EFFECT OF NVG MOUNT AND SHROUD ANGLES ON
NIGHT VISION GOGGLE ORIENTATION RANGES
Brian Higginson, Martin Fultot, Lauren Brewer, and Jesse Smith
Given the wide range of shapes and
designs of military helmets, night vision
goggle (NVG) shroud angles vary
considerably. The same variability exists
with NVG mounts as well, with some
mounts having a greater deployment angle,
and/or greater range of adjustability, or tilt,
than others. Given these differences across
helmet designs/shroud angles, and NVG
mounts, the potential range of NVG
orientation relative to the helmet may vary,
depending on helmet/mount combinations.
It is important to understand how these
factors influence NVG orientation, and more
importantly, where the user-preferred
orientation falls within these bounds.
This preliminary study was conducted to
quantify the range of shroud angles resulting
from various helmet designs, range of NVG
mount deployment and adjustability/tilt angles,
and where user-preferred NVG orientation
falls within the range of NVG orientations
possible given the different helmet/mount
combinations.
Warfighter Systems Integration Lab, Galvion Ltd, Portsmouth, NH
RESULTS AND DISCUSSION
DISCUSSION/CONCLUSIONS
INTRODUCTION
Figure 4. User preferred line of sight relative to the range of NVG adjustability across the helmet
and NVG mount options.
Figure 1. Measured angles: Helmet Orientation (O
HEL
), NVG Orientation (O
NVG
),
Max NVG Angle (Θ
MAX
), Min NVG Angle (Θ
MIN
), Shroud Angle (Θ
SHR
),
Deployment Angle (Θ
DEP
).
• Shroud angles varied from 14-34° for the PRO and ECH
(respectively), with the CAI falling in between at 24°.
• Adjustment range was 5° greater for the NOR mount than
the WIL (20° vs 15°, respectively),
• Deployment angle (from the stowed position) was 5°
greater for the WIL mount than NOR (115° vs 110°,
respectively).
• Preferred angle for the ECH fell at the lower end of the
adjustability range for both the WIL (-1°, within -4° to 10°
adjustment range) and NOR mount (-1°, within -3 to 16°
adjustment range
• Preferred angle for the PRO helmet tended to fall on the
upper end of adjustment ranges for the WIL (-7°, within -
23° to -1° adjustability) and NOR mount (-8° within -21° to -
2° adjustability).
• Preferred angle for the CAI helmet was the most centered
in the adjustability range for both mounts of the helmets
tested (WIL: -6°, within -13° to 0° adjustability; NOR: -5°,
within -12° to 8° adjustability)
• Of the six helmet/mount combinations tested, helmets with
the greatest shroud angle resulted in preferred NVG
positions closer to the lower end of overall NVG
adjustability.
• Helmets with the steepest shroud angle resulted in
preferred NVG positions closer to the upper end of overall
NVG adjustability.
• Helmets with an intermediate shroud angle (24°) resulted in
preferred NVG positions that were more centered in the
overall range of adjustability, allowing for more user
variability and adjustability in the lower and upper ranges.
• In general, preferred NVG orientations fell between 0° and
10° below the longitudinal axis of the helmet rail.
• Based on the current data, and the most commonly used
NVG mounts, a helmet shroud angle between 20-25º
appears to be most ideal to center the user-preferred line of
sight within the overall NVG mount range of adjustability.
CAI ECH PRO
20° 15°
PURPOSE
METHODS
APPROVED FOR PUBLIC RELEASE
Equipment tested:
• Helmets: Enhance Combat Helmet (ECH),
Caiman (CAI), and Prototype boltless
helmet (PRO)
• NVG mounts: Wilcox G24 (WIL) and
Norotos Rhino (NOR)
• NVG’s: PVS-31
NVG adjustment ranges were calculated and
expressed relative to the long axis of the
helmet accessory rail for each helmet/mount
combination.
Within this adjustment range, preferred NVG
orientation was established from six users.
ECH
CAI
PRO
NOR
WIL
Figure 2. Shroud angles (from
vertical) of the three helmets tested.
Figure 3. Deployment angle and adjustment
range of the two NVG mounts tested.
Figure 4. Visualization of the possible NVG orientations based on the
helmet shroud angle, NVG mount deployment angle, and NVG mount tilt
for each of the helmet/mount combinations.
PRO ECH
CAI
WIL
NOR
Angle (
°)
