I was going to start my own thread, but the question is of the same topic.
I have a 2-6-6-2 Mallet that I want to use on my layout to run coal unit trains (among other things). Is an 11" radius going to be large enough for this huge engine? I'm not so worried about the cars, as I'm using mostly 33' hoppers.
And then a second question: If 11" is okay, or if I need to go to 17" or even bigger, should I use that as a standard for all radii? Or should I just try to limit the Mallet for coal use, then only make the turns along that route the larger size?