The higher the poygon count the more power your PC need to display the model. Multi LOD means that the MDL has more than 1 model.
The game will change to a more simple model with less detail as the aircraft/object is farther away from the player. The player probly won't see that the model has changed unless they are looking right at it when it changes. By using LODs you can put many aircraft/object on the screen with out the game becoming a slide show.
F4F4 LODs. This a gif so you may need to click on it.
The rules I use for making aircraft are no single engine aircraft should be above 5,000 poygons for the full detail/close up model and each LOD should have a polygon count drop of 25% or more. For a fighter the LODs should be LOD 100 (full detail) 5,000 poygons, LOD 75 3,750 poygons, LOD 50 2,500 poygons, LOD 25, 1250 LOD 10 is vary small so it is around 200 to 150 poygons.
My normal aircraft poygon count is lower. The norm is 4,000+ poygons for LOD 100 (full detail), 3,000 poygons for LOD 75, 1,500 poygons for LOD 50, 500 poygons for LOD 25, 200 to 150 poygons for LOD 10.
Since the Read me seem to say editing is okay. I could port the model back into gMax and simplifie some things like the wheels. This would free up some ploygons that I could use to add a Pilot and Co-Pilot to the model.
The Greg Pepper HU-16 Read me say:
"Important: This is Freeware! It may not be used commercially in any way. This simulation is made for the sole purpose of entertainment for fellow flight simmers. It may NOT be sold or distributed on any disk or CD, regardless of whether the disk or CD is allegedly "non-profit". I reserve ALL rights to this model."