It's variable due by your tastes.
It's can just barely squeeze by a nineteen inch radius curve. If you do not have secured track, beware! We were running a Niagara around his layout. We had not barely built it, so the track was loose sectional track from Atlas connected by rail joiners. I decided to open the throttle wide around the next corner, and I hadn't seen that the track had move slightly, tightening the curve. The locomotive jumped the curve and fell useless on it's side like a dead rock. No slides, nor any other action. It just plopped off, with a great "Bam!". (The layout was just plywood, painted green.) The domino effect played as the whole consist, connected by couplers, tumbled until the last few cars. About two-thirds of the train was on it's side with almost enough room away from the tracks to allow another train to pass.
So, be careful! I would recommend twenty-one inches in radius and above. If you chose nineteen inch radius, be sure you have just fine curves. However, it's hard to not.
Cheers,
Joshua
It's can just barely squeeze by a nineteen inch radius curve. If you do not have secured track, beware! We were running a Niagara around his layout. We had not barely built it, so the track was loose sectional track from Atlas connected by rail joiners. I decided to open the throttle wide around the next corner, and I hadn't seen that the track had move slightly, tightening the curve. The locomotive jumped the curve and fell useless on it's side like a dead rock. No slides, nor any other action. It just plopped off, with a great "Bam!". (The layout was just plywood, painted green.) The domino effect played as the whole consist, connected by couplers, tumbled until the last few cars. About two-thirds of the train was on it's side with almost enough room away from the tracks to allow another train to pass.
So, be careful! I would recommend twenty-one inches in radius and above. If you chose nineteen inch radius, be sure you have just fine curves. However, it's hard to not.
Cheers,
Joshua