[simpits-tech] So I've got this huge thing in my garage now.....

[Matt Bailey]

Thanks guys, I may just do that. I assume you need vertical and
horizontal FOV, height, and diameter?

I am not sure which way I am going with this yet......there are several
options. The original setup is almost identical to Gene's, with one key
difference. On Gene's rig, the projectors are in front of the cockpit,
and use direct projection onto the front of the collimator. On the big
sims (on this one, at least), three CRT projectors (of highly
specialized design) are mounted behind/inside this big ol' collimator,
and shoot through it. There are two layers to this collimator: the
inside layer is a smooth, clear piece with a bit of optics going on (I
believe it has a moderate Fresnel effect), and the outer layer is
frosted. This makes the projected image show up on the frosted layer,
after passing through the inner lens. From there it works exactly like
Gene's setup...a frame in front of the cockpit has reflective Mylar
which is pulled with a vacuum, and reflects the image that's on the
collimator.

I have never really considered Gene's setup as a viable option for me,
because of concern that I may lack the skills and tools to make a frame
and collimator that are accurate enough to make everything look right.
With my acquisition here, however, a significant piece of the puzzle is
done for me. But this thing is already 12ft wide by itself.....the
screen would be huge! I do think that having the projectors inside this
collimator has allowed the big sim guys to get by with a smaller Mylar
screen than otherwise possible (since no space is required in front of
the collimator for the projector beams).

I have more or less ruled out using the collimator with the
projectors behind it, though I am going to test that out. Aside from my
projectors probably not being as bright as what the big sims use, one
of the reasons I was able to acquire this thing is because the two
layers are starting to delaminate....the glue inside is drying up,
which causes the screen to lose a LOT of light passing through it (or so
I'm told..it's not noticeable as it sits right now). If I do front
projection instead (and paint the outside of the collimator), I can
preserve almost all the light from the projector. This setup would
essentially be exactly what Gene is doing, just on a larger scale.

If I don't go with a Gene-Screen, here are a couple other options:

1: I could use the collimator itself as the screen, and mount it in
front of my sim, with the projectors above the sim, projecting directly
onto the collimator. Again, I would need to paint the collimator with
some reflective paint.

2: A second option is a variation on the above option. I could still use
the collimator as the main screen, but I would mount the projectors in
front of the collimator, taking advantage of the frosted finish to make
the image project onto the screen. This is basically the reverse of how
it was used originally. Again, the delamination and light loss that
this collimator supposedly suffers would be a factor. It would also
mean the entire setup would take up more room...BUT, the BIG advantage
here is that I would have no clearance considerations between the
projectors and the cockpit (I could put the screen as close or as far
as I want from my cockpit). I also might get some sort of beneficial
Fresnel effect from the inside layer.

Like I said, this thing is 12ft wide, so I could use it as the main
screen. I have sat down in front of it several times and looked around
at the inside surface....I think it's big enough to fill the view of any
standard business jet if I mount it correctly to its geometry (IOW, any
given section of the screen would be 6ft from the pilot's viewpoint).
Using it as the screen itself is very appealing from a simplicity
standpoint, and from the standpoint of making the sim mobile. Right now
my sim consists of the cockpit itself (which is on wheels, and can
easily be moved by two people), a stand with the projector on it, and
another stand with a flat projection screen. I could mount this thing
on a wheeled base that rolls up to the sim, and mount three projectors
on another base to go behind/above the sim. Options, options!

One thing is for sure...I am about to pull my projector down from its
lofty perch above my sim and have some fun with this big ol'
collimator. :)

Matt

On Fri, 2 Aug 2013 15:41:18 +0000 (UTC)
wledzian1 at comcast.net wrote:

> Yep - if you ever want mirror specs to match, I can run the numbers. 
> 
> ----- Original Message -----
> From: "geneb" <geneb at deltasoft.com> 
> To: "Simulator Cockpit Builder's List" <simpits-tech at simpits.org> 
> Sent: Thursday, August 1, 2013 8:15:30 PM 
> Subject: Re: [simpits-tech] So I've got this huge thing in my garage
> now..... 
> 
> On Thu, 1 Aug 2013, Matt Bailey wrote: 
> 
> > It is exactly what it looks like....this is the back-projection 
> > collimation screen from a level D commercial flight simulator. :)
> > Now what to do with it......hey Gene, I think I have the start of a 
> > jumbo-sized version of your collimated display system. :) 
> > 
> Take very, very good care of that thing Matt. If you can figure out
> the specs on the shape, Wayne could likely give you the numbers
> needed to build a matching mirror cell for it. 
> 
> g. 
> 
>