I model HO and I just don’t have the space to have a minimum of 30" radius, that takes away so much straight away. Although 30" is far too sharp a curve when translated into real life railroads, I provides enough clearance for most long non-articulated steam engines (excluding brass). The longer rolling stock, for instance the Walthers 10-5 sleepers handle these curves with little to no overhang. On my new layout that I am building I think 30" should be the maximum. (Orignally I planned to do a double loop with 34" and 36" curves, but a 14ft long table just isn’t meant to loose so much straigh away.)
Now, take Dave Vollmer’s N scale layout as an example, I don’t know what radius he uses for N, but they don’t look ridiculously wide, quite modest curves actually, if I could translate this into HO, not sure how, that would be helpful.
I’ve been watching several modular layouts on Youtube for HO (my new layout is similar to a modular donut shaped layout, only considerably smaller), and one in particular has rather large steamers like the M1a or larger running on 22" radius. I’ve tried this myself, however, I wasn’t pleased with the results, my BlueLine J1 2-10-4 accepted them (still not a pretty sight), but my C&O T1 wouldn’t budge, infact it would still tend to jump the tracks even on 30".
Most passenger cars that I get like Walthers say a minimum of 24", so I would assume that most large steamers should use this as the minimum.
I forgot what Selector uses for general radii, do any of you have suggestions for my predicament?
compromising on the minimum radius may lead to a lot of frustration, when you can´t run your locos without problems. Your minimum radius is finally determined by your locos and your rolling stock. There is a formula to calculate your minimum radius based on the lenght of the cars which you plan to operate on your layout - IIRC, it was 4 times the lenght of your longest car.
The info at the LDSIG link Stein posted is very helpful, as it explains what to expect at different radii vs. just a blanket “thou shalt not”.
Though I don’t have direct experience to help you (yet), using the LDSIG rule helped me make a similar decision. I have a minimum mainline radius of 24", yet I still plan on running Amtrak trains. Since my 24" curves are all hidden, toy-like appearance is a non-issue. I know I will be “pushing it” in terms of tracking, but my expectations are set and I won’t be bitterly disappointed if it doesn’t work out.
If you can fit in 26in or 28in curves even in hidden areas do it. You really need to try the curves out with your rolling stock. Walthers 20th Century Observation car is claimed to work on 24in but a flaw in the model results in derailing at under 32in (a rear step interferes with the truck).
General comment on curve radius: just how many of us have the space for 36in radius curves in HO?
the LDSIG calls a 1:3 ratio toy-like, an 1:2 ratio pushing towards technical limits. Your Amtrack coaches are one foot long so your 24" radius has 1:2 ratio.
I have posted the table many times, never intended to force someone. Only difference was the comment; the 1:3 ratio is the compromise most of us have to live with. If I remember well this was a John Armstrong statement.
My experience over 50 years learned me, pulling over a curve with a ratio like yours (1:2), can be done without much tinkering; but try to push a string of these coaches. BTW Andy Sperandeo applies in 102 Realistic Trackplans a 1:2.5 ratio; so he feels a 30" radius would be appropriate.
To my taste you are pushing your luck a bit, keep smiling and having fun.
Paul - I was thinking of the NMRA RP-11 table with my above statement and not any feedback you’ve given. The NMRA table gives readers more of a yes/no feel, IMHO, than the LDSIG page.
I know I’ll be on the edge with those coaches. But passenger service is not a make-or-break druther for my layout, so if it doesn’t work out - “No Big”, as my 12 year old daugher would say [:)]
That’s the kind of call the OP will have to make on shrinking the radii vs his druthers.
I can definately tell you walthers heavyweights (at least the 14 section and the solarium observation) do NOT work on the advertized 24" radius. Not even with easments. You will have to trim the center sill.
Bachman spectrum P70 cars work fine, and Centrailia PRR P85s work too.
I have 24" with 1" in 16" easmants and the easments go a long way towards helping with long wheelbase ops.
I’m currently building a helix, and the “straight and hard” 24" radius is much less forgiving.
I can hear the plasic creaking on my BLI J1 2-10-4, which does just fine on the eased 24". You can also tell it’s putting up with additional drag, but it does go.
I have a brass N2 2-10-2 that works OK on the eased 24, but can’t handle the hard 24 helix.
My M1 4-8-2s work great on the eased curves, and tolerate the helix quite well.
I did testing for the helix by laying out first a full circle of 24" radius on two sheets of paneling out on the back porch. This will settle all questions about what will and what won’t go.
After that I laid out circles of 25, 26, 27 and 28.
Even at 28 the 2-10-2 had severe difficulty, and the increase didn’t make that much difference on the 2-10-4 or the walthers cars, so in the interest of keeping another desired feature (a loop track outside the helix on the lower level, and a gentler S curve coming off the helix), I went back to 24 to save space.
My mainline is 40" radius or greater except for one 180 degree curve that is about 29" radius. It was all that I could fit and fortunately was the location of a tight (10 degree) prototype curve. It operates fine with everything I’ve run on it including brass passenger cars (I have no brass engines). I have a 24" radius wye that I have run Walthers passenger cars through without problems although they don’t look too good. I’d be surprised if you had operational problems on a 24" curve with any current mass produced HO models if the curve is truly circular and relatively flat. Some brass might have issues. Nothing but maybe ore cars will look good on 24" radius in my opinion.
For appearance it makes a big difference whether you are viewing from he inside or outside of the curve. That 29" radius curve is viewed from the inside and in my opinion looks about that same with a 80’ passenger car as a 40" radius curve viewed from the outside.
I went through much the same thought process. I have a double track main line and (ultimately) wound up using radii of 24" and 26.5" for the inner and outer tracks respectively. I really wanted 30" minimum radius on the mainline but just could not fit such wide curves. I have documented my design process in my blog (see sig below).
Trains run fine on my layout now but I should note that maximum car length is 50’. Even my C44-9 seems to have no problem on the 24" curves. On the whole however, I now have some regrets that I did not investigate N scale more seriously. N scale might have worked very well for me since I don’t really plan much switching anyway.
While most approach their layout planning with minimum radius in the forefront, I think that we might be better -served by starting with the maximum and using it wherever possible. The minimum will rear its ugly head eventually, but perhaps in a way that will affect only a small portion of the layout.
Maximum radius is, in part, determined by the style of layout: an island-type layout built in the centre of a 10’x10’ room will have a maximum size of 6’x6’, leaving aisles of 2’ on all sides, although aisle widths of 3’ would be more practical for most. The 6’x6’ layout would likely require access hatches, as a 3’ “reach” is pushing the limits for most people. Such an island layout could also be pushed into one corner of the room: its size could expand to 7’x7’, allowing for 3’ aisles on two sides. Again access holes would be required. On the 6’x6’ layout, your maximum radius would probably be around 34" or 35", giving you a maximum mainline run (once around the perimeter) of about 18’ and the 7’x7’ version would give you a maximum allowable radius of perhaps 40" or 41" and a mainline run of almost 22’. Not too bad. [;)]
The main benefit of such a layout is the ability to create"deep" scenery (as long as you can reach to build it).
The drawbacks, however, are the access holes - not much of a problem when you’re young and flexible, but you won’t always be so. [:O] Another drawback of these layouts, especially the ones pushed into a corner, is that for almost half of your mainline run, the train will not be up front where you can enjoy it visually. Likewise for your scenery, and you’ll have to motorise all of your turnouts which are beyond your reach. Your trains, where they’re readily observeable, will be seen from the outside of all curves, accentuating the size of the gaps between locos and rolling stock - moreso as length of the equipment increases.
In the same 10’x10’ room, you could build an around-t
Working on the basis of, “An ounce of experiment is worth ten tons of opinion,” when faced with your dilemma, I built a test spiral of flex track temporarily tacked to a sheet of 1.5 inch foam with straightened paperclips. After transitioning to a nice wide ‘overmax’ radius with a spiral easement from a tangent, the curve radius was reduced 50mm every 30 degrees down to 300mm (<12 inches.) Then I connected a pair of test leads and ran all of my locomotives and long rolling stock into the spiral until they became actively unhappy. By backing off 50mm, I established the minimum radius for each piece of MY rolling stock.
The only item which might be of interest was that my 16.5mm gauge Mantua/Uintah 2-6-6-2T actually rounded that 300mm radius with all wheels on the rails and the drive not quite binding! That matches the design capability of the prototype, which was designed for 68 degree curves. (All of my other rolling stock is 1:80 scale Japanese prototype, so its performance is not applicable to American HO practice.)
From what i have found out with my 5’ by 19’ is that the six wheel car
trucks seem to be pushing the limit on HO 18" curves. Same goes for the six wheel loco trucks. My SD7 will make the curves but the track has to be very true. I have curves from 18" to 24" recommend you make them as large as possibly.