Scale and how much space does a half circle really take up?


S

StrasburgNut

Pennsy Area rail fan
Hi All! I have been lurking for a while taking in a ton of information so I can get back into Model Railroading. So I need to post a question (first post by the way) I cannot find the answer too.

Before I ask, here is what I want to do. I have a 13' by 6' room in my basement that I will be converting into my model railroad empire. I would like to have layout like a dogbone, cut in half lengthwise, and on it a mainline that runs on it and some switching too.

I have some N scale already, but am not opposed to switching to HO.
So the real questions:

1.) Is N scale easy to work with? I'd like to run a long train or two on the mainline with a nice size yard to switch around in. I hear that you need to be perfect in putting down the track, or else there will be a lot of derailments.

2.) I am trying to correlate the radius dimensions with the width in feet. I am thinking of depth of 30 inches for all three side of the layout. What radius curve can I fit in there comfortably and run most equipment? I am pretty sure I can fit the broad radius cuves for N scale in 30 inches, but what about HO?

Any further help would be greatly appreciated. Especially in terms of what are the pros and cons of HO and N scales, and what is readily available for each.

Also, what type of track does everyone use? I see the snap track out there, and I was wondering how good it really is.

Thanks in advance for your help!
 
well if you run a 30" radius for HO or N you are doing good. HO scale would be better at 36 or more but 30 is still good for all rolling stock up to 50ft cars but passenger cars or 86ft frieght cars may not look good or be good if you plan on running them on 30"r.
 
Alcomotive,

Thanks for the reply. I am looking for a small scale operation. A Pennsylvania RR and a fictional town hybrid layout. Basically a few industries sustaining a local town and vice versa. Maybe a small, local switching hub for a local mainline railroad. So I would be looking for smaller cars.

So what width in feet would a 30" radius in ho take up? I am still very confused on this concept. :confused:

If I could create a more realistic looking line in N, I would go that way. If I could do it in HO, I would like to do that as well because of there is more available for HO (or am I wrong?)
 
Radius is half of the diameter. If you have a 30inch raduis, then you have a 60" diameter. I also believe that you need a little more room than the diameter of the track so you're not running right on the edge. If you have thirty inches to work with, you could use 12.5 inch radius track in N scale. That would leave you with 2.5 inches on each edge for clearance.
 
You're getting messed up with how to calculate a radius. The easiest way to do this is remember that the radius is half a circle, which you need to complete a track loop, even if it's just the top half of a circle. Assuming that 30" is the biggest area you have, the biggest radius track you can use is about 15" in HO. It will still be a 15" radius in N but the curvature will be about half of HO. A 15" radius curve is extremely sharp in HO and will really limit you to things like small switchers and short freight cars. If 30" is all the space you can get then N scale is what you need to use for any kind of decent operations.
 
Thanks for all the input. :)

Can someone explain the limitations of car lengths to curves?

Also, being this will be a long layout, do you recommend flex track or the ez track?

Should I used the insulation board underneath?

Just some newbie questions.:eek:
 
I figured my max radius would be about 20-22" for my outside mainline.

What's the smallest radius I can go and still fit road switchers and maybe an occasional 6 axle diesel? I'm thinking 6" would be the absolute smallest....


(N scale, keep in mind)
 
There's a nice little little degrees of curvature chart in multiple scales at http://urbaneagle.com/data/deg-curve.txt. If you think of degrees of curvature, .05 degrees is barely noticeable as a curve while 90 degrees is basically a square corner. Most mainlines try to keep curves to no more than 5degrees. As you can see from the chart, that would require a table width of over seven feet so that's not going to work for you. If we look down the chart, we see that 28 inches (so you don't go all the way to the end of the layout) gives you just about a 15 degree curve in N scale. Not as good as the real thing but still a pretty broad curve. A common size in N scale for a 15 degree curve is 315 mm or 12 3/8". That should allow you to operate anything but the very largest articulated locomotives.

Using pink or blue styrofoam gives you lots of scenic possibilities so I would certainly use it.

Have you ever laid track before? If not, the e-z track will be much easier to lay. If you have laid track before, use the flex track. It's cheaper and you reduce the number of joints so it's more electrically reliable. The downside to laying flex track is it's an art and, if it's not done right, you get the Toonerville Trolley effect instead of a nice smooth track like you want. :)
 
yeah, I've got foam layed down already, and thicker on my industry side so I can have a grade as I want.

My outside main is going to be obviously a larger radius than the inside main, but I'm thinking of doing a small internal loop or tight 'u' turn for a switch to a mine site on my railfan side....I doubt I can fit it in, so I won't bother right now.

I'm not great with flextrack, but I'll be reading up on it and once I get my grade laid down with foam (is that the best way, by the way?) and some roadbed down for the outside main, I'll start laying that track and going from there, working my way along with switches and what not.

I know it's going to take some time, but with DCC I'd rather not have electrical issues, and having flex just makes for smoother operations in general.


I wish I could say I was going after a specific part of the U.S. or subdivision of xx railroad, but at this point I'm just doing a layout where I can have some switching and scenery. I'll have mostly UP and ATSF/BNSF locos, but i got a great deal on a conrail dash the other night, so that could be a leased unit (ya think? heh). More or less just stuff I wanna play with, I guess :D
 
Oh, I just realized that you are spliting the layout down the middle. You can probably get away with 30 inch radius for your outside main. That would be huge in n scale.
 
So, with a 30" radius, I am pretty sure I can run all equipment. I think I saw in a book that 16" radius curves in N scale are considered "broad". But if I go the next dimension down to "conventional", how much in terms of limitations am I putting upon myself? In terms of locs and rolling stock? Longer cars I would presume, Amtrak Silverliner type cars?
 
I'm not the most knowledgable person when it comes to N scale, or HO for that matter! I do know that using 30 inch radius curves in N is almost the same as using 60 inch in HO. Most people on here consider 36 inch curves in HO to be a good size radius. With that size, you can run almost anything without too many problems. This is one of those, 'bigger is better' things. I don't know the N scale equivilant to have broad enough curves to run anything you want. If you are having a 'railfan' side of your layout, I would make the curves as broad as possible. Your yard side could use smaller cuves in order to fit more yard space and operations. Being able to alter the radius of a curve mid curve is an advantage of flex track. It would be a little harder to do with sectional track. Hope I helped a little.
 
If your space is 30 inches deep, you can't go with 30 inch radius crves without running right to the edge of the layout. That's why I suggested a 28 inch radius, to give your both space for scenery and some safety when a train inevitably derails right where you have the least clearance between the track and the floor. Trust me, I know about this phenomena. :)

You can easily decrease your radius to 24" and still run anything made in N scale. It won't look quite as good but it will still be functioning just as well.

I'm not sure what you mean by using foam for roadbed. Do you mean using the pink or blue foam you already have laid as a sheet on the layout? If so, that's not the best way to create a good grade profile. I'd use either cork or Woodland Scenics black roadbed so it will look more prototypical when you ballast.
 
no, my table width is 48", so doing anything more than 22" radius wouldn't fit on the table.

Foam I'd use as the base for the grade, but yeah I have roadbed in the mail to me now for track.
 
OK, somehow I'm getting dimensions mixed up. If your available space is 48" then a 22" radius is your maximum. That still a nice sized curve in N scale. You can go down to 20" and still run things like 89' auto racks with no problem. As soon as you go below 20", you'll have to start making compromises so I'd stay with 20" as the minimum for main line curves. I have 24" radius curves in HO and a 20" radius curve in N is about 39" in HO. I'd kill for that kind of radius. :) Unfortunately, I'd also have to extend the basement wall out another 42 inches and that's not very likely.
 
UP2CSX,

I am the one who posted the original message, my dimensions are 30" deep. Chimmike is "piggybacking" the post.

I remember reading some where that 18" radius in N scale is broad in terms of the curves, so that allows me about 8"-10" between the edge of the table and mainline track. Sounds like I can do a dual mainline. I would fold it on itself though, so it would have to make two complete runs around the layout so it can end up at the starting point. :eek:

That is crazy! I like it! Now I remember why I picked N scale years ago.
 
Phew, I thought I was the one going nuts there for a minute. :) Strasburg, unless I''m going nuts again, you can't get more than a 15" radius in a 30 " space. Giving some wiggle room for clearance and scenery, that gives you about a 13.5" inch radius to work with. Again, converting back to HO, since I'm not an N gauger, that would be a little over a 24" radius. That will easily run 80 foot passenger cars and 89 foot autoracks if the tracks are perfect and you take it slow. A Big Boy or Cab Forward may be stretching things a little too much though. I run 80' passenger cars on my 24" radius HO curves and, except for the unprototypical overhang, I can run a train for hours. Most six wheel engines also run fine although I have one SD-9 that doesn't like it. OTOH, my SD-40, SDP-35, and E-7 have no problems. I don't have any freight cars over 60' but I'd be a little nervous trying an autorack around that curve. It would probably make it but a trainload of them would probably lose one somewhere in the curve.
 
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I realized the basics of the whole radius this evening. Even though I know my basic geometry, I must have had a serious brain fart there. :eek: Thanks for everyone's help on this topic.


Right now, I am looking at the bare minimum of 30" deep for each side of my layout as I will have a main section that is 13 feet long. At each end of that section, I will have another six feet left and six feet right. This two "L" shaped layouts where the to of the L's meet each other. I read that 13" radius is considered conventional in N scale. With that guideline, and me wanting a double main track and some distance between the edge of the layout, I may be stretching my depth from 30" to 33" or 34".

The wheels keep on turning, and that is where I get into trouble. :rolleyes:
 
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