Pmerems

Pmerems

Well Known Member
Advertiser
Fellow builders,

I am in the process of laying out my RV-7A instrument panel an I want to get some input on 2 1/4" instruments. I am planning on using a Dynon D-180 EIFIS/engine monitor and mounting it directly in front of the left seat. In order to do this, I may have to use 2 1/4 backup instruments instead of the standard 3 1/8". I plan on having airspeed, altimeter, tach, as backup. My eyes aren't the best and I will be getting bifocals soon and I am a bit concerned that it maybe hard to read the smaller instruments.

Does anyone have experience with these smaller instruments in their panels.

P.Merems
 
2 1/4 Instruments

Paul, I am 6'4" (tall enough to sit way back from the panel), am correctable to 20/20 and at 61 yo I need bifocals (I chose to use progressive lenses which some say are harder to use than bifocals) and I have 2 1/4" instruments below my EFIS. I have the TruTrak Pictorial Pilot auto pilot, and an ASI and ALT. All are the 2 1/4" instruments. The ASI and ALT are "Winter" (sailplane) instruments made in Germany which are expensive but very nice quality.

The answer for me is that 2 1/4" are very easily readable. The sailplane folks live on this stuff and I am willing to bet many of them are not as visually acute as you or I. ;) Essentially if you can read this message sitting about 3' away from the computer monitor you will be able to see the 2 1/4" instrument well enough to use it as effectively as the 3 1/8" instruments.

I would not hesitate to use the smaller instruments. They make a neat panel and obviated the need for the knee knocking sub panel. :)
 
Just a note about progressive lens. I was having a little trouble reading the instruments, maps, and computer screens. Typical old age eye sight problems. I used bifocals for a couple of years but hated them. I could read a book great but the panel was too far away for the bifocals to work well. The computer screen also was not at the correct distance. I changed to progressive lens and now it doesn't matter what distance the object is that I'm trying to read. The more you raise your head the more magnification you get. The movement is very subtle and after a few days you will not even be aware of moving your head to focus. I also got the self darkening lenses but was disappointed to find they won't turn dark in the car. You still need some form of sunglasses when It's bright outside if your behind a windshield that blocks UV rays. Bottom line is the progressive lenses were the best solution next to laser surgery for my ageing eyes.
 
I've been wearing progressive lenses for quite a few years now and I love them. I did find that it was harder to get used to them flying, but once I did I like them better than bifocals. Just as a matter of record, I tried the "Varilux" brand of lenses and found them more difficult to use for some reason. I have a 2 1/4" tach and it is no problem to read. Most all my instruments in the rear seat of my bi-plane will be 2 1/4" because of panel space, (or rather lack of it).
Mel...DAR
 
The bold, no-doubt-about-it analog gauges won't give you a problem; the tiny characters and markings on the Dynon can be a challenge.

Consider purpose-made glasses. I wear bifocals with the near vision focus between 24 and 30 inches, and the upper dividing line is set much higher than typical so you don't have to crank your head back to see almost straight ahead. They're great for instrument panel distances, computer monitors, handgun front sights, etc. Think about it, and you'll likely find that most everything "near" in your daily activities and flying is a lot farther from your face than the standard reading distance of 18". I've tried progressives before, and nothing ever seemed in focus. Fields were way to narrow and I was constantly aiming my head. Must have looked like a bobble-head on the rear deck.

John Siebold
 
I don't know myself of course

You will not have any trouble with the analog gauges that instantly tell you what you need to know without an interpret the configuration of the display step in the process. What I'm told is not fun, is reading the small print at night on Jep charts that are now in mixed formats. Some say that tri-focals with the bottom section set for your specific seated "eye to thigh" distance; the mid-range set for the distance from your eye when you are seated in your airplane to it's instrument panel directly ahead of you; and the distance set for whatever they set the distance vision for normally, works well. Richard Collins had a writeup on this several years ago. What ever works - but the smaller gauges will not be a problem. I use some that are smaller in my panel. Photo below - notice the variable red/white & spot/flood light assembly on the left longeron just forward of the roll bar. I also have three little "eyeball" lights in little homemade aluminum boxes under the glareshield and most of the instruments are lighted. I did use a post light on the turn coordinator before I replaced it with a TruTrak Pictorial Pilot and it worked very well. In the space to the left of the E.I. Tach above the "six pack" I added the TruTrak Altrak switch/anunciator and below that the high/low intensity toggle switch.

Bob Axsom

dvc000151iy.jpg
 
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I know what you mean about the small focus area with progressive lenses. I am on my third pair and the technology gets better all the time. The field of view is much larger than it was a few years ago. I don't even notice moving my head now.
 
progressive lenses

not all progressives are created equal. my opthamologist started me on progressives at the first indication of the need for bifocals (age 40). i adapted to them fairly quickly, and enjoyed the ability to refocus for different distances by moving my head.

by the time i needed to update my prescription, we had moved to a new city and i needed a new eye-doctor. my company had some limited vision insurance plan, so i tried to save money and went to one of the providers listed. (it was an optical department of a major department store.) i got the progressives, and couldn't see the monitor at work or the instrument panel very well. so i called the old opthamologist and asked what "brand" of progressives she had provided and she told me. i called around until i found an optometrist that could get that lense. (actually, it was the first one i called -- closest to my house. i figured the discount wasn't worth squat if i couldn't see.)

the optometrist was very accommodating, and brought out a 10-12 page booklet comparing the different progressives (with about a dozen lenses per page). the "new" progressives i had been sold had a 9mm vertical distance between the far vision focal center and the near vision focal center. the brand originally sold to me by the opthamologist in the other city had a 20mm distance between the distant and near focal points. (obviously you can't get these lenses in the new "stylish" narrow frames.) i had become accustomed to using the "intermediate correction" area between the distant and near portions for, well, intermediate distances. with the narrower spread, i was having much more difficulty in "fine-tuning" the prescription. i immediately ordered a pair of the original brand, and have been using them ever since. in case you are wondering, the lenses i use are American Optical Omnivision Plus. i have no connection with the company other than as a satisfied customer.

another interesting thing i learned is that progressives (most of them, anyway,) have a "watermark" on the lense. it is extremely difficult to see, even when you know it is there -- good thing, too, or it would be interfering with your vision. the watermark is located (at least on my lenses) about 3/4 of the way up from the bottom of the lense, close to the pince-nez. mine read "AOB" (from the front).

i did finally have to break down and get a single-correction pair (focused to 28 inches) for reading music off the stand while playing french horn. with the horn resting on my knee and the alignment of my embouchure to the mouthpiece, i didn't have the freedom of head-movement necessary to focus. not a problem playing trumpet.

john
 
lenses

If found I tripped over my feet with progressive lenses (they were older technology.... :) )

My last pair of glasses I oredered as tri-focals, and found that having the 'line' visible made their use easy.

They are great for flying and driving... with the middle bit just right for the dashboard/panel, and still allowing map reading with the lower portion.

I though the middle bit was a fancy calculation, but apparently, it's just the mid-point between the main and reading prescriptions....

However... it does work for my eyeballs.... :)

gil in Tucson (but presently in Liverpool, England....)
 
Which lenses for flying

I have worn progressive's in the past and find them excellent for general use. The good thing about them is that you can fine tune on an object, no matter what distance, just by moving your head up and down. The downside to this is looking at something for an extended period of time, such as an instrument panel or computer screen, which can lead to a stiff neck, especially for those of us who may be slightly over the hill.

However, for flying, especially IFR, you are better off if you can minimize head movement when scanning the panel, charts, etc. For this you need a wide field of view, not available with progressives.

One problem is that most tri-focals have a narrow intermediate lens which will not cover the full height of the panel. I hunted for the right tri-focals that would do the panel, charts, and outside. It turns out that you can get tri's with an intermediate lens about 14mm high. That gives perfect coverage for the panel. You won't find them at Lenscrafters or other cut-rate optometrists.

Here's what they look like. They work great for all my flying needs and they work well for building an RV too.

p3120039large1fo.jpg
 
Bifocals have been a problem for me in "spam cans", so when I got my progressives I immediately checked things out by flying "the canoe". My instrument panel is the perfect distance to just move my eyes without moving my head to focus on the instruments. On my last visit to the eye doctor, I found that they can vary the progression on the lenses. It seems to me that with a little measuring, progressives could be fine tuned to the distance of your instrument panel.

Derrell
7A Finish
 
Derrell said:
Bifocals have been a problem for me in "spam cans", so when I got my progressives I immediately checked things out by flying "the canoe". My instrument panel is the perfect distance to just move my eyes without moving my head to focus on the instruments. On my last visit to the eye doctor, I found that they can vary the progression on the lenses. It seems to me that with a little measuring, progressives could be fine tuned to the distance of your instrument panel.

Derrell
7A Finish
Click to expand...

Maybe it's time for me to check out a new set of progressives.
 
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