Hi all, I probably should post this in layout design, but I figured that since it is an HO specific question, I would post it here and give it a shot. So, my question is what is the absolute MINIMUM turn radius I can get away with in HO using 6 axle diesels such as SD70s and Dash 9s? The turns will be covered up in tunnels and such so it doesn't really matter if it looks funky going around the curves. My only concern is getting it to fit into a tight space. I have been fighting with this for a while and if I can possibly get away with a 15 or 16" radius it would make designing my new layout a LOT simpler. Please let me know as I am anxious to get to planning!!
There's no way you're going to get an SD70 or -9 to go around 15 or 16 inch radius. You MIGHT get one to go around 18 inch radius but I doubt it. The minimum radius in my experience would 22 inch ant that may be pushing it.
Brian, Jeffrey is right. Another consideration: Laying a tight curve inside of a tunnel is asking for problems, but the problem can be somewhat eased if you have easy access to retrieve derailed locos and cars that you attempt to run over 'tweeked' roadway. I hope you find a solution, friend.
Another consideration is the type of cars you have to run with. A model of an 89' Boxcar on a 18" curve will make the couplers almost hang out beyond the outside rail of the curve, anything less than a 50' car would be pulled off the rails every time. If you do go with the 18" curve I would put some serious thought into only running 40-50' cars and 4 axle locomotives... that would cut down on your headaches. Even the 1:1 scale railroads have car length and locomotive size restrictions due to curves, clearance issues, decaying timber bridges, etc...
I concur with Jeffrey - anything less than a 22 inch radius in HO will not work well with six-axle locomotives and is almost impossible for 89ft cars with fixed couplers. I had one curve off the mainline that was 18 inches and caused nothing but problems; once I relaid that section with a 22-inch radius, I've had no difficulties since.
What about a test track? When I started with H0n3 I've made a test track with different radii. Wolfgang
...if I can possibly get away with a 15 or 16" radius it would make designing my new layout a LOT simpler.... Actually it won't. It will make you think you can but it will lead you down the harder path trying to make it work, only rip it all out and start over. There was a very good read in the 1st issue of MRH - Jan 2009 - on track radius for all scales. You can down load it for free, all issues are free, here http://model-railroad-hobbyist.com/magazine/back-issues Also, try what Wolfgang said and use a test track. Don't just do a short section but mock up a good test section to include curves, straight sections, switches and see how the train acts going from one to the other Steve
Brian, my first layout incorporated 18" curves on it's inner loop and 22" on the outer. "If I knew then what I know now" I never would have done it. If you're never going above 4 axle locos and 40' rolling stock it's fine, but if you want to go 6 axle and modern rolling stock and passenger cars, I'd never go below 22". Yes it seems like the answer to a lot of layout issues to go to 18" and tighter, but in the long run I think you'll regret it.
Thanks for all the info guys! I think I am either going to have to figure out how to get a 22" curve on this and fit it into my room or just make a shelf switching layout and be happy with it. If I had the big bedroom that my girlfriend uses as her hobby room I would have plenty of space to do everything I would like to and more, but as it is I will just have to wait I suppose. Its either that or find someone who wants to buy a 4x8 N scale layout! LOL
