I'm modeling a small park with a childrens rideable train surrounded by my HO train lines. What is the smallest circle I can have with N gauge track?
Kato makes 115mm curved track, which is a 4.5" radius. You'd be limited to trolleys and the like. Thomas might work on there, I'm not sure.
you can do a 12 inch diameter in flexi Peco Streamline N gauge/scale
some 0-6-0 locos will go around unmodified , other (same model) loco will need center driver flange removed. and some shave off the loco cab roof to gap betwee loco and tender - trial & error.
the plymoth switcher will do 12 inch - the 44 tonner will go around with some removal of the 'pip' that hold the bogie/truck to the chassis
the 'Brill' trolly can manage 12 inch circle
for couples use the long type , rapido or EZ
cant seem to post photos of my layout with tight curves - will keep trying