Getting ready to lay the first curves on my son’s layout, and I’m wondering what radius is too tight.
I’ve got a bunch of 9 3/4" pieces, which I assume are acceptable since they are so common. Now, the main loop of the layout has parallel tracks the entire way around, so I need to find another radius to run in parallel around the curves. I have a bunch of what I think are 8" radius pieces that fit nicely on the inside of the 9 3/4" curves. But, is that too tight?
I don’t have to use them - I could use the 9 3/4" for the inner loop and lay flex track for the outer.
Did some searching of the forum (should’ve done that before posting!), and it seems 11-12" is the common suggestion for minimum radii. So, it seems 8" is definitely a no-no.
Would you agree that 9 3/4" should not be used? Thanks.
Not true- the smaller-radius snap-together and sectional tracks are thoroughly aedequate for use with smaller locos, like mosy any GP or F unit, and smaller steamers. You’ll encounter issues with larger steamers and certain diesels (DD40AX and some SD locos are a no-go). If you’re going for modern diesels, I’d avoid the smaller raduis but for older transition-era locos and rolling stock you’ll be fine. Just know that with less than an 11" radius your longer passenger cars will look ridiculous (overhang city!) and TTX/Gunderson type intermodal equipment is a 50/50 that it won’t negotiale well. \
I’ve been working on a 2x4 coffee table layout with a quite-tight inner radius curve of about 7.5" at the tightest (see my blog! Updates tomorrow with scenery!), but every section on my tracks is Atlas flex and medium-radius turnouts; soldered, aligned, and filed. I can run equipment most guys would never dare on those tigh turns, without a hitch!
Derailments are far more likely on the smaller radii sectional track. Heck, I can run Intermountain F units at full-speed with a 15-car train around both loops and any turnout, and I’ve yet to derail! That’s because of the lack of hinky joints mid-curve.
I’d say consider your rolling stock and locos first, but be sure to put some real careful planning and effort into your track to ensure good rail-running
all depends on the equipment your son will want to use. Mine loves autoracks and coaches.
Through the grapevine (NMRA and LDSIG, and long time ago also Linn Westcott) I heard a 1:4 ratio is for great looking, but a 1:3 ratio is OK. So multiply the length of your longest car by 3 and you will have a good minimum radius. A 1:2.5 ratio is the smallest ratio I would dare to use .(an indication of the switch number is in N-scale half the minimum radius) A 1:2 ratio is considered pushy against the technical limits. Applying the 2.5 and the 3 ratio is giving the following results:
a 50 feeter in N-scale needs a 9.4 to a 11" min radius and so a #5 switch.
a 70 feeter needs a 13" to a 16" radius and a #7 switch.
a 90 feeter needs a 17" to a 20" radius and a #9 switch.
BTW pulling through much tighter curves is no problem, but once they get the idea that pushing a couple of cars is nice too, you will be glad to have set appropriate standards.
Depends of the type of locomotives and rolling stock you want to use. Small locos and short cars can handle tight radii. Bigger equipment needs larger radii.
8" is pretty small. 9 3/4" is usually considered a minimum radius for the smallest layouts. 11" is a good compromise between small radius that can handle larger equipment. I think even Athearn’s Big Boy can negotiate 11" curves without problems (but it’ll look funny doing it!).
Only you can determine radius size by the type of equipment you want to run and how much space you have for a layout.
I went back and looked at the original layout plans, which call for a minimum radius of 12". Not knowing what kind of equipment we may want to run in the future, I’m going w/ 12" for the inside loop and 13.5" for the outside loop, using flex track for everything.
I’d avoid 9.75" from an appearance standpoint. It can work in a tight industrial area where it makes sense, but if you’re modeling a main line railroad, they’ll be ridiculous looking. On my layout, I’ve limited my minimums to 15" (available as sectional track in the Atlas c55 line), and that’s only when the return loop is covered by scenery.
Try to keep your curves as broad as possible, despite the equipment you’ll be running. It’s better to design your trackwork to accept just about anything rolling stock wise, than to limit yourself to short cars and engines because of a planning error.
Any tighter than that, and things just start looking silly!
Spookshow’s Model Railroading is one of the best in-depth N Scale websites – With a frank discussion of trial & error lessons learned from apx. 1/2 dozen N Scale layouts. Carefully check out each layout experience under Spookshow’s Confessions of a Mediocre Modeler webpage.
At Layout #1: *"*In my next layout I may have one tunnel just for variety, but it’s going to be very small and very easy to access. And I amdefinitely going to avoid anything like the two narrow-radius, 180 degree curves I employed. Guess where all the derailing happened? Next layout, nothing tighter than 19"-radius, 90 degree curves!"
The bigger the easier. On other sites a new Kato SD70ACe was tested and the tester said while yes it did go around the 11" radius, it didn’t like it. He suggested 14" min. If you have the room, I would say 15" min outter main, 13" min inner main. I have a 57’ mechanical reefer for christmas sitting on a set of 11R curve track, while it works fine, the overhang is kind of, well, annoying. Now if you don’t have the room, like me, you could easily go wtih 9 3/4, shorter cars (under 50’) and smaller 4 axle lokes (1st gen diesels) in some spots, and 13/11R for main loop or in my case since I’m looking at Kato Unitrack 12.375/11R. But again it also depends on you. If you don’t mind the look and it works better, you can go with the smaller curve.
On the past, I have used Peco Nscale code 55 track and avoid any radius as far as possible under 17"; I beleive it was a minimum for a good looking in the curves even if big steamers overhang a little bit. (see picture of my port Allen) Straight turnouts were n°6 and a few n°8 curved.
Now I am on the way to expand the layout and the plan on which I am currently working avoid any radius under a minimum 19" in Nscale.
Mainline will operate whith only n°8 Fastrack turnouts for crossover or diverging route; yards are with Fastrack n°6 turnouts as some of the branchline. The period I am modeling use mostly 40’ boxcars and 33’ hopper -1930/1945’s- but always with a 19" minimum radius. I find n°6 acceptable for this period.
For the now more modern equipment and often see longer cars, n°8 is I beleive, the minimum.
By example on the picture below, you see my under construction plan yard and the turnouts are all n°6.
If I have used n°8 the full east ladder/turnouts system would be only one small feet longer, so if you have some more place, and not so much more, try to use bigger radius and bigger turnout anywhere.
They are better looking and the roaster will run better anyway.
I agree whith you and the beautiful pictures you publish are more than any word about big curves.
Now, because I am in a plan stage I see that’s it’s really possible to put broad curves and bigger turnouts whithout eating so much place. A 15" radius is so sharp but a 19" radius (only 4"more) is so delight to see.
