SIM University 2012 - Christie · SIM University 2012 Glass Mirror Technology that is Reliable,...

SIM University 2012

SIM University 2012

Glass Mirror Technology that is Reliable, Cost Effective & Versatile

October 23, 2012

Justin KnaplundChief Scientist, FlightSafety Displays, Austin, TX

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Discussion Outline• History of Large Glass & Film

Cross-cockpit Mirrors• Glass versus Film Mirror

Characteristics• Mirror Shape• Localized radii deviations• Edge Roll Off• Training Tasks Sensitive to

Mirror Distortions

• Field of view• Impact Durability• Mirror Trim Cuts• Cleaning and Maintenance• Weight and footprint • Mirror Seams• Summary

SIM UniversityOctober 23, 20123

Large cross-cockpit collimated mirror history


Ad from ICAO Bulletin, May 1987Early 80’s: Rediffusion WIDE Film Mirror, Singer Link Miles AWARDS glass mirror (3 overlapping segments), McDonnell Douglas Multiview filmLate 80’s: Acrylic and other rigid mirror development efforts (Singer Link, CAE, Evans & Sutherland and Rediffusion), SEOS film mirror developmentMid 90’s: Pilkington Aerospace glass mirror development (C-130, F-18, Blackhawk)2001: Glass Mountain Optics (GMO) acrylic mirror for containerized CH-472007: GMO uses glass mirrors for CH-472008: GMO produces 7 segment, 45° x 300° FOV glass mirror system for Rockwell-Collins E-2D2012: FSI-Displays delivers first motion-based 60° x 220° glass system for FSI S-76D2013: FSI-D to deliver first motion-based 60° x 290° glass system for USCG HC-144

Optical design relies on ideal mirror shape


Mirror Shape Creation


Glass: • ½” thick substrate• Ground, polished and coated• Radius tolerance = 0.5% of radius• Mirrors produced in radius-matched sets (within

0.5% of each other)• “Blur circle” = 1” diameter or less

Mylar (shown before vacuum): • Aluminized Polyester Film• Shaped by stretching over a hollow mirror cell with

film clamped or taped around edges and applying vacuum.

• Tension in the mirror film is higher vertically than horizontally

• Horizontal tension is higher in center than along the top/bottom

Results of Non-Spherical Film Shape


FedEx Presentation “Accommodating an Aircraft Head Up Display in a Wide type Visual Display System” from FSEMC 2008 showed erratic glideslope as a result of Vertical Compression

White Grid shows geometry displayed to pilot; Red dots show true geometry

Localized Radius Deviations in Mylar Mirrors


Localized Blur Circle Deviations in film mirrors can be caused by: • Polyester film not of uniform

thickness throughout the mirror• Aluminized mirror coating is not of

uniform thickness• Film not attached to the edges of

the mirror cell in uniform tension

Results of localized deviations:• Image “swim” due to zonal image magnification changes• Star field accelerations; more noticeable in pilot’s peripheral vision

Image Roll Off around edges of Mylar Mirror


Mylar/film mirror images are prone to edge roll-off at the top, bottom and sides, distorting the image. Results:•Ground rush from image acceleration results in hard landings.•Bent runway edges and lines make judging height difficult, resulting in overshooting the touch down point.•Top edge distortions make air refueling challenging since tanker references are altered.•“S”-shaped horizon detracts from scene realism.

Glass Mirrors do not suffer edge distortion


Glass mirror image is undistorted out to mirror edge, and retains spherical shape across entire image.

Glass Mirror Systems Horizontal FOV is not limited


45° x 300° FOV glass system with 7 mirror segments.Glass mirror systems can have as many segments as needed to meet horizontal FOV.

Mylar Limited by 145”W Material Width Availability


Film mirror FOV is limited by polyester film width maximum of 145”. FOVs beyond 60° x ~210° require “splicing” additional Mylar.

Glass Mirror Durability (with proper backing)


Test of Phillips screwdriver drop on uncoated glass mirror (VIDEO)

Mirror impact testing

result, 4’ drop

Glass Mirror Custom mirror cuts


Forward and quarter mirrors trimmed for cockpit nose clearance

Multiple mirrors trimmed to expand FOV of collimated display beyond 60º

using real image chin and side displays

Glass Mirror Cleaning and Maintenance


Oily residue spread on surface of spherical glass mirror

After cleaning, the mirror was restored to its original condition with no damage to the mirror surface

Glass Mirror Weight and Footprint


220°H x 60°V Glass system on electric motion actuators during FAA acceptance testing at FlightSafety facility (VIDEO)

Glass Mirror Seams


Customer video of 300°H x 45°V FOV E-2D fixed base flight simulator consisting of 7 glass mirror segments

Glass Mirror Seams


• When viewing seams from 2 eyes, a different part of the scene will be obscured for each eye, so no information will be lost.

• Seam width is ~0.06”, or ~2 arc-minutes from PEP, which is less than half the pixel resolution of typical commercial flight simulator displays.

• These seams are closer to the pilot than the collimated scene being displayed and so are not in focus during flight training (“bug on the windscreen” phenomena)

Summary of Glass versus Mylar Characteristics


Characteristic AdvantageSpherical shape & lack of distortion Glass

Wide Field of View Glass

Impact Durability Glass

Trim Cuts Glass

Cleaning Glass

Display Weight Mylar

Seams Mylar

“Bonus Question” – why use 11’R vs 10’R Mirrors?


BP Screen Obscuration: What happens when you expand a ±20º VFOV 10’R Mirror system?

Option A: Enlarging BP Screen to Cover -40º obscures uplook

Option B: An 11’R Mirror system allows the BP Screen to be further up & back, reducing obscuration

Actual FOV from 24” offset Pilot Eye Point


From Center DEP, uplook = 15.47°;

From 24” PEP, uplook = 19.21°

Thank you.Questions?

SIM University 2012

SIM University 2012 - Christie · SIM University 2012 Glass Mirror Technology that is Reliable,...

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