I know this is an often-asked question - please bear with me.
Depending on what models are used, what would the members say is the minimum radius that some standard gauge (32mm) 2-rail O Scale models can get round? Here in the UK, with smaller houses, and therefore smaller layouts, it's an important question.
So, 36inch..? 24inch..? Maybe less, at a push..??
How about 9+5/8inch.? Yep, less than 10inch, radius.....
Here's my latest little bit of irreverant & silly modelling - a 2ft-square 'pizza' Micro layout, called "Enderless", for hopefully obvious reasons....
Then I got carried away, and laid a middle rail, for On30. As the layout can also use DCC as well as 12v analogue, a bit of fun can be had - a bit like watching NASCAR, only smaller....
On30 loco and caboose are Bachmann, the O scale critter is an old Atlas/Roco shortened & modified to an 0-4-0, and Atlas/Roco Bobber Cabooses, all with standard Kadee 805 couplers, fitted at standard settings, not extended out.
Just a little bit of fun, but answers an important question!!!!!