What is the minimum radius of a BLI NW2?

[johnb]

I am looking at building a new layout that is meant for streetcars and interurbans, these cars can make a 4 inch radius, however I am thinking about using a 7 inch radius like Kato does with their UniTram track. Has anyone used a BLI NW2 and 40 foot freight cars on UniTram track or an equivalent radius?

Thanks,

John

[dem34]

While I don't have a BLI NW2 I did in the past make a micro layout using the 7" radius Unitrak. 40' cars even with body mount couplers worked, 50' cars with truck mounted couplers worked fine and the primary power was a Kato Mikado. As long as you aren't intending to run 6 axle diesels and 80 foot flats you should be good.

[vekelly09]

I built an experimental switching layout with 6-7 inch radius turnback curves into staging.  Some Unitram tracks go down to a 6 inch radius, which poses some challenges, based on my experience.

• Although many short-wheelbase diesels can handle 6-7 inch radii, they lose a lot of traction. You need a heavy engine, double-headers, or traction tires to make up for it. Otherwise you are restricted to very short trains (3-4 cars). The fact that recent sound-equipped engines sacrifice weight for speaker space does not help the situation.
• Consider getting the heaviest engine that makes sense for your operation, e.g., a road switcher like a C420 or GP-35 instead of an NW-2.  The wheelbase will still be short enough.
• If you can find one, the Rapido SW-1 from a few years back has traction tires and handles 5 inch radius curves very nicely.  It takes a standard plug-in DCC decoder (non-sound).  The ancient Arnold S-2 switchers had metal bodies and are useful down to 6 inch radii, but are harder to adapt to DCC
• The tradeoff between body-mount and truck-mounted couplers becomes more extreme.  Truck-mounts will handle sharper radii in the "pull" direction, but tend to derail in the "push" direction. All couplers need to be compliant side-to-side, like MicroTrains; some stiffer couplers (e.g., Kato) can increase derailments.

Good luck with your plan.  It can be made to work with careful design and equipment selection.

[milw12]

Not to go too much off topic, but @vekelly09 do you have any photos or a track plan for your layout?

I do know that an Atlas GP7 (at least the ancient non-DCC version) can at least run on the Kato 7" track.

Lucas

[Kentuckian]

John,

My BLI SW7 does fine on the seven inch radius curves on my micro layout. 40’ cars with stock MTs or Accumateys are not a problem, either. True scale couplers, not so much.

[vekelly09]

Hello @Milw2

Unfortunately I don't have a a track plan but I have attempted to attach a photo of a 4.6" turnback curve with easements. 

It was a brief experiment with Unitrack back in 2/2018.  I had set up a small switching section mainly to test various magnetic uncoupling arrangements (different magnets and mixed couplers), then on a whim I added 180 degree turnbacks at each end to make a staging loop.  I tried successively smaller radii of Unitrack all the way down to 4.6" and checked what would run reliably in both push and pull modes. The survivors down to 4.6 inches were the Rapido SW-1 and an A-B-B-A lashup of Life-Like FA1-FB1 units.  Some older Atlas/Kato road switchers also worked, but barely.  (I hope the picture below works.)

[ Guests cannot view attachments ]

[johnb]

Thanks for the replies, I am close to starting a new layout

[narrowminded]

Probably stating the obvious but a transition easement on turn entry and exit goes a long way to keeping cars on the rails that otherwise wouldn't make it.  Anything that gets the turn started so that the section following isn't such an abrupt transition that the couplers have to accommodate.