Collimated display project update...

[geneb]

You guys are confusing copyright with patents.

There are fair use provisions in copyright and that's why building yourself a 737 flight deck is no big deal.  With fair use, you can create a copy for personal use without issue.

Copyright isn't something we're worried about - the setup we're building is 100% of our own design.  The problem comes where we're using a patented technique in the construction of the mirror.  There is no fair use for patents - while we can _technically_ build a patented device in order to understand how it works, it gets sticky when we provide information to others as to how THEY can build one for themselves.

This whole project will come out one of two ways.  We'll get the permission we need for a free non-commercial license and we can release the plans.  The other way, we don't get permission and we release what we can, point you at the patent we referenced and tell you to figure it out for yourselves.

Keep in mind all that needs to happen to wipe us both out is for them to just _file_ a suit.  That's just the way it is - we need to play as nice as we can with these folks. 

The chance of us actually getting permission is pretty small - but it's big enough to be worth asking.  Please don't rock the boat.

Watch this spiffy video instead:

http://www.youtube.com/watch?v=t7553ZkkPXY



g.

[geneb]

This update should cover the past couple of weeks worth of work...

The "spider" arms for the screen & projector support platform were cut out last weekend.

Here's what they looked like right after getting sanded & painted with shellac sanding sealer:



In order to strengthen the material joints in the screen support parts, we needed to cut a set of doublers.  Part of this was seeing if we could get the 'bot to do the countersinks for us.  I had a 3/8" 82 degree countersink that I could fit to the 1/4" collet on the 'bot.  Wayne created a file in VCarve that would have countersinks at various depths - turns out .210" is perfect for a #8 flat head screw:



Having the 'bot do all these is a LOT easier than me doing it with a microstop!



This is what the doubler parts looked like as they're being cut:



...and after being glued & screwed to the screen support panel:



After getting those in, we added the "spider" legs - you can see from the picture why I call them that:



Here's a picture of what it looked like after we got the top layer added.



Like most spiders, this one doesn't like being on its back...



Here's a long shot with the screen support resting on the mirror framework.



Just for the heck of it, Wayne clamped in the first screen section we ever built - this is actually a small slice of the full size screen you saw being assembled in the time-lapse video.



I figure I'll hang on to that ratty old thing - who knows, the Smithsonian might want it some day. *laughs*



This picture is pretty amusing.  Wayne is all, "Hurr!  This is SO cool!", while my friend Rob is all, "Hrmm.  I do believe we CAN take over the world with this!"

Please note the pink foam screen analog.   It's about the right size for a 19" display.

Here's a couple of shots with the screen installed:





I would have taken a wider angle shot, but I couldn't back up any further while it was in the location it was.  Stupid thing is so big you have to back WAY off to get it all in one frame!

During the week I'll be applying sealer to the screen frame components and the screen mounts so they can be painted.  With any luck we'll be able to get the foam inserts installed into the screen soon!

g.

[geneb]

Hehehehehhee.  You're welcome.

We've almost reached the point where thinking about how close we are to the first draw-down of the mirror makes us start to twitch and drool a little bit.

g.

[geneb]

Update for the work done on Saturday, 21May11:

The screen support "spider" is completed and painted:



The only remaining work that needs to be done is to have the projector mounts located & drilled.

We got the foam blocks cut for the screen.  That stack of material used to be four 96" x 24" sheets.  Wayne built a slick jig that allowed them to be bevel cut without getting your fingers too close to the saw blade.



The blocks shown above were hot-wire cut in a special jig that used spare ribs from the screen in order to get the shape perfect.

Look carefully at this picture:



Can you understand why I'd want to whack it with a crowbar as I went by?

Each mirror segment and the backs are sealed with a 1/32" rubber gasket to minimize the amount of air leaks in the system.



Applying the framework back panels...



The colors for the frame will be yellow for the "ear" boxes and peripherial framework and blue for the back panels.  Gotta keep with the whole Simpits/Link Trainer colors you know.

We also test-fit the new goggle-mask.





It's quite likely that when the mask is attached "for real" to the framework, the mylar for the mirror will follow shortly behind.  Right now we figure we're only one or two work days from performing the first draw-down of the mirror.

The screen was assembled and the first layer of filling compound was applied.



Once the sand/fill cycle is done and the shape is correct, I've got some Behr screen paint we're going to try with it.

Thanks for reading!


g.

[wledzian]

We didn't do any structural calculations; we simply observed the behavior of the prototype segment under vacuum, beefed it up where it flexed, and cut back where it appeared overdesigned.  The general concept should work OK when upsized, but may need additional ribbing to prevent oilcanning of the back-side sheeting.

Our biggest obstacle to size is the availability of wider mylar at reasonable prices.  You can go larger if you're willing to sacrifice on the horizontal FOV.

[wledzian]

The mylar we're using cost us a whopping $30 for 50 feet of the 56" stuff, so we're not all that worried about a popped mirror aside from the hassle of refitting it.  At $5k, I'd be a bit more concerned.  Also, there are some design aspects of the larger installations that I'm not fully schooled on yet, such as the effect of shifting the eyepoints significantly sideways and forward for a wide dual-pilot cockpit.

Regarding the construction, there are several details of our build that fall into the "because we can" category.  There aren't really any critical design features there that couldn't be built with careful use of 'normal' wood-shop tools.  The shopbot is wonderful in that it lets us build parts almost as fast as we can conceive them and draw them up, and it lets us incorporate features such as indexing tabs that help to speed up assembly without having to jig everything up.

If you do decide to go this route, I'd be willing to supply the critical optical geometry (after we get both of our displays up and running).

[Efe]

Gene what is the specs for the mylar you used for this? Thickness, model, etc.
Thanks.