From: "Marvin Kaye" <marv@lancaironline.net>
Subject: Re: [LML] Re: Night vision goggles
To: lml
Date: Wed, 14 Feb 2007 17:30:18 -0500
Message-ID: <web-1838248@logan.com>
In-Reply-To: <7.0.1.0.0.20070214161119.0426c560@sc.rr.com>
References: <list-1838044@logan.com>
 <7.0.1.0.0.20070214161119.0426c560@sc.rr.com>
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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