I am new to all of this and have been thinking about possible track plans for N scale. I see quite a few around the room type layouts at 2 ft widths against the wall. Some terminate a bit wider to allow a larger radius for the return loop. But, even at that those are some pretty tight radius turns there, much tighter than I often see as recommended. My question is how tight can a turn in N scale be and remain functional? I understand the cosmetic and realism factor demands a different standard, but just to be functional, what are we talking here? What is safe, 10", 12"?
I plan to have the largest radius curves possible, but already I can see that some will need to be smaller, especially since my around the room planned layout will at places terminate at a 30" width for a loop. I was considering hiding the tightest part of such curves completely within a tunnel, say the first 90 degree turn, while having part of the larger radius section exiting the other side. For example: For a 30" width I could mix about a 12" rad. 90 with a 16" for the exiting 90. Is this a common thing to do?
Dave
Atlas sells 9 3/4 inch radius sectional curved track, so I would say that’s probably “safe,” but the real answer will lie with your engines and rolling stock. I model in HO scale, where 18 inch radius is generally considered the minimum. I use a lot of 18-inch curves, but I have to be careful of what I run on them. I’m a Transition Era guy, with 4-axle diesels and 40-foot boxcars. Those are fine, but I can’t run either older large steamers or newer intermodal equipment.
Be sure to plan ahead for construction, maintenance and disaster. 30 inches is the maximum recommended “reach distance” across a layout. If you’ve got two 30-inch shelves meeting in a corner, the geometry dictates that the it’s almost 45 inches from the edge of the layout to the corner itself. Putting a tight curve in a tunnel that distance from the edge would likely be something you’d regret.
from the Layout Design SIG - note: Prototype curves are usually much broader than model curves following these quidelines, however there are exceptions, the prototype will use very sharp curves in tight spots. [^o)].
Here are some curve radius guidelines based on the lengths of your longest pieces of rolling stock.
2X - Some model equipment may be able to track reliably on 2X their length, but this is generally considered pushing it.
3X - Making your curve radius at least 3X the length of your longest cars gets reliable tracking around curves, but looks toylike.
4X - If you make your curve radius at least 4X, your longest cars will look much better on curves.
5X - If you make your curve radius at least 5X, your longest cars will couple easily with minimal manual fiddling of the couplers.
That distance concerns me too, as it would be in a corner. Since it would be in a tunnel I was planning on creating access to that corner coming up from underneath and through the benchwork. I would have an access hole cut the inner diameter of that track. Also, the hill itself could have a removable top. This way it could be detailed off the layout and then set in place and made to be removable.