368
14 CFR Ch. I (1–1–19 Edition)
Pt. 60, App. C
while focusing on the dominant frequencies.
Less emphasis should be placed on the dif-
ferences at the high frequency and low am-
plitude portions of the PSD plot. During the
analysis, certain structural components of
the flight simulator have resonant fre-
quencies that are filtered and may not ap-
pear in the PSD plot. If filtering is required,
the notch filter bandwidth should be limited
to 1 Hz to ensure that the buffet feel is not
adversely affected. In addition, a rationale
should be provided to explain that the char-
acteristic motion vibration is not being ad-
versely affected by the filtering. The ampli-
tude should match helicopter data as de-
scribed below. However, if the PSD plot was
altered for subjective reasons, a rationale
should be provided to justify the change. If
the plot is on a logarithmic scale it may be
difficult to interpret the amplitude of the
buffet in terms of acceleration. For example,
a 1
×
10
¥
3
g-rms
2
/Hz would describe a heavy
buffet and may be seen in the deep stall re-
gime. Alternatively, a 1
×
10
¥
6
g-rms
2
/Hz buf-
fet is almost imperceptable, but may rep-
resent a flap buffet at low speed. The pre-
vious two examples differ in magnitude by
1000. On a PSD plot this represents three dec-
ades (one decade is a change in order of mag-
nitude of 10, and two decades is a change in
order of magnitude of 100).
N
OTE
: In the example, ‘‘g-rms
2
’’ is the
mathematical expression for ‘‘g’s root mean
squared.’’
f. Table C2B, Motion System Recommenda-
tions for Level C and Level D Helicopter
Simulators, contains a description of the pa-
rameters that should be present in simulator
motion systems to provide adequate onset
motion cues to helicopter pilots. The infor-
mation provided covers the six axes of mo-
tion (pitch, roll, yaw, vertical, lateral, and
longitudinal) and addresses displacement,
velocity, and acceleration. Also included is
information about the parameters for initial
rotational and linear acceleration. The pa-
rameters listed in this table apply only to
Level C and Level D simulators, and are pre-
sented here as recommended targets for mo-
tion system capability. They are not require-
ments.
T
ABLE
C2B—M
OTION
S
YSTEM
R
ECOMMENDATIONS FOR
L
EVEL
C
AND
L
EVEL
D H
ELICOPTER
S
IMULATORS
a. ...........
Motion System Envelope
a.1. ........
Pitch
a.1.a. .....
Displacement ......................................................................
±
25
°
a.1.b. .....
Velocity ...............................................................................
±
20
°
/sec
a.1.c. .....
Acceleration ........................................................................
±
100
°
/sec
2
a.2. ........
Roll
a.2.a. .....
Displacement ......................................................................
±
25
°
a.2.b. .....
Velocity ...............................................................................
±
20
°
/sec
a.2.c. .....
Acceleration ........................................................................
±
100
°
/sec
2
a.3. ........
Yaw
a.3.a. .....
Displacement ......................................................................
±
25
°
a.3.b. .....
Velocity— ............................................................................
±
20
°
/sec
a.3.c. .....
Acceleration ........................................................................
±
100
°
/sec
2
a.4. ........
Vertical
a.4.a. .....
Displacement ......................................................................
±
34 in.
a.4.b. .....
Velocity ...............................................................................
±
24 in.
a.4.c. .....
Acceleration ........................................................................
±
0.8 g.
a.5. ........
Lateral
a.5.a. .....
Displacement ......................................................................
±
45 in.
a.5.b. .....
Velocity ...............................................................................
±
28 in/sec.
a.5.c. .....
Acceleration ........................................................................
±
0.6 g.
a.6. ........
Longitudinal
a.6.a. .....
Displacement ......................................................................
±
34 in.
a.6.b. .....
Velocity ...............................................................................
±
28 in/sec.
a.6.c. .....
Acceleration ........................................................................
±
0.6 g.
a.7. ........
Initial Rotational Acceleration Ratio.
All axes 300
°
/ sec
2
/sec
a.8. ........
Initial Linear Acceleration Ratio.
a.8.a. .....
Vertical ................................................................................
±
6g/sec
a.8.b. .....
Lateral .................................................................................
±
3g/sec
a.8.c. .....
Longitudinal .........................................................................
±
3g/sec
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