' I'm Radii Crazy!!!!

[TrainsRMe1]

 Hey Fellow Mrxrder's

    I have a question, I'm running modern era equipment such as ac4400's mac'sd90's etc (six wheeled axled loco's. What would be the best radius I could run without the loco derailing and looking realistic. Note:( I have about 2 feet in width to work with here.) I have been goin' nutso trying to figure out the right deminsions Thanks for the help

                      Sincerely,

                                  TrainsRMe

[canazar]

Those are big engines...   I am sure you will get alot of different replies to this but here is some info to help you out.  I have some -9's, SD70 and AC4400s on my layout.

You can get away with maybe 20-22 depending on the maker.  They usually list operating minimums.   That wont look good at all but it will work.  

24" radius is OK.  Runs well, looks ok.

26-28 is great and still pratical.

 

When is doubt, get as much as you can.

[TrainsRMe1]

Thanks Canazar, I will give that a shot

[tstage]

Trains, 

If 4' is your maximum width then 22" will be your maximum radii.  Some 6-axle locomotives and longer, modern rolling stock should operate fine on that size curve.  However, they won't necessarily look good doing it.

If you plan on having opposing curves on your layout, make sure you separate them with a section of straight track that is as long as your longest piece of rolling stock or locomotive.   Otherwise, you create an "S" curve and run the risk of derailments.

Hope that helps...

Tom

[lvanhen]

re you in N or HO?  2' in N will allow 11" radius, not too bad, but is you could squeeze 30" or 36" it'd be better.  In HO you can't turn anything but a trolley in 2'!!  That'd be 11" - trollys can do about 9". 

[Last Chance]

I run 31 inches. Yes I take up more room but no worries on equiptment except the most largest of Brass engines built in the old ways.

[jimmylow]

Perfect timing. I have a hollow core door 87" x 25.5". I want to run P42, E8/9 and a bunch of Superliner and California Zephyr on it. The max radius I can squeeze is 12" with little room at the edge. My next compromise is either a 11.5" or 11".

Do you think I am risking too much with that 11" or max 12" radius and long modern equipment? Will there be serious overhang?

 

Jimmy

[HarryHotspur]

re you in N or HO?  2' in N will allow 11" radius, not too bad, but is you could squeeze 30" or 36" it'd be better.  In HO you can't turn anything but a trolley in 2'!!  That'd be 11" - trollys can do about 9". 

I have an HO test track with 10" radius curves and my NW2 runs fine on it, as do 0-4-0s and 0-6-0s. They look fine too. Lots of myths get perpetrated in this hobby.

[HarryHotspur]

re you in N or HO?  2' in N will allow 11" radius, not too bad, but is you could squeeze 30" or 36" it'd be better.  In HO you can't turn anything but a trolley in 2'!!  That'd be 11" - trollys can do about 9". 

I have an HO test track with 10" radius curves and my NW2 runs fine on it, as do 0-4-0s and 0-6-0s. They look fine too. Lots of myths get perpetrated in this hobby.

That would be one man's opinion.  Why don't you take a pic and let others make up their own mind?

Can you couple a car to your loco?  I imagine the couple overhang would be pushing its' operational limits. 

David B 

Of course it's one man's opinion. That's all anyone can have. And yes I can couple cars to the locos. But I'm not going to post a photo here just so the aloof ones can say, "See, I told you it would look bad."

I was replying to a guy who said nothing bigger than a trolley could negotiate 11" radius curves, and that simply is not true.

Nobody on this forum uses prototype sized curves. That being the case, it's up to the individual modeller to decide what looks right for him. I just threw in the comment, "They look fine" to save people the trouble of posting the standard next question, "Yeah, but how do they look."

As someone once said, "Beauty is in the eye of the beholder."

[CSXDixieLine]

I am also modelling modern equipment (including long intermodal flats and autoracks) in N-scale and  settled on a minimum radius of 15". What really helped me was to get a 4' x 8' sheet of homasote and mockup some temporary track arrangements with different radii from 11" up to 24". I then took lots of pictures and compared the results and decided that 15" looked really good. Note that I am trying to fit a layout in a limited space and am trying to find the smallest acceptable radius for that space. A better approach would be to find the largest radius that your space can accomodate, but this is not always possible. Jamie

[Autobus Prime]

re you in N or HO?  2' in N will allow 11" radius, not too bad, but is you could squeeze 30" or 36" it'd be better.  In HO you can't turn anything but a trolley in 2'!!  That'd be 11" - trollys can do about 9". 

I have an HO test track with 10" radius curves and my NW2 runs fine on it, as do 0-4-0s and 0-6-0s. They look fine too. Lots of myths get perpetrated in this hobby.

That would be one man's opinion.  Why don't you take a pic and let others make up their own mind?

Can you couple a car to your loco?  I imagine the couple overhang would be pushing its' operational limits. 

David B 

Of course it's one man's opinion. That's all anyone can have. And yes I can couple cars to the locos. But I'm not going to post a photo here just so the aloof ones can say, "See, I told you it would look bad."

I was replying to a guy who said nothing bigger than a trolley could negotiate 11" radius curves, and that simply is not true.

Nobody on this forum uses prototype sized curves. That being the case, it's up to the individual modeller to decide what looks right for him. I just threw in the comment, "They look fine" to save people the trouble of posting the standard next question, "Yeah, but how do they look."

As someone once said, "Beauty is in the eye of the beholder."

Folks:
If you bring the layout up closer to the eye of the beholder, sharp curves look better, as you can't judge the radius as easily.

There was a railroad in MR (or was it RMC) recently which used HO scale and curves this sharp. Locos were small 4 and 6 wheel switchers. There was once a lot of work being done in HO with very small curve radii of under 15"R, since HO was the reigning flea gauge back then. Generally, the equipment used on such layouts was small - the Dockside 0-4-0T was popular, and short ore cars, and old-time boxcars.

[lvanhen]

HarryHotsput,  You are obviously going to do whatever you want - if you don't want someone else's opion, don't ask.

[HarryHotspur]

HarryHotsput,  You are obviously going to do whatever you want - if you don't want someone else's opion, don't ask.

I didn't ask.

[HarryHotspur]

David, what is "my groups"?

How does one post a photo?

BTW, please keep in mind that what I have is a test track, not a layout. But on my next layout I'm gonna work in a section of 80" radius curve just so I can say I have it.

[dehusman]

I am a little discouraged that you wont back up your previous statement without a pic as I would like to see your switcher go around a 10" radius (as would many others). 

I have seen trolley layouts that have engines that are essentially the same drive as 4 axle diesel go around 10" or sharper curves.  What's the big deal?  Its not much of a challenge.

There are N scale "layouts" where the inside rail of the "loop" is a half dollar.

Dave H.

[Autobus Prime]

Of course it's one man's opinion. That's all anyone can have. And yes I can couple cars to the locos. But I'm not going to post a photo here just so the aloof ones can say, "See, I told you it would look bad."

I was replying to a guy who said nothing bigger than a trolley could negotiate 11" radius curves, and that simply is not true.

Nobody on this forum uses prototype sized curves. That being the case, it's up to the individual modeller to decide what looks right for him. I just threw in the comment, "They look fine" to save people the trouble of posting the standard next question, "Yeah, but how do they look."

As someone once said, "Beauty is in the eye of the beholder."

Again, you are trying to pass off your opinion as fact.  The fact is that there are layouts on these forums that actually use prototype size radius.  I for one do not, but they are out there.

For example, if someone has a switching layout and uses #10s as his switches, then he is well within the prototype.  Or, if someone is making a pier-based layout with tight radius, then, again he is well within prototype practice. 

My groups uses 80" min radius.  Again, well within prototype practice.

I am a little discouraged that you wont back up your previous statement without a pic as I would like to see your switcher go around a 10" radius (as would many others).   

David B

 

DB:

Well, he was not strictly correct in that one sentence then, although if he said "99% of modelers aren't using prototype sized Class 1 mainline radii" he'd probably be way on the safe side. But the rest of his points are worth repeating, I think..."don't dismiss, try" is one, and "rules are made to be broken" is another...at the very least, if you try and fail, you find out why the rules were made, yes?

[HarryHotspur]

David -

Did you know that at least one real railroad used 2-6-6-2 Mallets on track having curves with a radius equivalent to 15" in HO scale? I think it was the Uintah. 

[fwright]

I've said some of this before and I'll say it again.

The Layout Design Special Interest Group (LDSIG) has the following rule of thumb:  for reliable operation with detailed rolling stock using body-mounted couplers and NMRA wheel and track standards, the minimum radius should be 3 times the length of the longest car.  This is a conservative rule of thumb until you start using fine scale or proto wheels and track to match - then the recommendation isn't so conservative.

With NMRA wheels and track, you can normally push a minmum radius of 2.5 times the car length.  But there will be occasional models that won't work without some modification.  The tighter the radius in proportion to car length, the more likely the model is to need modifications to make it on the curves.

At the known extreme is Lionel and other O27 equipment - it typically runs on radii in the range of 1.1 or 1.2 times the length of the car.  To accomplish this extreme, some or all of the following steps are taken:

• underbody detail is eliminated.
• body is raised upon trucks so that trucks can swivel without striking any obstacles on the car
• truck mounted couplers are used
• speeds must be kept slow so that cars/locomotives don't tip over to the outside on the curves
• string lining (tipping over to the inside of cars in the middle/beginning of a train) with any but short trains is a constant problem
• a testing program is needed to weed out or modify rolling stock that won't make the curves as is
• larger than standard clearances are needed between parallel tracks on curves, and between scenic objects and track on curves.
• coupler swing may have to be enlarged beyond stock
• coupling distance between cars has to be enlarged beyond scale

In scale trains, as you tighten down to radii 2 times the length of rolling stock or smaller, some or all of the above steps become essential for reliable operation.  In HO, a 40ft box car is 6" long.  So as one progresses in radii to 12" or smaller, limited under body detail and truck mounted couplers become the order of the day.

The NMRA has recommended curve radii based on type of equipment that generally comes out slightly bigger than 3 times longest car length.

my thoughts, your choices

Fred W

[CSXDixieLine]

Although looks are important, I do agree with the post above that basically describes the performance problems you will have with a radius that may not look "too small." For example, I have an oval constructed of 11" radius track in n-scale, and there is no way any of my larger Kato locos can pull any cars without adding an extended coupler (which really does not look good). Otherwise the loco swings the front of the car right off the track--every time. These same cars do work just fine on my 15" radius curves. Jamie

[HarryHotspur]

Hey David -

How about posting a few pictures of your layout showing those 80" radius curves? 

[HarryHotspur]

Hey David -

How about posting a few pictures of your layout showing those 80" radius curves? 

Where did I say I have 80" curves on my home layout? 

David B 

Ah ha! So you don't have 80" curves on your home layout? Do you know anyone who does? If so, could you post a picture of their layouts? 

BTW, are you in N scale? 

[cuyama]

It's a fact of life that on Internet forums some folks just want to stir up a ruckus. Whether the information they post is broadly useful or not is beside the point to them. That goes for more than one poster on this thread, as it happens.

That said, it's important to recognize that there is a practical difference between pulling a few cars around a test loop and reliably pushing and pulling cars of a variety of prototype lengths around tight curves and through turnouts (as one does in operating a real layout). Fred Wright's thoughtful post describing the suggested practices from the LDSIG pages provides a good place to start.

Since the original poster noted that he was interested in large, modern equipment, arguing that smaller, older equipment will go around a small radius in HO (whatever radius that might be) seems beside the point.

[HarryHotspur]

Since the original poster noted that he was interested in large, modern equipment, arguing that smaller, older equipment will go around a small radius in HO (whatever radius that might be)seems beside the point.

Actually, it's educational. It took me a while to learn that the conventional wisdom in this hobby is not always correct. That knowledge, in turn, enabled me to build my first layout because I had no interest in a switching or point to point layout. And I'm confident that many other newcomers as well as some old timers feel the same way.

This is especially true if you and your son are building his first layout. So it could be beneficial to many a father to know that he can use (in HO) 15" radius snap track and run 4 axle diesels and most freight cars just fine.

And for what it's worth, I can reliably push and pull cars of prototype lengths arfor the era I model around 10" curves and through turnouts at almost full speed.

OTOH, if this forum is intended for advanced modellers only, I will quit trying to help newcomers. 

As a final note, I think some people take this stuff way too seriously. A hobby is supposed to be fun. 

[tstage]

David and HH,

Can you fellas take this "discussion" offline so as not to hijack the thread?  Thanks.

Tom

[rolleiman]

David and HH,

Can you fellas take this "discussion" offline so as not to hijack the thread?  Thanks.

Tom

They already have..

I could have missed it but I don't think the OP ever stated whether he was using HO, or N scale.