2 Place Collimated Display

[geneb]

I started working on the new collimated display design yesterday after our resident Mathgician worked his magic. (*waves at Wayne*)

This first new project will fit cockpits that are Cessna 182 sized. It should also work out for small bizjets like _maybe_ the Lear 45 or some of the smaller Embraers.

That being said, this thing is NOT small. The 180 degree screen design is 86.444 inches wide (that's about 7ft 1/4in). The mirror will have a radius of 72 inches and will take up more space than that as the sphere radius is defined inside the framework. Once I get the rest of the components completed, I'll be able to tell you how much ceiling height you'll need.

Here's two renders of what the screen components look like. There are three primary components to the screen - an upper frame, a lower frame and and upper frame spreader bar. The shape is defined by 30 "blades" that will fit into the upper and lower frames. This build will go just like the last one did with respect to the screen.

screen-model-1.jpg
screen-model-2.jpg

I don't know yet how much this will cost. I do know that we'll offer both CAD drawings on CD as well as a "short" kit that will consist ONLY of parts that really should be CNC cut. You'll be on your own for the rest of the materials, fasteners and Mylar - we'll point you to our vendor so you can buy the film directly from them. The part kits will be shipped in crates made from 2x4s and 1/4" OSB. The material used will be 18mm and 12mm (essentially 3/4" and 1/2") Russian Birch.

If you don't want to worry about shipping & crating charges, the CD will include all the necessary files to hand off to a local fabber - they can be found at http://www.100kgarages.com.

Wayne tells me the 737 mirror will be a bit over 15ft in diameter, so if you guys with the big jet habit REALLY want a collimated display, you'd better hope you've got room for it. I would recommend consulting a good engineer before you start cutting rafters though. *laughs*

I'll update this thread as progress happens.

g.

[Mike.Powell]

Sweet! Anything worth doing is worth doing to excess!

Looking forward to it, Gene.

[fsaviator]

Wayne tells me the 737 mirror will be a bit over 15ft in diameter, so if you guys with the big jet habit REALLY want a collimated display, you'd better hope you've got room for it. I would recommend consulting a good engineer before you start cutting rafters though. *laughs*
g.

So what you're telling me, Gene, is that as soon as I get to Germany next month, I should be shopping for a house with a room at least 15' wide? Check!

[Efe Cem Elci]

Sign me up for the CD Gene...

[Tom_G_2010]

Ditto!!!! CD for sure. And, depending on the price point the pre-fab may be of interest.

I believe I've got the space for the radius mentioned, but the height may be an issue so I'll be watching closely to see what that turns out to be. I guess I could always try to snag some warehouse space from the family business...

[geneb]

Thanks all!

The 15' diameter is for the mirror sphere _only_. The framework will add 24" or so (at least) to each side.

One of the design changes I'm making for the new mirror chassis will be a better looking back to the assembly. The back will be made of a pair of 1/8" hardboard panels that are laminated into a conic shape on a jig.
This design change will do a few things:

1. It will remove the need for a special grid support structure to prevent the back from deforming under vacuum.
2. It will greatly reduce the interior air volume of the mirror. The airspace on commercial displays is very small - typically there is very little space between the back surface of the mirror and the front surface of the vacuum plenum.
3. It will reduce the width of the mirror chassis, but not by much.

The conic back sections will be probably the trickiest parts of the whole project to build. The two parts that make up the lamination will be different sizes to account for the k-factor when you bend them in order to make the edges line up correctly. Forming the sections will require a two part jig. The bottom will be a "positive" shape and the top will be a "negative" shape. The 2 1/8" hardboard sheets will be clamped between these jigs in order to form the sheets into a conic section that will retain it's shape when the glue dries. You'll be able to make the jig out of 7/16" OSB which is a pretty cheap material. You're only going to use it three times, so it doesn't make sense to use expensive plywood for it.

g.

[castle]

Hi Gene,

Is that 24 inches x 2 = 4 feet added to the 15 foot diameter". Seems like that would create a rather large volume? Also what is the diameter of the mirror at the bottom? 15' x cos( 50 degrees ) = 9.64' ? Ceiling height is 12' don't think that will be a problem and length of the space is 24'; however depth (width) of the stall is about 12.5 feet. That might be a little tight, but doable.

Regards
Jack

[geneb]

Jack, remember that the diameter of the mirror is as measured at the film itself. That doesn't include any structure to support it. My 24" addition to each side was simply a guess based on what I've got now. Also, the mirror is only 40 degrees high (0 at the top, down to 40), not 50.

--edit--
After thinking about it a little bit more, the "extension" past the mirror diameter will more than likely be under 8". I simply got my top & bottom dimensions flipped around.
-------
I've been catching up on house maintenance tasks this week, so no new work has been done. (I'm about six months behind THAT too. *sigh*)

g.

[castle]

Having just moved I know the feeling, the "honey-do" list keeps growing while a lot of the sim parts are still in boxes

Trying to visualize ( mirror/cockpit positioning ) the layout and tend to think in terms of two numbers; the screen diameter at the equator and at the southern edge of the FOV. Structure behind the mirror at the equator sets the total system size and the bottom number plus structure forward determines how much cockpit structure clearance exists when unit is positioned for the correct eyepoint(s).

Is the 15' mirror size based on the footprint of many of the shell plans available for the 737?
Might it be possible to use a smaller mirror? Reduce amount of materials required as well as the space. Or are we at the minimum acceptable limit?

Jack

[geneb]

As far as I know, the 15' (approximate!) diameter is based on a real 737 flight deck section.

The size of the mirror is dictated primarily by the size of the simulator cab.

g.