Mr Bach-man steam for 18in radius

[bobwrgt]

Recently noticed that on the Hornby web site they list radius and length of each model.

[uncbob]

While you are at it, you might as well include turnouts as well... a lot of people don't think about them as being a source of problems radius-wise, but they can be...

dlm

The radius that Dan is referencing is called the "Radius of the Closure Rail" or "RCR". 

John Armstrong's book "Track Planning for Realistic Operation, 3rd Edition" has a chart with various numbered turnouts in various scales and their critical dimensions.

The RCR is the tightest radius turn that a loco or other rolling stock will see on the divergent route. 

From Figure 6-4, pg. 78, Armstrong:

Note: Atlas #4 is actually a #4-1/2

HO scale

Turnout number, RCR(inches)

4,          15"
4-1/2,    22"
5,          26"
6,          43"
8,          67"

It is a good idea to match the RCR with your layout's minimum radius. 

If RCR smaller than minimum radius curve, layout's minimum radius is lowered.

If RCR larger than minimum radius, too much real estate (length) is taken up by the turnout.

If I were to err, it would be to the next (higher) turnout number...

Hope this helps,

Sincerely,

Joe Satnik       

The NMRA site says to consider a #4 as an 18"and a #6 as a 22"

[train with no shame]

i have a 4-8-4 santa fe .gotta keep it on the 22" rad .doesn't like the 18"rad . like it said above well laid 22"or better .my track isn't anchored yet .and my want became over my needs .but i like the engine . when i can expand .i will run it more . have fun keep the hobby alive !!!!!!!!!!!

[danmerkel]

While you are at it, you might as well include turnouts as well... a lot of people don't think about them as being a source of problems radius-wise, but they can be...

dlm

The radius that Dan is referencing is called the "Radius of the Closure Rail" or "RCR". 
<<< snip >>>
Sincerely,

Joe Satnik       

Joe,

Thanks for posting that.  I've never heard it and have read John's book.  I'm wondering if it was in a later version.  Mine was a pretty early one.

dlm

[Joe Satnik]

Dear uncbob,

RCR = Dimension #11

http://www.nmra.org/standards/sandrp/rp12_3.html

Hope this helps.

Sincerely,

Joe Satnik

[uncbob]

Dear uncbob,

RCR = Dimension #11

http://www.nmra.org/standards/sandrp/rp12_3.html

Hope this helps.

Sincerely,

Joe Satnik

This is from their beginners page under track

"It does take up more space, though, since it is longer. In sectional track. you could consider the No. 4 to be like an 18" radius curve and the No. 6 a 22". "

http://www.nmra.org/beginner/track.html

?

[rustyrails]

Some variation of this topic pops up regularly, and I have to say that Steam Gene is right...big locos don't belong on little layouts.  Just because an engine WILL go around a small radius curve doesn't mean that we SHOULD run it on those curves.  Personally, I love E-units and 85 ft. passenger cars, but in order to look good. they need 36 inch radius curves and I just don't have the room.  Consequently, passenger service on my railroad is provided by a "shorty" combine tacked on the end of the daily local freight.  

18 in radius sectional track exists only becuase 4X8 sheets of plywood exist.  18 inches is not some devinely inspired standard.  If you are limited to a 4X8, build a switching oval.  Use flex track and numbered switches to get really smooth track.   Buy one REALLY good locomotive (a 4 axle diesel or a 0-6-0/2-6-0) and learn how to tune it so it runs even better.  Spend some time fixing up your 40-50 ft. rolling stock to eliminate (yes, eliminate) derailments.  Build structures and make scenery.  By the time you have space for something bigger, you'll have learned the skills you need to build something bigger....and you'll understand why not to run a 2-10-4 on 22 in radius track even  if it'll go.  Just my 2 cents worth.
Rusty

[Joe Satnik]

Dear uncbob,

It's a beginners page with general statements explaining that a higher number turnout "takes up more space", or "is longer" than a lower number turnout.

I'll bet that you could get the author to change it. 

I would edit it to something like "Just as 22" radius curves take up more space than 18" radius curves, #6 turnouts take up more space than #4 turnouts."

When you want to get down to specifics, go with RP-12 and Armstrong.


Dear rustyrails,

I've said many times over that if there is room, start with a 5' width, (=30" arm reach) which allows up to 28" radius curves.  If short on room, put it up against a wall and use casters to roll it out and access the other side. 

Hope this helps.

Sincerely,

Joe Satnik   

[uncbob]

Dear uncbob,

It's a beginners page with general statements explaining that a higher number turnout "takes up more space", or "is longer" than a lower number turnout.

I'll bet that you could get the author to change it. 

I would edit it to something like "Just as 22" radius curves take up more space than 18" radius curves, #6 turnouts take up more space than #4 turnouts."

When you want to get down to specifics, go with RP-12 and Armstrong.


Dear rustyrails,

I've said many times over that if there is room, start with a 5' width, (=30" arm reach) which allows up to 28" radius curves.  If short on room, put it up against a wall and use casters to roll it out and access the other side. 

Hope this helps.

Sincerely,

Joe Satnik   

Agree on the 5'width wish I could find an extra ft but my aisle is 30"now --I may add 4 inches to my 48 so I can use a 24"radius

And as far as the 4X8 --I have a 4 by 10 and I run  a 22"radius no problem so guys with 4X8 sheets of plywood don't have to use 18"--you can go 22"--you just will not have staging on the outside