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[MogulTx]

Gene,

What is the approximate screen radius you chose to work with? It looks pretty short. I have some experience in collimation and would be curious about the primary and the seconday radii (the projection screen).

How did you get involved in this? Will you use it for entertainment? Is it a real budget hog?

Let me know. I am working on a single channel system that will be 30+ degrees high and nearly 60 degrees wide on a 37" radius. ( Too short to use as a cross cockpit. Must be a single eyepoint only.) I am not using my bot for much of it! My mirror will be a solid mirror. And if you ever had a need, I MIGHT be able to scrounge you up a solid mirror... if I know the parameters.

Best Regards,

Monty

[geneb]

Monty, the mirror has a radius of 4 feet and the screen is about 2 feet. The size was limited by the Mylar we could find. A 54" wide roll is just wide enough to cover the conic section that the mirror framework defines. We found out recently that you can purchase really wide rolls from the likes of CAE, Rockwell-Collins, etc., but you're looking at $5k for a roll.

With the size of mirror we built, we can do cross-cockpit for "typical" GA types like the Cessna 172 or Beechcraft Bonanza. We're looking into the possibility of building something along the lines of an Embraer of some type as well. (I'm also going to build a single-seat fighter type and a single-seat car rig for Need for Speed:Shift)

I've been deep into home-built flight simulators since about 1997 or so. It's gone wildly out of control since then. This project started when I wanted to develop a better display system for the smaller cockpit design I'd done. I had built the prototype framework, but was chasing down a blind alley. I was going to use "gores" of material to give myself a direct spherical section display screen. The collimated display came about when Wayne Ledzian contacted me via the Mycockpit.org forums. He knew the math that had to be conquered in order to pull this off. It was pure accident that the prototype framework I built just happened to be the right dimensions - three of them put together build the 8' max diameter the Mylar can cover.

Anyway, between the two of us we managed to get enough cats running in the same direction to pull off the prototype mirror. This was a pretty big deal too - it had never been done by hobbyists before. Not only that, it was considered impossible due to the cost/complexity of it. The bad news is that we had to use a patented feature in order to properly form the mirror. We're going to try to obtain a non-commercial license for it so we can publish plans so folks can build this themselves. Without that, we'll only be able to publish so much and then go, "look at patent so-and-so and figure that bit out yourself".

The only real complexity comes with the math - that's pretty well understood and Wayne has built this awesome spreadsheet tool that spits out the magic numbers for you.

The prototype mirror used 2mil Mylar, the full curve mirror uses 1mil Mylar. Wayne scored a 50' roll (54" wide) from a local vendor for about $40.

I've probably got about $500 in raw material for this project and not all of that was spent at one time. In the wide scheme of things it's actually a pretty in-expensive project to build. Well as long as you don't factor in the cost of the 'bot.

With a solid mirror, are you going for a beam-splitter type collimation system?

g.

[myxpykalix]

"The prototype mirror used 2mil Mylar, the full curve mirror uses 1mil Mylar. Wayne scored a 50' roll (54" wide) from a local vendor for about $40."

Gene,
Where is this local vendor? The prices i've seen were higher then that?
I am trying to make a solar water heater and need some mylar. I want to make a big curved trough with this mylar in the back, what in your opinion is the best thickness? I know you use 1,2 mil but you need it to form to your curve off and on.

[geneb]

Jack, the vendor is http://www.mirrorsheeting.com/ and they're local to us so we don't have to pay shipping. I was incorrect on the price though - the 50' 1mil is $31.

I would recommend the 2 mil or thicker. 1 mil is VERY delicate. It won't tear that easily, but it's very easy to mar the mirror coating.

g.

[myxpykalix]

thanks gene