I am designing a new HO Scale layout. Is there much difference in the equipment that I can use if I go with 24" radius curves vs. 22"? Are there any guides about the car length that can pass safely through different radius curves?
from my expirence i notice that almost all locos pass the 22" radius without any problems almost all diesel locos would i would think, but you may have some problems with the large steam locomotives. And the larger passenger cars should pass 22" radius. But the larger the radius the easier it is on the locomotives and cars, trucks and wheels themselves, there wont be as much ware, and it would look a littel more realistic, I myself am going to use 22" radius
And another thing you can do to figure this out is figure out what the largest piece of equipment your ever going to use and then search it on the web and find its radius it can handel.
Most anything will run on 22" curves readily (just watch the overhang),
( taken from Bowser’s website for the Big Boy:)
Engine Overhang:
18"Radius Curve 1.688"
20"Radius Curve 1.437"
22"Radius Curve 1.375"
24"Radius Curve 1.250"
Even the “big steam” can take the tighter (20" or less) radii, although it will likely need some form of an easement into it (ie don’t go from straight to 18" curves and expect your 4000 class to stay on the rails - rather ease in from 22" or larger).
As such, using 22" radius curves would be more than enough for most locos and rolling stock, with the exceptions being only the largest of your equipment, but even then, you would probably be able to fudge it a little with easements.
Unless you are 100% certain to never introduce a brass 8-coupled steamer or bigger to your layout, you should be fine. Most brass locos of that size are not likely to run on curves under 26" due to their construction, but the less expensive popular steamers have drivers that are either blind or can move laterally by 1/16"-1/8", or thereabouts. This permits negotiating curves as low as 18" on many of them.
The BLI 2-10-4 models are advertized as needing 24" curves, but they will do bad trackage speed on 22" curves…sort of. BLI’s 4-8-4’s will do okay on 22" track, but it will have to be very well laid…very smooth, with good quality turnouts of #5.5 or higher.
As a gentle word of caution, having gone through it meself, most of us will soon want new steamers that tend to be larger and more beefy. Suddenly, your layout becomes more a liability than the pleasure it first was, and then the hobby becomes even more expensive and time consuming as you enter into the process of designing and building anew. Since you are already at an early stage, may I suggest that you be very practical and do all you can to try to delay this tendency to the extent possible? Plan now, if you can, for the desire for bigger curves and enjoy the bigger steamers when they come. If you can manage 24", or better, 28", you will have essentially guaranteed that you have room to grow.
I realize, though, that you have asked the question of keeping your curves smaller, not larger, so my suggestion may not be entirely welcome…I am sorry if that is the case.
You might want to take a look at:
http://www.nmra.org/standards/s-8.html
This is the Track Centers Standard of the NMRA.
I’ve had experience with 22" and 18", and while most diesels run on 18, definetly go with 22". One other thing, are you using flex track or sectional track?