I model the NP, GN, SP&S, & UP in the early 1940’s. My roundhouses are filled with brass (prototypical articulation) articulated locomotives. I am currently planning another layout in a big space 35x70 and am wondering about curves. I use spline roadbed so I get natural easements. My last big layout had 36 inch minimum curves and these proved to be too tight. I would really like 60 inches as a minimum for the main but would have to make some compromises.My new W&R passenger cars require a minimum radius of 42 to stay coupled together, but look toylike twisting around such tight curves. I have many brass locomotives that operate like the prototype in that the rear engine is fixed and only the front is hinged. Can someone with experience enlighten me about curves. Any help would be greatly appreciated. XSD
I would suggest you follow the advice of Paul Mallery - who suggested 48" radius was the ideal mainline radius for HO. 48" radius with proper easements should provide good operation and reasonable appearance for all the equipment you have described, and still allow good planning opportunities in ther space you described.
Sheldon
I’m not exactly sure what you need from us. You have the locomotives, can you not just mock up several successively tighter curves with known radii and try them all out? I have a latest issue of the Sunset Brass CPR Selkirk 2-10-4 that runs okay on a stated minimum of 30" radius. On some brass models you would need 40" curves or better for a ten-coupled, while the BLI equivalent 2-10-4’s do fine on 24".
Because brass models have a history in many cases of shorting out when metal parts touch other parts on curves that are borderline tight, you really have little choice but to do the trails I suggested earlier. Get it from the horses’ mouths.
Crandell
The only “curve sensitive” items I have are Walthers passenger cars which derail on 28" radius curves. I prefer my mainline track centers to be spaced at 2 ", so my main issue would be preventing sideswipes. Through trial and error I determined that at 42 and 44 inch radius, my BLI N&W A on the inner track would pass an 86 foot auto parts boxcar on the outer track without touching, so everything else would be OK. Then along comes an Akane EM-1 with prototypical articulation. This thing really overhangs, so it’s looking like I might have to rethink my standards, and then Bachmann’s EM-1 comes to the rescue. Looks like the Akane is going in the display case.
Thanks Sheldon!
That was the answer that I was looking for.
Also remember that you can have compound radii for any given curve, so for example you could start with 48" on one end and have 60" on the other, this can help a lot. IE, decreasing/increasing radii curves are very prototypical and help in the modeling world too.
Richard
I have a friend–a former brass collecting “heavy hitter” who in the past routinely blew a few grand on brass at the average Timonium Train show.
We had a whole crew who helped him build an attic layout in a historic house he owned, and we played with a lot of HO brass there at “the lodge”.
If I recall correctly, his mainline curve radii were 48", combined with 2% to 3% grades.
I have owned and/or operated the following articulateds on his layout without any problems at all: the Key Rio Grande L-105 challengers, PFM Rio Grande L-131 2-8-8-2’s, Overland Models B&O and Union Pacific 2-8-8-0’s, Precision Scale Western Pacific Challengers, Custom Brass C&O H-7 2-8-8-2’s, etc. Also big monster 2-10-4’s like the Hallmark/Samhongsa “Super Crown” Santa Fe engines were just fine.
In real life and the model world, the 2-6-6-2’s are more forgiving and they went a lot of places the big guys didn’t always like to go. For those with lesser radii, I recommend you consider the 2-6-6-2’s as they can be a huge amount of fun to play with!
John
The Northern Pacific challengers are quite a bit bigger than the UP versions, I have both as well as the aforementioned 2-8-8-2’s , 2-8-8-0’s as well as the Z-5 2-8-8-4’s. It sounds like 48 inch might be the way to go. Thank you. I do like the 2-6-6-2’s, one of my favorites.
Due to the expense involved in layout design changes, you might want to consider laying a temporary curve radius and just testing the very largest engines you have to be certain they will work.