of shape.
Set wheels so that axles form 90
degree angle with tracer arm.
(8) Make practice trace to be sure tracer arm will cover area in one
operation.
(9) Determine area constant, C (multiplier), using the following formula:
c
= Area of constant
AT
= Area of test rule (given on Cal
provided with equipment)
RT
= Encoder count for each revolut
Sheet provided with equipment)
Sc
= Scale ratio
ibration Records Sheet
ion (given on Calibration Records
(a) Determine Sc by using the following formula:
Sc = CL x RL
Sc =
Scale ratio
CL
= Length constant (paragraph 5-6.2.32)
RL
= Counts per inch (given on Calibration Records
Sheet provided with equipment)
(b) Example:
Use given RL value (724) on Calibration Records Sheet and
CL value (0.018447) obtained from linear measurements on aerial
photographs (paragraph 5-6.2.ad).
Sc
= 0.018447 X 724 = 13.355628
SC2 = 178.372799
(c) Use values provided on Calibration Records Sheet for AT and RT.
For this example, the value for RT is 2157 and AT is 12.54.
The formula can now be computed on the calculator.
5-86