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Guest chameloon

Great idea or not for 180

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Hi,First I apologize for my bad english that isn't my native tongue...I was thinking about a new concept for a 180

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Theoretically it is possible to achieve this effect with a correct zoom value in FS, a calibrated lens and a screen correctly shaped.Not too easy to do though

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Yes... and theoretically, modern aerodynamics can't explain a Fly's way of flying.I thing we would need special software to "deform" the image to be projected on such a screen, and the corresponding projection lens (which would be similar to an Imax projector lens)to give you even lighting on the entire field of view, and probably alltogether about 10 times as expensive as 3 projectors (which is already too expensive for most of us).It would be the best choice, just not affordable to many people, though.Maybe someone on the list is illustrated in the complex field of Optics to give us some advice.Cheers.

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The only way I know of bending light to 90 degrees is with a prism, but then you'd get some strange lighting as the lightwaves are split. Certainly a lens could be constructed to allow such a feat, but it would be very expensive to prototype, and I am not aware of such a lens that's available to the public!

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http://members.chello.nl/p.leerentveld/simulatievluchten.htmIt is in dutch, look at the button rightclick on "Bekijk ons demonstratie filmpje"This is, believe me or not, done with ONE videoprojector.The image is split in a left and right part and via mirrors split to the side, giving a very spatial feeling.I posted a drawing of this setup in this forum once (few weeks ago), caanot find it on my HD now.regards norberthttp://home.wanadoo.nl/norbert.bosch

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Is this the pic you're looking for?I'm wondering how they kept the image in focus. The screen is curved so they had to focus on either the center or the ends. Either way wouldn't one or the other be out of focus?Richard

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Yes that's the pic I made from a drawing that I saw about this sim in a Dutch magazine. (Piloot and Vliegtuid , Pilot & PLane).In that article the builders of the sim state that they will commercialise their visual system.At this moment they have 2 products for sale, engine instruments & radio stack.Btw, I am in no way involved in this, so this is no promotion.RegardsNorbert Bosch

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Honestly, I wonder why we haven't seen folks experimenting with suction formed mylar mirrors. Yeah, some of them are large, 11ft in radius etc., but smaller projects could make one work. With all the other amazing things I see around the cockpit building scene I have yet to see any collimated mirror approaches. It's a matter of time I suppose.

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The simulator company I work for (as an advisor/engineer) uses mylar mirrors in their applications. The great thing about these is that the base can be hand-crafted to the desired shape and size, and when you're happy with the layout, you make a very small hole in the middle, tack the mylar sheet to the edges (and you MUST ensure it's an airtight fit) and suck the air out. The hole is then carefully plugged. Since the hole is very small (no more than 10mm diameter), the small recess it can sometimes leave isn't noticeable at the distance the screen is placed from the viewer.One final thing, the base is usually crafted from fibreglass, allowing a tough, lightweight and smooth finish. This is very important as you don't want any wrinkles showing on the mylar.If anyone wants more info/tips on this, feel free to contact me at ceawlinjones(AT)hotmail(DOT)com (anti-spam) :(

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Whoops, got far too many responses to respond personally, for that I apologise.So you all want to know how it's done? Here's a cheaper variation of the process:First of all, you will need to work out the curvature of the screen. Not easy, as typically a design program is used to work it all out, but generally speaking, the light from the projectors has to be projected back towards the viewers. The problem is to avoid issues with having to specify a set viewpoint for the pilot, as any deviation would just look wrong. Typically, the focal point would be set to the rear of the cockpit, thus allowing some degree of flexibility in pilot positioning so that he/she doesn't get motion sickness. As the projectors (in commercial simulators, 3 or 5 projectors is normal) are mounted above the cockpit, the screen will have to be tilted back at the top to allow the light to be directed into the cockpit. Imagine a "(" character. If you cut it in half and keep the bottom half, this is what you're aiming for. Also, the screen will have to wrap around the cockpit, otherwise the edges to the left and right will look out of proportion. You should be aiming to keep the distance from the edges to the projector the same as the distance from the centre to the projector.Once you have worked out the rough size, shape and position, you now need to make the frame. The initial framework will be required to both keep the same shape throughout its use, and also to hold the weight of the materials. You can use whichever materials you want, bearing in mind the weight requirements. It DOES get heavy! Using wood panels to create the backing plate is fine, however the smaller the panels, the more finely curved you can get the backing plate. One technique you can use is to use copious amounts of filler to achieve a smooth(ish) curved surface. You can test the correct shape by placing the screen in position and using the projector (monitors are not suitable for this, although the technique can be adapted) to see where you need to adjust the screen. Now a small hole needs to be drilled in the centre of the screen. Anything bigger than 10mm will be noticeable to the viewer later. This is for the vacuum forming process which will be explained later on. You may also want to experiment with various methods of sealing the hole afterwards, but please make it temporary, as any airleaks later will be hard to rectify as you won't be able to open a hole for the vacuum. Usually a small, hard, solid plug with a is used with a rubber gasket. Once your screen is finished, use very fine wet and dry sandpaper to make the surface smoother than a baby's bottom. This means no creases, lumps, bumps, hairs, foreign matter, the odd moth (it has happened!) are to be left on the surface.Now you are almost ready to affix the mylar. Using several pairs of hands here is important, as you will struggle otherwise. Assuming the screen has a light curve, no adjustments need to be made for the mylar, as it only stretches to a limited degree. The mylar must now be fixed to the border of the screen. Use a strong adhesive, as this will effectively be your only method of permanently attaching the mylar. If you plan on gluing the mylar onto the backing plate, I would recommend a gel-based slow setting anaerobic adhesive (in other words, something that won't run, won't set within half an hour, and won't set quickly if left out in the open. We use an industrial glue, and I don't know what it's called). It is very important that you get an airtight seal here. I recommend using silicon based sealant to ensure a good, airtight seal. Carefully tack the mylar sheet onto the frame, making sure the sheet is not kinked, creased, wrinkled, folded, or generally any other shape than smooth. It also needs to be kept taut in all directions.Next job is to grab your hoover, stick it over the hole you created, and gently suck all the air out. Provided you have made a good, stable base, and the mylar is FIRMLY fixed to the screen (I recommend waiting overnight for the adhesive to bond thoroughly), you will find that the sheet will have stretched evenly over the backing plate. You may need an assistant, using a wide, soft bristled brush, to gently work from the edges inwards to the centre to remove any fine creases/lumps/bumps/air pockets that may have developed. If you have glued the mylar to the backing plate, this is also a good way to make sure the sheet is spread evenly over the glue, and has not formed any pockets etc. This is why I recommend slow setting glue. Now you will have to plug the hole. One method you may want to try is to get a soft rubber disc, a large eraser will suffice provided it is soft and pliable. This is placed on the mylar side of the hole, and pressed very firmly. At the same time, the hoover nozzle is slowly, and slightly, removed from the hole, leaving just enough room for the plug. Now the plug is inserted, made airtight, and the hoover switched off. The assistant may now remove the rubber, hopefully leaving a flat section of mylar behind.If you have glued the mylar to the backing plate, you will not have to worry about the vacuum seal too much after the glue has set. If you haven't glued it, you will need to check the centre periodically to ensure no air is getting through. A general check may be required to ensure no other leaks have occured. To rectify any leaks, you may need to glue over them, and re-vacuum the screen.After all that, you should have a nice, professional looking reflective screen for your simulator. Or you may have a quirky mirror for the hallway ;)If there are more finer points you wish to cover, please feel free to email me with the exact requirements. I don't respond well to vague questions on how to build one, not after this lot I typed up! :(Same email as before, ceawlinjones(AT)hotmail(DOT)com, if you wish to ask any questions. I will also answer technical questions about any engineering subject if you ask nicely enough!

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