74 Chadwick-Helmuth Company, Inc.
Chapter 5 - General Operation
Weight Per IPS -
The weight entry in the Weight Per IPS screen must
be the same as the weight required to cause a move line of 1.0 IPS (see the
definition of move line in the “Glossary” on page 161).
Edit the weight (in grams), by using the alpha-numeric keypad, enter the
most significant digit first, followed by successively less important digits.
For example, to achieve a perfect balance from 1.0 IPS, a propeller might
require 47.5 g. Using the numeric keypad enter the appropriate numbers
in this order,
4, 7, 5
NOTE: It is not necessary to enter the decimal.
If the user is not sure about the weight sensitivity, be conservative, that is,
use a lower number. This action yields more conservative weight
corrections for the propeller. On subsequent runs, these corrections
automatically become calibrated by the Vibrex unit’s Automatic Chart
Correction feature.
NOTE: Automatic calibration only occurs if the user has set the
Autocorrection feature to <ON>.
Phase Correction -
The difference in angle between when the event
occurs and when it is sensed by the Velocimeter. Keep the following
important facts in mind when working with the Vibrex unit and phase
correction:
• The Vibrex unit defaults to the 12:00 direction for phase, unless the
user has entered a different number.
• The user can accommodate most of the mounting differences from
engine to engine by using the Chadwick-Helmuth Propeller
Protractor. For instructions on how to use this tool, see
Section 5.4.3.2 “Using the Propeller Protractor” on page 82.
• The phase angle derived by the Vibrex unit is a combination of the
direction of sensitivity of the Velocimeter, the azimuth from the
photocell system, and the phase correction.
• The farther the Velocimeter is from the rotating item, the greater the
likelihood becomes that a phase correction is necessary.
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