What minimum HO scale radius do you recommend? I know that it depends on what cars you are planning to run. Let’s say I want to run Walthers Amtrak Superliners, 89’ Tri Level Enclosed Auto Carriers and things like that. Please let me know what you think.
On easily accessible track, somewhere between 22-24" is doable reliably if you do it right…with easements to keep your insurance paid up. For largely inaccessible, or hidden track, you would want something closer to 24-26", also very carefully laid and proven in both directions, pulling and shoving.
For complete ease of mind in hard-to-reach track, or track that is hidden, I would try hard to squeeze a 28" curve into that spot.
This is my recommendation for the car lengths you describe.
-Crandell
For super liners I would use 24 inch or bigger. They will look silly on anything smaller. 50 foot box cars on the other hand will take 18 inch turns, again a little silly looking but with proper weight and free rolling truck’s they will track well.
Bigger is better if you have the room.
Cuda Ken
Three times the car length: http://macrodyn.com/ldsig/wiki/index.php?title=Curve_radius_rule-of-thumb
89’ Autoracks and you guys are recommending 24" radius?
For equipment that large, absolutely go with the 3 times rule…or 3 times the length of the car for the radius. Atleast 30"…not for looks, but for operation.
David B
hi David
If I remember well John Armstrong covered theis subject some years ago. I liked the words he used.
1 : 2 tight (#5 switches)
1 : 2,5 moderate, most of us have to live with (#6 sw)
1 : 3 broad (#7 sw)
1 : 4 deluxe, for those with more space then druthers. (#8 sw)
For easy coupling you’ll need a 1 : 5 ratio. (and a higher numbered switch when used in a crossover)
Paul
The best way is to actually test them. They might be easily modified to go reliably around curves less than the 3-times rule. If you are intending to run them at fairly close to prototypical scale speeds, more is always better. For that length, say at 60-80 smph, probably 36" would be ideal, but not strictly necessary; again, the proof is in a mock-up test.
Heavyweight passenger cars made by Walthers are a scale 80’ long, and they have the diaphragm shrouds between the cars. Their recommended minimum radius is 24", far below the 3-times rule. Some users report poor results at the stated minimums, while others say they routinely run theirs on 22-23" curves with next to no alterations…just some truck and coupler tuning on the very same product.
My own heavyweights, from both Spectrum and Walthers, are good at low speeds on my 24" minimums. Something a few feet longer in scale might do very nicely, sans diaphragms, on 24-26" radii…might. So, I would feel justified and comfortable recommending 28" if the tracks are properly laid.
-Crandell
Personally, after playing with these little trains for 40 years now, I have to say I use the 3x rule as a BARE minimum for good operation.
As for looks I like 4x or 5x the longest car/loco.
These are not toys an 8 year old plays with under the Christmas Tree, they are operating models. We should try to at least get close to a radius that is prototypical.
But what do I know, I’m just a hick with a pickup, a gun and a few model trains.
Sheldon
One additional note - I build all my passenger cars with working diaphragms that touch and are nearly scale close coupled. I find the gaps between the diaphragms of products like the newer Walthers passenger cars totaly unacceptable.
I also use short shank couplers on some freight cars that have their coupler boxes too far out, again to get more correct spacing.
Same with diesel loco lashups, no gaps between diaphragms if so equiped.
So my recommendations for curves are based on my standards for these items.
For me these appearance standards are a must have.
Sheldon
I recommend 48" radius and #10 switches. Industrial trackage can get a lot smaller, down to 24" or even smaller, but not for the 89’ cars. Your trains will look very nice on these curves and they should operate nicely too.
I have a simple test track layout under construction to these standards, and I am very happy with how it’s turning out. I’ll note that there will be a bit of 36" that will represent a branch line connection and a freight-only yard that uses #6 switches. The main yard has 3 tracks also with #10 switches and 48" minimum radius–the curves are actually larger, as they wrap the outside of the mainline.
Ed
I would say the minimum for that would be 30", but personally I would try for 36" to 40".
I thought your track layout was already done.
Also how did you get from the California Zephyr (1940s) to modern 89’ auto carriers?
I built 18" radii and then received for Christmas a 484 steam loco, which will not run on these tight curves. I wanted to bawl.
I try to use a 3X (NMRA) standard for my N-Scale layouts but sometimes those 3X/4X formulas are just a little beyond our layout parameters – 3X says 37"; 4X says 49" – but I don’t think I would try operation of cars of this length on anything short of 30" – 2.5X – with easement curves.
As an aside awhile back – I don’t remember exactly how long ago it was – you posted some photographs of your roadbed; I was very impressed and I sure would like some more photos showing your layout progress since then.
the largest you can get away with. large radius curves with easments will pay off later and you will be glad you did it. even short wheel based equipment looks and operates better on big curves.
i don’t know how long your straightaways are but using, say, 30" instead of 24" curves will only cost you a couple of 40’ car lengths on the straight run.
spiral easements pay off with any radius curve. the trains seem to flow in and out of the curve instead of the “quick-make a left” appearance of the old lionel displays in the department store windows.
grizlump
Good point about easements, I forgot to mention that earlier, but all my curves have spiral easements or are laid out as parabloic curves making them just two giant easements back to back.
Paul Mallery made the argument for larger curve standards years ago and it fell on mostly deaf ears. I suspect it is a little better now but many are still content to run 85’ cars on 30" curves and don’t see the problem.
Sheldon
I would ask a different question, What size aisles do you want? People reccomending 22-24" curves must be verY skinny since a 180 degree curve is 4’. Yeah you can do it but when full length cars started coming out in the late 60’s even then the minimum radius reccomended was 30". A much better plan is to draw the room and try to fit in the biggest curves you can. After forty years in the hobby and finally a full basement to work with my minimum mainline radius will be 48" and most will be 60" or bigger. My standards have gotten bigger on every railroad built since I started in the hobby. You can never make a curve to big but you can make ot too small in a heartbeat.