A surprisingly basic N Scale question about curve radii

[nkalanaga]

Mike:  The prototype has problems with long/short pairings.  One BN Special Instruction from years ago, for a mountain division, said nothing under 50 feet long should be coupled to anything over 80 feet long.

[C855B]

Mike:  The prototype has problems with long/short pairings.  One BN Special Instruction from years ago, for a mountain division, said nothing under 50 feet long should be coupled to anything over 80 feet long.

Conversely, UP ran ore trains with the jennies coupled directly to DD35s - 88' vs 24'.

[Jimbo]

WOW, I must be old.

“Back in the day”, 15” courses were considered BROAD!  Now we’re asking if they’re too TIGHT??

Jim

[garethashenden]

WOW, I must be old.

“Back in the day”, 15” courses were considered BROAD!  Now we’re asking if they’re too TIGHT??

Jim

A 10 degree curve is basically industrial track only, and yet it’s 43” in N scale. So yeah, 15” is pretty tight.
The tightest curve on the line I’m modeling was 6 degrees and the whole route had a 25mph speed limit.

[randgust]

The absolute tightest prototype curve I've ever seen in my life NOT on an industrial siding was 33 degrees.

That translates to 176' radius, which translates to 13.2" in N scale.

That was so tight that a Chevy Suburban hirail fell inside off the curve if you didn't keep it up to 25mph to slam it to the outside rails!

The location, by the way, is "High Falls Curve" on the West Virginia Central, former Western Maryland, in West Virginia on the ex-Bergoo line out of Elkins.

The New Tygart Flyer train out of Elkins still runs up to that curve.

[robertjohndavis]

I love seeing an accomplished modeler whose work I admire ask a “surprisingly basic” question. It’s a good reminder that all of us can continue to learn and grow.

[Missaberoad]

can you setup a mock up and test some of your more questionable equipment combinations? Atlas 89' flats with various locos and smaller cars would be good for a torture test.

[Point353]

WOW, I must be old.

“Back in the day”, 15” courses were considered BROAD!  Now we’re asking if they’re too TIGHT??

Jim

"Back in the day", when most locos and rolling stock were equipped with truck-mounted couplers, Atlas curved track with a 9-3/4" radius was common.
MiniTrix had/has some curved track with a radius of about 7-1/2".

[Jimbo]

"Back in the day", when most locos and rolling stock were equipped with truck-mounted couplers, Atlas curved track with a 9-3/4" radius was common.
MiniTrix had/has some curved track with a radius of about 7-1/2".

Back in the 70s, my friend had a small layout with those (7 1/2”?) curves, and would run his passenger train (Minitrix F-unit + 4 or 5 of the old Model Power streamlined cars) on that layout.  Even to my 10-year old eyes, they looked toylike.  And I loved it!!

9 3/4” was common and considered adequate, but 11” was viewed as more realistic.  15” was considered “broad.”  Even though the 80s and early 90s.

Take a look at track plans from this era and you’ll see.

I personally find 15” curves to be the best compromise for the space I have and equipment I run.  And I’ve never had issues.  Needless to say, I’m a transition era modeler!  (Mostly 40’ cars.)

Jim

[Point353]

Back in the 70s, my friend had a small layout with those (7 1/2”?) curves, and would run his passenger train (Minitrix F-unit + 4 or 5 of the old Model Power streamlined cars) on that layout.  Even to my 10-year old eyes, they looked toylike.  And I loved it!!

9 3/4” was common and considered adequate, but 11” was viewed as more realistic.  15” was considered “broad.”  Even though the 80s and early 90s.

Take a look at track plans from this era and you’ll see.

When N was relatively new, it was not unusual to take a track plan for HO (1/87) scale and reduce it for N (1/160).
18" was a common radius for HO curved sectional track. 18" x (87/160) is almost exactly 9-3/4".

[nkalanaga]

Mike:  Very true, and we can as well, if we have straight track, or very broad curves.  The BN restrictions were for tight curves, usually on grades, in the Cascades and Rockies.

[mmagliaro]

Okay, I'll be the contrarian trouble-maker here.  My previous PRR layout years ago had some 14" and 15" radius areas, and there was definitely equipment that was troublesome on those curves, notably 80' passenger cars, and long wheelbase steam.  'Troublesome" meaning that geometrically, no way was the equipment going to make it.  Passenger cars would hit each others corners (unless I stuck out the couplers further, which I hated), or steam locos would climb out because heck, 4 or 5 drivers in a line can only slide sideways so much.  So I swore when I built my current one that no way would I have anything less than 18", and I do not regret it.  I can back a 20 car train through those curves without trouble, and the days of anything ever touching or climbing, even when close-coupled, are behind me.  For the same reason, I firmly decided that the olden-days "2% maximum" goal for grades was too much.  I have areas that are 1.7%, and I wish it was less.
Ed, I know you're not running big ol' 2-10-2's, so enginewise, you should be fine.  But 10 feet of train with 89' cars in it gives me pause.

[nkalanaga]

Somewhat off topic, but here's a couple numbers from EMD's GP38 Operator's Manual:

Minimum Curve Radius
     Single   140'
     Coupled to 50' Car   302'

So, by itself, it will take a 10.5 inch radius curve, but coupled, it needs at least 22.5 inches.