Night Vision Goggles (NVG discussions merged)
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Instrument viewing using NVGs
Hello all,
I'm an NVIS compatible instrument conceptor and I while I was giving a NVIS training I received a question from a military test pilot to which I didn't have a good answer. So I will submit it to this forum.
This is what the pilot does:
1) When flying with NVGs his instruments are dimmed to a bare minimum to be completly NVIS compatible.
2) Since the NVGs where set to focus at infinity (to see clearly outside) he reads the instruments by looking under the goggles (instruments are out of focus with the goggles) but because his eyes are not dark adapted (gen IV are bright!) he needs to increase the light levels of the instrument.
3) When going back to looking through the googles he needs to dim the instrument lights again
His question:
Why do I have to go throught all these steps? Is there a more efficient way?
Thank you
I'm an NVIS compatible instrument conceptor and I while I was giving a NVIS training I received a question from a military test pilot to which I didn't have a good answer. So I will submit it to this forum.
This is what the pilot does:
1) When flying with NVGs his instruments are dimmed to a bare minimum to be completly NVIS compatible.
2) Since the NVGs where set to focus at infinity (to see clearly outside) he reads the instruments by looking under the goggles (instruments are out of focus with the goggles) but because his eyes are not dark adapted (gen IV are bright!) he needs to increase the light levels of the instrument.
3) When going back to looking through the googles he needs to dim the instrument lights again
His question:
Why do I have to go throught all these steps? Is there a more efficient way?
Thank you
Night Vision Goggles (NVG discussions merged)
Hi lupin861,
Two sollutions possible.
First, get the aircraft propperly fitted with nvg compatible instruments and lightning, so that he can turn the instrument lights up - but the lights may be seen by enemy forces.
Second, get nvgoogles, in which you can display information from the instruments, like in a HUD
Greetings Flying Bull
Two sollutions possible.
First, get the aircraft propperly fitted with nvg compatible instruments and lightning, so that he can turn the instrument lights up - but the lights may be seen by enemy forces.
Second, get nvgoogles, in which you can display information from the instruments, like in a HUD
Greetings Flying Bull
I suspect your inquisitor was from an early "NVIS" period.
Modern NVD compatible cockpits don't have this problem.
PS: What is an: "NVIS compatible instrument conceptor"? Sounds sexy!
Modern NVD compatible cockpits don't have this problem.
PS: What is an: "NVIS compatible instrument conceptor"? Sounds sexy!
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It's a nice job 
I design cockpit instruments, chosing material/ circuit card/ fitlering material etc. When they go into military aircraft/ rotorwing I make them NVIS compliant. (the amounth of light in the IR is limited)
We can assume the mission is covert so the lights need to be dimmed.
When I look at my instruments with a type I gen III, I need to readjust the focus to read the legends. I had always though that was how pilot did it also.
A holographic NVG would do the trick. I'm not aware of any...
I design cockpit instruments, chosing material/ circuit card/ fitlering material etc. When they go into military aircraft/ rotorwing I make them NVIS compliant. (the amounth of light in the IR is limited)
We can assume the mission is covert so the lights need to be dimmed.
When I look at my instruments with a type I gen III, I need to readjust the focus to read the legends. I had always though that was how pilot did it also.
A holographic NVG would do the trick. I'm not aware of any...
We can assume the mission is covert so the lights need to be dimmed.
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MightyGem,
You are right when the element of surprise is needed. However with NVS equipped toerags kicking around, all they want is to pinpoint your position a little more accurately to fire some headache pills your way.
Those lovely wander lights at the back of the cockpit make great illumination for the glasshouse esk cockpit, even at surprising heights!
I for one dimmed lights down to the absolute minimum for any trooping/landings, the wander lights in my aircraft were luckily made obsolete by an upgrade allowing direct and more subdued light to be shone on the instruments. I was equally concerned about excessive lighting above the threat band after being shot at fairly close a couple of times while working.
As for using goggles in a non equipped NVG equipped aircraft = highly sub optimal for anything other than basic transit flying. I know of one incident recently where the crew became disorientated on goggles, did not have a full NVD cockpit.......and the situation was made unduly stressful (and potentially dangerous) by the need to revert back and forth (this is a two crew cockpit as well!)
You are right when the element of surprise is needed. However with NVS equipped toerags kicking around, all they want is to pinpoint your position a little more accurately to fire some headache pills your way.
Those lovely wander lights at the back of the cockpit make great illumination for the glasshouse esk cockpit, even at surprising heights!
I for one dimmed lights down to the absolute minimum for any trooping/landings, the wander lights in my aircraft were luckily made obsolete by an upgrade allowing direct and more subdued light to be shone on the instruments. I was equally concerned about excessive lighting above the threat band after being shot at fairly close a couple of times while working.
As for using goggles in a non equipped NVG equipped aircraft = highly sub optimal for anything other than basic transit flying. I know of one incident recently where the crew became disorientated on goggles, did not have a full NVD cockpit.......and the situation was made unduly stressful (and potentially dangerous) by the need to revert back and forth (this is a two crew cockpit as well!)
Lupin - since you are not talking about a combat environment then the ideal is NVG compatible lighting which should still be dimmable to reduce reflections in the cockpit transparencies.
We regularly fly on mixtures of instruments/NVD/white light and looking under the goggles is often a technique needed to identify the colours of lights (blue flashing ones for example), as well as conducting your instrument scan.
However, it is still important to reduce the light levels in the cockpit as your eyes acclimatise to the dark - wearing NVD does not ruin your normal night vision since your rods adapt but your cones are affected such that normal lights look brownish after a while.
One important issue is not to wear your goggles too close to your eyes because a. you can cause eyestrain trying to focus on something too close and b. you can't look underneath the goggles easily.
As Flying Bull says, NVD with a flight instrument display superimposed on the goggle picture is one way forward but these installations are usually high-end military only - at the moment anyway.
One problem that is difficult to solve wearing NVD is selecting switches/circuit breakers etc that are in the roof panel since it requires such an extreme tilt of the head to look under the goggles that it is nigh on impossible - you are left with using muscle memory and your knowledge of the roof panel layout - or taking your goggles off.
Another problem is for glasses wearers, especially those who need to read maps or documents on NVD - the answer for me is to wear the goggles but focus them with my glasses on (only about 1.5 dioptre prescription) since I am just bringing the phosphor screen into focus it is a small adjustment. Then looking at the instruments under the goggles (but through my glasses) I have nearly perfect focus but looking down at the map I have excellent focus. As most of those of a certain age will know, it is low light that makes focussing on the printed page difficult.
We regularly fly on mixtures of instruments/NVD/white light and looking under the goggles is often a technique needed to identify the colours of lights (blue flashing ones for example), as well as conducting your instrument scan.
However, it is still important to reduce the light levels in the cockpit as your eyes acclimatise to the dark - wearing NVD does not ruin your normal night vision since your rods adapt but your cones are affected such that normal lights look brownish after a while.
One important issue is not to wear your goggles too close to your eyes because a. you can cause eyestrain trying to focus on something too close and b. you can't look underneath the goggles easily.
As Flying Bull says, NVD with a flight instrument display superimposed on the goggle picture is one way forward but these installations are usually high-end military only - at the moment anyway.
One problem that is difficult to solve wearing NVD is selecting switches/circuit breakers etc that are in the roof panel since it requires such an extreme tilt of the head to look under the goggles that it is nigh on impossible - you are left with using muscle memory and your knowledge of the roof panel layout - or taking your goggles off.
Another problem is for glasses wearers, especially those who need to read maps or documents on NVD - the answer for me is to wear the goggles but focus them with my glasses on (only about 1.5 dioptre prescription) since I am just bringing the phosphor screen into focus it is a small adjustment. Then looking at the instruments under the goggles (but through my glasses) I have nearly perfect focus but looking down at the map I have excellent focus. As most of those of a certain age will know, it is low light that makes focussing on the printed page difficult.
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Hi,
which Airframe does the MilitaryTest Pilot fly who asked?
The best and nowadays comon way is to use NVG compatible cockpit lights.
In my case I have the luck to fly an Airframe where I can change the lights from OFF/ON to NVG mode.
In the NVG mode you can see everything by looking under the goggle on your instruments and at the same time it doesn´t blind you by looking through the goggle.
Back in the BO-105 days there was no NVG mode available. Tapes where put on unnecessary lights/instruments.
For important instruments there where coloured plexiglas mounts to put over the instruments.
which Airframe does the MilitaryTest Pilot fly who asked?
The best and nowadays comon way is to use NVG compatible cockpit lights.
In my case I have the luck to fly an Airframe where I can change the lights from OFF/ON to NVG mode.
In the NVG mode you can see everything by looking under the goggle on your instruments and at the same time it doesn´t blind you by looking through the goggle.
Back in the BO-105 days there was no NVG mode available. Tapes where put on unnecessary lights/instruments.
For important instruments there where coloured plexiglas mounts to put over the instruments.
Last edited by Capt.Gonzo; 20th Dec 2012 at 15:31.
gen IV are bright!
if you are referring to NVGs, no such thing as gen. IV. since 2001, when that designation was withdrawn by NVESD. "Thinfilmed", "filmless", but still gen III.
Gen. IV is marketing department hype.
Arrakis
Marketing hype.
Without going into the details, I would say the cockpit NVD adaptation and the goggles were not matched.
Arrakis
2) Since the NVGs where set to focus at infinity (to see clearly outside) he reads the instruments by looking under the goggles (instruments are out of focus with the goggles) but because his eyes are not dark adapted (gen IV are bright!) he needs to increase the light levels of the instrument.
Arrakis
Last edited by ARRAKIS; 20th Dec 2012 at 19:28.
Those lovely wander lights at the back of the cockpit make great illumination for the glasshouse esk cockpit
However, I now fly NVG without having to use wander lights, all instrument lighting being internal, and NVG compatible, so not visible from outside the cockpit.
ARRAKIS - we have recently acquired Gen IV tubes and they are significantly better both in low light and in dealing with bright external lights (less haloing) - it's not just marketing hype.
Less Haloing is usually down to using a gated power supply - a mod to gen 3 tubes that the SF types have been using for years. Much better than the bog standard gen 3 tubes
ARRAKIS - we have recently acquired Gen IV tubes and they are significantly better both in low light and in dealing with bright external lights (less haloing) - it's not just marketing hype.
Of course, any company can use any naming, even claim selling gen. V (that's for XR-5 IITs), but it will be just marketing.
There is also question of IITs with a gated power supply, that will work even in dayligh, but that's another story.
You have - probably - what ITT is calling Pinnacle. Those are gen. III thinfilmed IITs.
There is now something new. Tubes based on 2 micron pore MCPs, giving around 70 degrees FOV, but the price that USMC had to pay for the first test samples was, well, quite high.
Arrakis
Interesting info ARRAAKIS, I don't really care what they are called but they do give a significantly better performance - we were told they were Gen IV but if they turn out to be Gen III filmless, thinfilm or whatever the US Army cares to classify them as, it matters little to the user.
it matters little to the user.
By the way [historical mode on], probably the best (in my humble opinion) night vision equipment during WW II was British made, called at the beginning R. G. Equipment, from the lighting red glass filters that were used, later changed to Tabby. It included, for example, infrared IFFs for aircrafts.
If anyone knows where to look for information about Tabby's operational use during WWII, please let me know.
[Historical mode off]
Back to the XXI century, and lupin's question no 2.
It looks like the lighting in the cockpit is affecting the goggles.
If I recall correctly the research results I have read years ago about NVG cockpit lighting adaptation, if the brightness difference between the goggles phosphor screen and the instruments lighting was too big (2 orders of magnitude), it was affecting the instruments reading. -> The instruments lighting was dimmed to avoid problems with the goggles.
The test were made on the artificial horizon, and the pilots over 35 y.o. needed a few (5-7) seconds to read the tested instrument. For younger pilots the problem was less visible, but still present. It's from memory, so the numbers given above may not be correct, but the effect was as described.
Imho, the situation, as described by lupin, should require a closer attention.
Merry Christmas all.
Arrakis
Last edited by ARRAKIS; 24th Dec 2012 at 09:16.
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ARRAKIS,
I have used the pinnacle tubes, very impressive. We knew them as pinnacle plus? Have you heard of those?
Low light, "red illume" level dust landings were significantly more comfortable!
Add DNVG, and you are laughing!
I have used the pinnacle tubes, very impressive. We knew them as pinnacle plus? Have you heard of those?
Low light, "red illume" level dust landings were significantly more comfortable!
Add DNVG, and you are laughing!