Helmet-mounted displays

Cockpit, radar, helmet-mounted display, and other avionics
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popcorn

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Unread post29 Aug 2018, 12:30

Dumb question... Can:t DAS be used for night landings?
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Unread post29 Aug 2018, 13:19

How is the DAS viewed? Using the HMDS with GREEN GLOW was the problem. Flying the meatball from more than a nautical mile out is ideal for transitioning to 'just flying the meatball' in my opinion. However IMAGINING how things look with the GREEN GLOW in HMDS probably taxes me the most. Never used a HUD meself but saw a few BLACK NIGHTS!!!!!

DAS gives an overview - especially the horizon on a black night - so it orientates the pilot helping to prevent THE LEANS. However he needs the HMDS view with AoA indexer to see the MEATBALL & all WITHOUT THAT GREEN GLOW thingamajig.

THE LEANS = spatial disorientation, especially when there is no visible horizon. Flying into a BLACK HOLE with only a VERY BRIGHT IFLOLS and perhaps a few lights on the ship if you can see them at a distance can be daunting as there are no other cues about how things are progressing down that BLACK HOLE until perhaps things become clear closer in which may make corrections difficult especially if the LSO is a bit slack (probably not though) - he is ON THE BALLs of his feet! ready to SCREAM WAVEOFF WAVEOFF WAVEOFF or POWER POWER POWER, DON'T CLIMB! :mrgreen: Don't feel sorry for the LSO - he is standing on the freakin' deck already - the same deck you will stand on soon enough - you hope :drool: with OK Three wire.
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Unread post29 Aug 2018, 13:43

Spaz captured it, popcorn. In simple terms, green glow makes the ball harder or impossible to see. DAS all but obscures it; DAS is good for spatial and situational awareness at night in generally clear air mass conditions.

In microcosm, green glow is a bit like having your dashboard lights turned up too high in your car at night. It obscures the stuff you wanna see outside.
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Unread post29 Aug 2018, 13:54

Good explanations... Illuminating. :D
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Unread post29 Aug 2018, 16:18

The "Green Glow" issue is with the HMDS image projectors and will be the same regardless of what sensor is providing the display. It affects EODAS, EOTS, nose camera, helmet camera, or native "HUD" imagery equally.

We can simulate the issue for ourselves. If you have a non-OLED cellphone, tablet, or laptop you can turn it on and find a "black screen" that covers the whole screen. Now go into a dark room and look at your device. You will see the backlight bleeding through around the pixel edges. That is the "glow" in the "Green Glow"

https://www.pchardwarehelp.com/guides/b ... eeding.php
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Unread post29 Aug 2018, 22:27

Popcorn, Spud is correct. But, to clarify wrt your question re use of the DAS for night landings, the matter goes beyond 'green glow.'

Any additional image (beyond 'HUD' symbology) projected in/on the visor -- particularly from sensors that don't 'see' in the 'visible light' portion of the spectrum -- will obscure the Fresnel lens/ball/optical landing system. Even for imagers that 'see' in that part of the spectrum (e.g. like NVGs or a 'night camera'), precision will be reduced -- i.e. the position and movement of the ball relative to the datum will be degraded. The degree of precision necessary for CV approaches is higher due to the geometry and time segments of arrested landings. Additionally, there is the matter of parallax between the sensor and pilot design-eye that make use of those imagers impractical.
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Unread post29 Aug 2018, 22:39

Thanks - good to know those details - precision is everything during carrier approaches - details need to be seen clearly.
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Unread post29 Aug 2018, 22:48

Delay was also a big issue with EODAS/EOTS driven carrier landings. EODAS imagery has to go through a "stitching" engine that combines the 6 EODAS views into a single feed. EOTS goes through a similar but much less complex process of mostly image processing and angle syncing. These processes add some delay of the feed to the HMDS which is not critical when talking about an item that is thousands of feet away. However, that delay is dangerous when it comes to a carrier landing.

To address this, the program added 2 extra cameras that feed directly into the HMDS. There is no pre-processing of the feed outside of the imagers themselves. This ensures the smallest delay possible between the camera and the HMDS. One is on the "dashboard" where the HUD would normally be and the other is on the helmet above the visor. Think of these as the closest direct replacement of traditional NVGs that the has. Unlike traditional NVGs, they do not have to be lowered into place. The pilot only needs to flip a switch (physically or by voice command) to turn them on/off.

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Last edited by SpudmanWP on 29 Aug 2018, 23:20, edited 1 time in total.
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Unread post29 Aug 2018, 23:18

Good info guys...thanks.
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Unread post29 Aug 2018, 23:39

I've dug up photos of all three Generations of F-35 helmets to show has the helmet camera has gotton significantly later with each generation.

Gen 1

Image


Gen 2

Image


Gen 3

Image
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Unread post29 Aug 2018, 23:46

"Delay was also a big issue with EODAS/EOTS driven carrier landings."

Image latency was an issue for a time, but neither system was ever a part of the CVN recovery equation.

Huge (entirely misplaced) bru-ha-ha for a while over latency with all kinds of doom and gloom pronouncements about spatial 'd'. You-da thunk no one had ever flown at night with night vision devices before. :roll:
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Unread post30 Aug 2018, 00:25

quicksilver wrote:Image latency was an issue for a time, but neither system was ever a part of the CVN recovery equation.
Damn, now I can't remember where I picked that bit up.

Thanks for the clarification.
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Unread post30 Aug 2018, 01:47

Why 2nd Camera in front of pilot reason would be in this forum somewhere - perhaps this thread? As I recall the canopy bow got in the way when just the helmet camera was used during BOOM or probe/drogue night air refuelling. 2nd camera got rid of that problem. Meanwhile stitched JPG.
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Unread post30 Aug 2018, 02:30

Vaguely I recalled this old description of HMDS carrier approaches, old story but only on previous page 57 of this thread. Perhaps this 'how green is my glow' report is also on another contemporary thread? I'll check later....

viewtopic.php?f=62&t=16223&p=392169&hilit=Seck#p392169
Pilots to Test Fix for F-35 Helmet 'Green Glow' Problem
16 Aug 2016 Hope Hodge Seck

"...Adjustments that decrease the contrast of the Generation III helmet-mounted display should allow pilots of the F-35C to land on aircraft carriers without having their view obscured by the display's ambient light, said Tom Briggs, acting chief test engineer for the Navy....

..."You could describe it as looking through a dirty window," Briggs said. "It's not so bad on a really bright night. On a dark night it skewers outside light references for pilots. A pilot cannot pick up the lights on the carrier as well as he'd like to, he doesn't necessarily pick up non-lighted signals on the ship as he's taxiing around, he has a harder time picking out aircraft that are flying around."…

Christie [Capt. James Christie, commanding officer of Strike Fighter Squadron-101] said the decreased contrast setting is likely to help all pilots who operate in especially dark environments, without aid from the 'cultural light' of nearby cities. But on carriers out in the middle of the ocean, it was crucial. "I think we just kind of stomped our feet and said, ''we need to have this to be safe around the ship,'" he said....

...Briggs [Tom Briggs, acting chief test engineer for the Navy] said nighttime helmet tests were expected to kick off Aug. 20 [2016], during the darkest phase of the moon. "So we're going to go out on a really dark night and we're going to do our final evaluation on the green glow," he said. "And we think that that problem is solved." [NOPE adoodie]"

Source: https://www.military.com/defensetech/20 ... ow-problem

Dec 2016 "...“[green glow]make(s) it difficult for pilots to detect outside light sources and the cues they need to land their aircraft safely. While testers were hopeful at the time the problem was solved, Bogdan said officials are not yet satisfied. The symbology on the helmet, even when turned down as low as it can, is still a little too bright,” he said. “We want to turn down that symbology so that it’s not so bright that they can’t see through it to see the lights, [I think the reference is to IFLOLS lights etc.] but if you turn it down too much, then you start not being able to see the stuff you do want to see. We have an issue there, there’s no doubt.”" viewtopic.php?f=62&t=16223&p=358568&hilit=Seck#p358568
RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
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Unread post30 Aug 2018, 15:39

spazsinbad wrote:Why 2nd Camera in front of pilot
My thought would be in case the HMDS or helmet cam goes tango uniform, the dashboard feed can be displayed in the main tactical display.
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