Any material that I could use to make smoke trails for 1/144 F14 besides cotton? Cotton is kinda larger so I need another material

The F-14 is a pretty clean burning bird. I wouldn't add a smoke trail. If you mean a contrail, what you see form the ground, you could use cotton, but there's usually a gap between the exhaust tip and when the exhaust fumes cool enough to actually condense into a visible vapor. That gap would look kind of strange unless you were doing a box diorama.THe last really smoky fighter was the F-4 Phantom. P-3 and C-130 leave a thin but visible (under certain conditions) trail, but I wouldn't try to replicate this. The only other smoker, and I don't know if the current engines are as bad as the old ones, is the B-52.