Then there is the distance you want to sit from the screen. If too close, you or part of the simpit will be in the beam of one of the projectors, casting a shadow. You don't want to sit too far either.
A spanned view is best projected on a straight continuing screen. Therefore the angle that the left and right screens make with the center screen is important, as it cannot be too big. I found that within my confined attic space with slanted roof, the screens make about 135o angle which results in lines seem to become cracked from one screen to the other. A very annoying effect, that is very unnatural and distracting during flight.
As can be seen, I had some problems in getting the same screen size for the
three views; The center projector is farthest from the screens and had to be
completely zoomed out, while the other two had to be zoomed in.
Although I don't have space to try, I believe a better result could be
obtained from the below setup, as it does not suffer from cracked lines
effect. Also the view is wider, which will improve the immersion effect.
Another thing to consider with three projectors is the heat they generate. Each one is good for some 250 - 300W, which quickly heats up the room (especially when ventilation is limited due to window blinds etc).
I made the screens from pre-painted cardboard. By clipping them together,
they stand by themselves, without wrinkles. They can easily be stowed as
well.
