TM 10-1670-305-23&P
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AUTOMATIC RIPCORD RELEASE, MODEL 451
0004 00
THEORY OF OPERATION
The AR2 senses rate of fall and altitude above mean sea level (not above ground level). When
the AR2 falls through the altitude set on the altitude dial at a rate of fall of over 80 ft/sec, the
power cable will retract two inches (minimum) and at an initial force of 70 pounds. If the rate of
fall is at a slower speed, such as 70 ft/sec, the AR2 will not actuate.
When the AR2 is used on the reserve parachute, the main parachute must be fully deployed at
least 1,500 feet above the actuation altitude for the AR2. While in free fall, if the main parachute
opens within only a few hundred feet above the actuation altitude, the fall rate mechanism may
not have sufficient time to equalize pressure and deactivate. This could result in the deployment
of two parachutes, leading to problems associated therewith. If the fall is initiated below the
altitude set on the altitude dial, the AR2 will definitely actuate, and generally within 1,000 feet of
free fall.
