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OPERATIONAL
LEG CLEARANCES WITH THE MAIN INSTRUMENT PANEL
PURPOSE
The
purpose of these measurements is to determine the longest leg lengths to obtain
operational knee and shin clearances with the main instrument panel.
DISCUSSION
Interference
with the main instrument panel and switch guards, controls, and other structures
extending aft of the instrument panel, are associated almost exclusively with
the upper ends of the range for Buttock-Knee Length. However, total leg length
also has an effect. For that reason
data should be gathered on a range of values for combined Buttock-Knee Length
and Sitting Knee Height ("combined" leg length or "ComboLeg").
If subjects representing the maximum values for these leg dimensions are
not available, larger Buttock-Knee Lengths can be simulated by blocking to a
maximum of one inch behind the buttocks. A
corresponding maximum of one inch of aft adjustment in the rudder pedal carriage
can be used to simulate larger values for ComboLeg.
Caution must be exercised so that these artificial means of simulating
larger body dimensions do not exceed the maxima for these dimensions in the
population.
Interference
with the main instrument panel may be found to occur with the feet on neutral
rudder pedals as well as during the extremes of rudder pedal motion.
All of these conditions are examined.
PROCEDURE
The
subject, dressed in flight suit and boots, is installed in the seat, the
harnesses are snuggly adjusted and the inertia reel locked with the subject
firmly back into the seat.
Data
are first gathered at the full-down seat position. The rudder pedal carriage is adjusted to the most forward
position that permits the subject full-forward throw at maximum leg reach -
usually with the knee fully extended. The
subject should be able to operate the rudders and brake without squirming either
hip forward. If the pedal carriage
is thereby adjusted to its full-forward position, this fact should be noted.
The
subject is instructed to engage the rudder pedal bar at neutral rudders with the
balls of the feet, rather than with the heel catch.
This gives the subject a small amount of additional reach.
Measure
the distance between the leg (at the knee or shin) and the main instrument
panel, and/or protruding controls and control guards.
Measurements
are made on both the active and passive legs with full rudder throw.
Measurements
are repeated with the seat at one-inch intervals to full-up.
MEASURING SHIN CLEARANCE WITH THE MAIN INSTRUMENT PANEL.
Click
on
FIGURE
for a proposed data
form.
ANALYSIS
AND RESULTS
Generally,
there is a direct relationship between increases in Buttock-Knee Length and
reduced leg clearance to the main instrument panel. Sitting Knee Height has been found to have only a minor role
in affecting such clearance.
Since
Buttock-Knee Length is the body dimension most closely associated with leg
clearance, data analysis consists of adding the clearance forward of the knees
or shins to the subject's Buttock-Knee Length to obtain the threshold clearance
value. The worst-case rudder pedal
position, neutral or full right or left rudder, is reported. The averages of all such values are calculated.
The maximum Buttock-Knee Length to clear the instrument panel in the T-37B
is 29.0 inches.
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