Not sure of how many will affect your sim, but it's going to be based on your computer, not the sim itself.  The better the computer, the better a high poly plane will render.

To create poly's, which program are you working in?  Is it Max or FSDS?  I don't know about FSDS, but in Max, you select the object, go to polygon mode, right click to bring the quad-menu up, then select 'Create Polygons.'  After that, you just start clicking on the vertices to trace out the poly you want in a circular motion and it will appear once you click on the first vertex you selected for the second time.

Clear as mud? 

aussiewannabe wrote on Sep 28^th, 2009 at 5:31pm:

Every shape you see in the sim is made up of polygons, which are flat 2D shapes. The more polys used to make a given shape, the harder a computer has to work to display it.

So how do we take a bunch of flat 2D shapes and create 3D objects?

A good analogy would be to think of a round cross-section fuselage as being made with a bunch of Popsicle sticks glued together along the edges.

If the sticks are very narrow the fuselage will look round (user aircraft). However, if you make each individual stick wider you can use a lot less for the same diameter (AI). This will be noticeable when viewed up close, but make it easier for the computer to display them.

This is all done at the modeling stage, as end user we really have no control over it. Except in the decision of what addons we want to use.

Hope this helps,
Joe

If you are working on an AI or FS9 model then low-poly is important. If you are modeling an FSX plane then poly count is not the problem it used to be. Many FSX models coming out now are way over 100k on the poly count