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Posted for "S. Reeves" <sreeves@sc.rr.com>:
Jerry,
Thanks for the great info. You raised some issues I hadn't
thought of. I had originally planned to kill all of the lighting in an
emergency, but I forgot about the focus range and reading the instruments. I
looked through a monacle (ITT Night Enforcer I believe...) and definitely see
how light sensitive they are. I guess the main problem would be dealing with
viewing the instruments, in which case I'm not sure how that would be done! I
had been thinking of something like this (or around the same price range):
http://www.opticsplus.net/NightVision/Goggles/ATNNVG7Gen22Free5xMagLensonselectmodels
Could anything be done about instrument viewing? Thanks for the input. I
did get a couple of the usual LML smartass replies, but they might think
differently if they have an engine fail if they fly at night, which I know
alot of them do. A thousand bucks is worth improving my odds.
Steve Reeves
Glasair 1FT 38SR
Based at CUB
>I did the initial test flights in a fighter at low level using NVGs back in
1980, and have been involved off and on in their development since then. They are certainly amazing devices which can greatly ease pilot workload at night. However there are snags, as ever.
There are essentially 2 types readily available, Gen 2 and Gen 3. Gen 2 work down to about 1/4 moonlight and have fairly wide frequency response. They are useless looking through any kind of glass, but plexiglas or other plastics have a much lower impact on performance. The cheaper ones are generally Gen 2, which are OK if you understand their limitations. Gen 3 are higher performance down to starlight, and work in the green part of the spectrum.
The main concerns are cockpit lighting, head mounting and training. You absolutely cannot use NVGs with red or white lighting, they are totally dazzled by even dim light reflections. What we did was fit the front lens of the NVGs with a red filter, then modify the cockpit lights to a specific narrow band green standard; we used EL strips, but you have to play with different lights and filters. Theater floodlight filter material is cheap and works well. Turning the cockpit lights out does not work, because the NVGs are focussed at infinity, and you cannot read the instruments through them.
Head mounting could be a problem, unless you wear a helmet. You can hold them, but it would be difficult in a high stress situation, especially in turbulence. They often come with some form of head mount, and you would have to work out how to adapt it for our purposes.
Finally they lack a degree of depth perception, and are of course monochromatic. Make sure that they lack magnification as well. for obvious reasons; there are a few that are not 1:1. You would need to practice using them in a safe environment beforehand, with a safety pilot on board. Having said all that, I would definitely want to have a set around if I had to do a forced landing at night. They would turn an impossible situation into a merely difficult one.
Jerry
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