Reply to "running 2 rail cars on three rail track"

@Ryan Selvius posted:

Anybody know what the minimum curve would be for body mount couplers on 21” passenger cars?

This is a general formula.

Measure from center to center on the trucks. Multiply that by three to get the minimum. Multiply by four (or more) for better appearance. For hi-rail cars you can usually get away with something smaller than the minimum, but it depends on how, closely the cars are coupled and how much swing they have.