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FlightGear Newsletter November 2010: Difference between revisions
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FlightGear Newsletter November 2010 (view source)
Revision as of 17:19, 30 November 2010
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=== Amateur Built Collimated Display === | === Amateur Built Collimated Display === | ||
Contributed by Gene Buckle | ''Contributed by Gene Buckle'' | ||
A couple of months ago, my friend Wayne | A couple of months ago, my friend Wayne and I embarked on the development of a fully functional collimated display system for our DIY flight simulators. A collimated display has been the holy grail of DIY cockpit builders because of the image it generates. Collimated displays are also known as "infinity" displays. It's described that way because the focus point to your eye becomes "infinity" when you're located at the right spot when viewing the mirror. The exact details of how they work are beyond this article, but you can learn more at [http://en.wikipedia.org/wiki/Full_flight_simulator Wikipedia]; see the section marked "Collimated Cross-Cockpit Displays". | ||
Building the display successfully is a pretty big deal. Up until we completed the proof-of-concept project, collimated displays were the sole domain of multi-million dollar flight simulators from the likes of CAE, FlightSafety and others. It was declared too complex and too costly by just about everyone that ever approached the problem. Fortunately for us, all the "experts" were wrong. Not only did we build a fully functional collimating display, but we did it with off the shelf materials and very, very little expenditure. Total material costs for the mirror and projection screen is under $100. | |||
The test mirror was built using an 8 foot diameter spherical shape. The framework itself describes a 60 degree wide by 40 degree high "slice" of that shape. The mirror itself is made of a 48" wide, 2mm thickness of Mylar sheet. In order to properly stretch the mirror, a set of "ears" had to be added to the framework. | |||
The test mirror was built using an 8 foot diameter spherical shape. | |||
This shows the frame prior to the mirror being glued into place: | This shows the frame prior to the mirror being glued into place: | ||
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[[File:mirror_frame.jpg|200px|Collimating Mirror Framework]] | [[File:mirror_frame.jpg|200px|Collimating Mirror Framework]] | ||
The framework itself is made from 12mm Baltic Birch and is under 36" tall. | The framework itself is made from 12mm Baltic Birch and is under 36" tall. The arcs defined by the "inside" ribs show where the spherical section mirror will form. In order to form the mirror, vacuum must be applied. This will stretch the mirror into a spherical section shape. | ||
Attaching the Mylar: | Attaching the Mylar: | ||
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[[File:mirror_test.jpg|200px|Test setup]] | [[File:mirror_test.jpg|200px|Test setup]] | ||
The mirror just reflects what is on the screen above it - the test screen in this case is just a bit less than half the radius of the mirror and is 17" tall. | The mirror just reflects what is on the screen above it - the test screen in this case is just a bit less than half the radius of the mirror and is 17" tall. In order to start testing as soon as possible, Wayne skinned the screen with kraft paper. It's very wrinkly, but it did an adequate job of being a screen. It's also what we had handy at the time. :) | ||
Here's the complete test configuration: | Here's the complete test configuration: | ||
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We used a Fein Turbo III dust collector as our vac source and it pulls the mirror down very well! | We used a Fein Turbo III dust collector as our vac source and it pulls the mirror down very well! It's pulling about 5 PSI in order to force the Mylar into the correct shape. Below is a picture of the mirror after being pulled down. | ||
[[file:formed_mirror.jpg|200px|Formed mirror]] | [[file:formed_mirror.jpg|200px|Formed mirror]] | ||
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[[file:test_flight.jpg|200px|Test Flight]] | [[file:test_flight.jpg|200px|Test Flight]] | ||
...and thus was born the world's very first amateur built fully collimated display for DIY flight simulators. | ...and thus was born the world's very first amateur built fully collimated display for DIY flight simulators. I can't stress enough how thankful I am for Wayne and his skills. Were it not for his deep understanding of the math involved, this would have never been built. | ||
Here are a few YouTube videos of the system in operation: | |||
* [http://www.youtube.com/watch?v=y67TAo9Lv5g First draw down of the mirror] | |||
* [http://www.youtube.com/watch?v=8yaDnXYlf8k My badly narrated test flight] | |||
* [http://www.youtube.com/watch?v=zogFny49zrI A walk-around of the setup taken the next day] | |||
The | The [http://www.diy-cockpits.org/coll/collimated_display.html project site] has more pictures and details on the current state of the project. Work has already begun on a 180 degree version! | ||
=== Did you know === | === Did you know === | ||