11'' radius turns

Discussion in 'N / Z Scale Model Trains' started by Switchman73, Oct 9, 2006.

  1. Switchman73

    Switchman73 New Member

    I am switching from HO to N. I have a fair share of HO stock, but no N scale. I am wondering how well larger engines (6axles) and larger cars, such as center beam lumber cars, longer tanker cars and passenger cars run on turns as little as 11 inch radius? Can anyone help?
  2. nolatron

    nolatron Member

    You probably won't get a 6-axle engine around an 11" curve. It might make it a few times, or once, but I don't think you'll see a 100% flawless run through them.

    I've always stuck to 19" radius or higher or my previous layouts because the longer cars and engines will run and look better on them.
  3. Triplex

    Triplex Active Member

    More accurately, many 6-axle engines are built to run through 11" (the Kato SD80/90MAC, the longest 6-axle diesel available, can squeeze around 9") but that's kind of irrelevant, as they often won't stay coupled to cars on that radius. 11" in N equates to 20" in HO, to give you an idea.
  4. nolatron

    nolatron Member

    Ah, yes. Better explanation.

    Kinda like how my Aristo-craft says for their G scale Dash 9 the minimum radius is 8ft curves. Sure, it squeezed itself around the curve, but any rolling stock I tried on it got thrown off the track. Needed more like a 10ft or bigger in reality.
  5. LoudMusic

    LoudMusic Member

    A friend of mine was trying to run an SD40 or somesuch on a 4'x8' HO layout and had no end of troubles. But he sure was proud of his big six axel up against my piddly old F7s (of which I had an ABBA set).

    11 inches in N Scale equates to about 144 feet in the real thing, which I'm told is the real world's minimum radius. That means they're not likely to be running any big equipment over it. I believe, someone correct me please, that current minimum radii are upwards of 250 feet, which translates to 18.75 inches in N scale for your six axelers, which is pretty much what nolatron was getting at ;)
  6. SeriousSam

    SeriousSam Member

    Ive never had any trouble with my big six axle locomotives on my break in figure eight. It uses the nine inch radius curves. But like its been said, it just doesnt look good.
  7. MCL_RDG

    MCL_RDG Member

    I am with...

    ...with Serious Sam. I had a Kato UniTrack 9-3/4" turn in 3 crucial places on my layout. I ran 35-40 cars with (3) SD45s, (2) SD35s etc. I even backed the trains on occasion. Heck- one of the 9-3/4" rads was the back lead to a yard throat- quite busy running forward and backing manuevers (Again, backing 20+ cars to pick up strings from the yard tracks.). Only real problem I encountered was an MT Empty 35' coal hopper. Some would say it wasn't pretty, some would say it was exciting to watch (that would be me).

    My 2 bits.

  8. pgandw

    pgandw Active Member

    The Layout Design Special Interest Group (LDSIG) rule of thumb for curve radius is here:
    If you read through my comments, you will see that with truck-mounted couplers (common in N) you MAY get to reliable operation, but no coupling or uncoupling, on a radius equal to twice the length of your longest car or loco. Testing of each piece in conjunction with other cars of various lengths would be needed.

    2.5X should be pretty much achieveable with truck-mounted couplers under virtually all conditions.

    Note that a scale model of an 80ft car is about 6.25" in N. Marginal operation would be expected at 12.5" radius (individual testing required), reliable operation with truck mounted couplers at 15" radius, and reliable operation with body mounted couplers would need the full 19" radius recommended by others.

    Something to keep in mind is that an 80ft car in N is just as long as, and takes just as much room to turn as a 40ft car in HO. An 89 ft car in N is almost equivalent to a 50ft car in HO.

    All of the above has nothing to do with looks on curves.

    The NMRA's recommended practice for curves for both rolling stock manufacture and layout design is here: http://www.nmra.org/standards/rp-11.html
    Except for club and some N layouts, very few modern era layouts come close to complying with the RP. But few modern era and passenger car modelers realize that they really need to go up so much in radius to achieve to operation and looks they desire.

    my thoughts, your choices
  9. Triplex

    Triplex Active Member

    Note that the various NMRA standards do not correspond to the commonly used radii in the different scales. I would expect most commercial equipment to be designed for a given radius that is often used. Note that, for example, none of the classes of HO equipment has 18", 22" or 24" as a minimum. I don't know if I've ever seen an HO plan with 40" minimum curves. 36" is fairly common on large layouts, but I've seen more 42", 44" or even 48" than 40". Their recommendations would force 32" curves for HO SD40-2s, and I don't think even a brass model requires that.

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