NOT considering aesthetics-- consider it totally hidden– performance only-- what would you suggest as the absolute rock-bottom minimum practical radius for HO scale, long trains (30-50 car coal-drags, for example) as well as running with long equipment such as passenger trains with 85-foot cars? Particularly with respect to coupler performance, car separation, tendancy for “stringing over” on the curve, etc–
I’m not going to be running those “reduced length, selectively compressed” Athearn / BevBel passenger cars. I’m not going to modify anything for “tight curve” performance, and I probably want to “close couple” everything.
If something has to give, it will be the curve (making it larger radius).
Can I get away with 22" minimum? 24" minimum? (This is a performance-only question-- the track will be hidden)
I should probably mention that I have large steam 2-10-0, six-axle diesels, etc-- large locos.
For a long coal train, if the cars are weighted properly, I would think you could go around a well-laid 22-24" R curve OK. For passenger cars, those with talgo truck/couplers they can do 22"R OK, if you want to use body-mounted couplers and diaphragms you’re probably looking at 28-30"R as a minimum.
Even most big steam engines today can do pretty sharp curves, a BLI 2-10-4 is recommended for a 24"R but can do 22"R with a little complaining. The thing you need to test though is if there’s so much overhang like on a large diesel that the engine can’t stay coupled to the cars, especially if doing passenger cars (like an E unit and 85’ cars).
Hmm-- so I’m probably looking at 5 feet plus a smidge of space dedicated to it. I guess that’s doable. Since the aisle space adjacent to it would be an entrance, people might just have to turn sideways and huff it in to get in. After that though it would open up and be comfortable.
A 30-inch curve you wouldn’t even necessarily need to hide.
I have the space everywhere else. This is the one place that is going to bulge out into the part of the room I’m trying to protect. I’m doing my best to think up a way I can either make it happen somewhere else or as minimally as possible. In the end it may just be reality and I have to live with it.
My advice is always to mock it up and test it with your ‘stuff’. Despite the claims from a manufacturer, a perfectly running engine of one type may still be an oddball and want another 1" of radius over the minimums of its type. Some assembly variances mean that one coupler will swing fully while another will impact an appliance slung under the frame of a passenger car. Your best bet is to see what you own and run can really do.
That aside, a couple more points. A 2-10-0 is not considered, generally, to be a large steamer. They were about the same size as a light Mikado 2-8-2. The Bachmann Decapod is good for tight radii down to 18" AFAIK.
Secondly, I feel that hidden trackage should be given as much, or more, care than what you can see and reach handily. I would go wide on separations so that clearances were generous along curves, particularly tight ones, and I would work hard at keeping my curves upward of 26".
FWIW, all the Walthers passenger cars I have will go around a 22" radius at reasonable speed. Anything less and the couplers get unhappy. The Bachmann passenger cars have articulated couplers and will do sharper radaii. I don’t have anyone elses stuff yet so can’t comment on Kato or Rapido. I use DL-109’s and they have a fair bit of overhang but no issues on 22" radius. As mentioned elsewhere the overhang and fouling of adjacent cars or scenery is probably as big an issue as minimum radius. Hope that helps. J.R.
Yeah, all of that is good and sensible. Its just the location of the curve and future marital harmony If I eliminate it altogether I lose roughly 100 linear feet or so of mainline run (i.e. no peninsula). If I overdue it I’ll have to suffer the “glare of the railroad commission” from now until eternity… if you know what I mean [:)]
I’d get some Kato Unitrack or Bachmann EZ-Track and try it out on the floor first.
Remember that the 30"R for passenger cars really applies only if you want body mounted couplers and diaphragms. IHC, Rivarossi etc. passenger cars with truck mounted :talgo" couplers will go around 22" or even 18" R curves - even the 80-85’ long ones.
If you’re going to be running Walther’s full-length passenger cars, I would say that 24" is going to be your ABSOLUTE minimum, and only after you’ve fine-tuned the cars like a grand piano. Personally, as to what you state you’ll be running, I wouldn’t go with anything less than 30".
My own absolute miniumum on my layout is 34" radius, and only in a few spots. For the most part, my minimum radius is 36", and even with those fairly generous curves, I’ve had to ‘tune’ those Walthers passenger cars like crazy. As another poster suggested in another forum topic about them, those cars are definitely not RTR out of the box–they take some major ‘tweaking’ in some instances to get them running at top performance.
first it is not the number of drivers on a locomotive that counts so much as the length of rigid wheel base. that is to say that with adequate side clearance, a large drivered 4-8-4 will need a broader radius that a small drivered 2-10-2 because the wheelbase is longer.
second is if you are hand laying track consider a slightly wider gauge for tight curves. the prototype railroads did this sometimes.
and last, spiral easements will let you get away with a sharper radius in the main body of the curve. the main problem area is where tangent transitions to curve because the end of the car on the curve “kicks” out of the track center line while the one on the tangent still has the coupler in the center of the track gauge. this can be a bigger deal than you think, especially with body mounted couplers on long cars and on passenger equipment with diaphragms.
i had to prove this to myself and found that a 30" curve with easements was preferable to a 36" without.
I might be able to get away with a 30-inch radius curve there. Its gonna cause the end to balloon out though and I’ll have to either eat it all on the aisle side or else try to straddle it on both sides. As I indicated earlier, its not a matter of physical space. The room is around 17 feet wide at that point. But it eats into the part of the room my wife wants, and of course I have to leave room to walk through that takes into consideration two growing youngsters.
Let’s say I ran a full-size passenger train arond the curve (meaning 85-foot cars) at a restricted speed, is there a difference in the opinion? Or is it just simply too tight / etc for close-coupled cars to negotiate?
(and I did read up on the NMRA RP11 as was suggested)
I’ve noticed in MR articles since the late 1970’s that 30-inch minimum curves had become somewhat of a standard minimum in HO. The original poster was asking for mechanically reliable curve minimums for cars up to 85’ long. Manufacturers recommend 24-inch minimums for cars like Walthers, but its always a good idea to add a little onto that so you aren’t living at the edge of reliability. Therefore I’ll have to agree, go with more than that - at least 28-inches in HO and 30 is better.
Hi!
During construction of my HO layout over the last few months I’ve asked similar questions to yours, mainly applied against the lower staging level of the 11x15 layout and its 2 percent incline to the main level. Here is what I came up with, and it’s been tested, tested, tested with the goal of ZERO derailments (which I’m finally satisfied I’ve achieved - barring operator error of course).
I have 4 freight staging tracks, that wind around a corner. The inside curve is 24 inch, and is the minimum I would consider for long trains. Of course the curves all have easements, joints are soldered, and turnouts “tuned”, etc.
There are 2 passenger sidings that also curve around a corner, and the minimum radius of the smallest is 26 inch. I’m running all Walthers cars, and they run beautifully. I could go to 24 inch with relative safety, but I want that extra insurance.
During my testing, the biggest “problem finder” was my two BLI 10 drivered locos (2-10-2, 2-10-4). If you have a potential problem, they will find it.
Also, none of the above means a hill of beans if your cars/locos aren’t “lubed and tuned”, especially for free rolling wheelsets, proper weights, and coupler heights.
If I eliminate it altogether I lose roughly 100 linear feet or so of mainline run (i.e. no peninsula). If I overdue it I’ll have to suffer the “glare of the railroad commission” from now until eternity… if you know what I mean [:)]