OK, I'm going to run  through a few things, starting with what may have been an effect of conversion from DAZ Studio.

1: Diffuse, and sometimes Specular, Colors are odd. When a texturemap is used, a white diffuse color works best. Any tint in the color setting mixes with the texturemap, which can have odd effects. Dark Specular Colors are appropriate for non-glossy surfaces. A large value for the Highlight size is also good, but a value of 1.0 is likely rather too high.

2: Transparency Fall-Off is consistently set to 0.6 giving odd results. Some things need to be transparent. Most don't.

Next, some Poser-specific stuff.

3: Texturemaps in different folders which have the same filename can confuse Poser.

4: The PNG files to provide the library pictures should be a lot smaller. The images provided with Poser's default content are 95 pixels square. Poser doesn't crash, but small images fit with the Poser library interface.

5: Everything but the repainted F4U could be a Poser prop.

6: Some of the material names you used were awkward: "material23" is OK for something with just one material. "Drop_Tank" tells the user something. A useful improvement would be to have the bombs and bomb-racks as seperate materials (no need to change the texture) so they could be hidden, allowing the plane to be shown after it has dropped the bombs, simply by making the bombs transparent and non-reflective.

7: The UV map for the backdrop is clumsy. It wastes a lot of space, and thus comsumes RAM it doesn't need to.

And a few quibbles:

8: That's much bigger than a ten-gallon drum, and I have my doubts about the red warning label. I suspect it came into use much more recently. The packing crates resemble the colour of old ones I saw as a kid, basically grey, but what I was told was WW2 "salvage" was thick plywood, rather than planked. But this was on the other side of the world.

Overall, it's far better than my early attempts at creating models.