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What is the ideal location for a helix (in this space)?

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What is the ideal location for a helix (in this space)?
Posted by TrainzLuvr on Saturday, August 05, 2017 3:36 PM

Hello all,

I wanted to start a new thread because I'd like to get more feedback on this specific question since it is not scale related, so all scale modelers please chirp in!

The following is the space I have for my layout, and I'm looking for the ideal/best location for a potential helix. This would also be the least useful location for anything else, as helicies are huge space wasters, so they need to go somewhere out of the way.

If you have other alternative suggestions not shown here, please elaborate.

The two columns at the bottom are immutable (they hold the house main floor).

The first helix option is a 5' circle:

The second helix option is a 6.5'x5' oval:

I hope these are clear enough but if not I can provide more details.

Thank you!

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Posted by selector on Saturday, August 05, 2017 4:13 PM

TrainzLuvr

... This would also be the least useful location for anything else, as helicies are huge space wasters, so they need to go somewhere out of the way...

 

You kind of contradict yourself, or conflict your purposes, all in that one sentence above. The 'best' place for a helix is where it complements your track plan and the intende purpose you have in mind for it.  Yup, it takes up a lot of space, and it makes hidden tracks...a lot of it.  It needs all that space so that you con't have stalled consists inside it somewhere trying to get around the too-tight curves and safely/reliably up the too-steep grade.

We don't know your purpose, nor your track plan as a concept, so it's really not practical for anyone to offer a suggestion as to the 'best' place for one.  We don't know how large it will be, how many complete loops.  Can you keep it small, say to 24" radius?  Or, like I did on my last layout, decide that I wanted a lot of leeway with my locomotive power and to keep the grade to 2.2% or less?  That meant about 6' in diameter, a bit under.

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Posted by RR_Mel on Saturday, August 05, 2017 5:47 PM

My HO helix has 32” radius and I believe that to be the sharpest possible radius for a grade in excess of 2% to prevent derailing with long consists.
 
My grade is 3½% for a 10” rise with roughly 33’ of track and I’ve never had a derail.  Most important is the vertical transition, my transitions are 28” in and out of the helix.  
 
 
Mel
 
Modeling the early to mid 1950s SP in HO scale since 1951
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
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Posted by gregc on Saturday, August 05, 2017 5:53 PM

considering the layout suggested in the other thread and Byron's advice in the past, why not put the helix on top of the loop on the pennisula?

however, you may want to consider the Effective slope caused by curves, http://cs.trains.com/mrr/f/11/t/221186.aspx, when considering the radius of the helix.

greg - Philadelphia & Reading / Reading

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Posted by TrainzLuvr on Saturday, August 05, 2017 6:46 PM

I suppose helix is part of the layout, yes, but from what I could see is that most people tuck theirs away in another room, an alcove, outside their building, if they can. True, some put them as part of their loopbacks or reverse loops but that's only when they are tight on space. Then again I guess I'm tight on space, too.

The helices in the above samples are single track H0, as noted 5' diameter and 6.5' x 5, which equates to a 28" radius without, and with 18" straight portion in the middle.

They produce a 2.29% and 1.89% grade on a 4" rise per turn. Calculating for the centrifugal force on a 28" radius (1.1x multiplier), the effective grade becomes 2.5% and 2.1% respectively.

The trains will not be longer than 12-15 transition era box cars, if at all, so the grades seem quite acceptable to me. Or did I get all this wrong?

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Posted by gregc on Saturday, August 05, 2017 7:11 PM

TrainzLuvr
They produce a 2.29% and 1.89% grade on a 4" rise per turn. Calculating for the centrifugal force on a 28" radius (1.1x multiplier), the effective grade becomes 2.5% and 2.1% respectively.

the effective grade adjustment is not a multiplier, it's additive.  the effective grade is 3.6% (2.5 + 1.1).

 

With a pennisula, i figure there is roughly 100' per circuit around the room.   Accounting for a limited number of flat areas for stations, I wonder if it's practical to achieve a 16" change in height with a constant grade between 1.5 and 2%.

greg - Philadelphia & Reading / Reading

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Posted by CMStPnP on Saturday, August 05, 2017 7:58 PM

I am having a layout built for me with a Helix, I think I specified the minimum radius at 30" but I would like to raise it to 36".    Also, I think my Helix is going to be framed independently from the rest of the layout and mounted on wheels.    Because it will both block a window and room closet door.    I need to get access to both when the layout is not in operation.

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Posted by TrainzLuvr on Sunday, August 06, 2017 10:45 AM

@gregc

I was going based on this: http://www.timstrainsandhobbies.com/wp-content/uploads/2011/09/HELIX.pdf?#page=20

If that is not correct then my bad.

 

@CMStPnP

If you have another area big enough to hold a 36" helix (that's 6.5'+ diameter object that's wheeled around) when not in use, why not just put it there permanently?

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Posted by gregc on Sunday, August 06, 2017 1:36 PM

TrainzLuvr
I was going based on this: http://www.timstrainsandhobbies.com/wp-content/uploads/2011/09/HELIX.pdf?#page=20 If that is not correct then my bad.

Byron described "effective grade cause by a curve"  in the thread I referred to

cuyama
The most common rule-of-thumb is that proposed by John Allen. For HO, this is expressed by the formula 32/R, "R" being the radius in inches. The result is the additional grade percentage to be added to the nominal grade. For 22" radius, the result would be 1.45%, added to your 2% nominal grade would be 3.45%.

On flat ground, a 32" curve has an effective grade of 1%.   If a train weights 100 oz, there's an extra 1 oz of friction the locomotive must pull.

greg - Philadelphia & Reading / Reading

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Posted by Choops on Monday, August 07, 2017 7:52 AM

For your space the end of the peninsula.

Steve

layout 31-1

Modeling Union Pacific between Cheyenne and Laramie in 1957 (roughly)
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Posted by TrainzLuvr on Monday, August 07, 2017 8:17 AM

Thank you for these drawings, they are very helpful.

One question, it appears that the lower level does not have a divider along the peninsula, is that correct?

My understanding is that dividers are used to obscure view of the whole layout at a first glance (at the entrance point) and also provide separation between areas - one side is far away from the other.

Would it work if there was a divider on the lower level, and how do I execute that since then one side ends up empty?

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Posted by Choops on Monday, August 07, 2017 8:31 AM

lower level of peninsula is visible from entrance side of layout (single sided peninsula.  the top level of the peninsula is visible from the back isle only.

cross section would be like this

l

l

l

---------  (upper level)

          l

          l

          l

---------  (lower level)  

Steve

Modeling Union Pacific between Cheyenne and Laramie in 1957 (roughly)
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Posted by CMStPnP on Wednesday, August 09, 2017 9:55 AM

TrainzLuvr
@CMStPnP If you have another area big enough to hold a 36" helix (that's 6.5'+ diameter object that's wheeled around) when not in use, why not just put it there permanently?

Well first, I cannot believe they have trainset builder and consulting companies now....I think that is a really great development and could have used input way back when I was a kid on my first layout.    My Father was stumped on some of the electrical issues which technology has mostly made a lot easier to resolve today.

Second, one of the reasons I am paying for a firm with experienced Model Railroaders in it is to help me out with planning for some of the new concepts since I last had a functioning HO Scale layout (1988).   I thought a lot about the HELIX size in my head while planning and built in flexibility for it with the layout.  

So to answer your question since I am building in a spare bedroom my layout will be largely U shaped with a large cutout in the middle, and I intend to slide the HELIX there.    Because it is 6.5" in diameter means nothing because it is modular and on wheels and I have a 9 foot cieling in the room we can engineer a solution to push it into that cutout and maybe elevate it above the trainboard (the base supporting the helix can easily be smaller than 6.5 in diameter to make this feasible.     During hours the train is not in operation I want access to the Window and closet      The U shaped layout leaves about 4 feet for a walkway across the top with the Window and closet together at the end of the walkway.    So I just need to possiblly shorten one of the U shaped legs 2 feet and maybe cut the radius a little to get to 5 feet approx if needed.    The Helix is only going to be used to take trains between the 2nd level and third level.    So it will extend from trainboard height to the second level.     First level or staging area will be 24-36 inch below the regular running middle level so I can reach the staging area with a ramp.    So the base of the Helix can be smaller than 6.5 feet.    We can also ramp up via embankment from the trainboard to the helix entrance and have the Helix already elevated maybe 2 to 3 inches above trainboard level a little then slide it up a little more to clear structures and scenery while it is pushed into the mid section.........Pretty confident we can get it to work.     The layout company is building a custom helix, I am not buying one pre-made......I dont think.   We'll figure it out.    I might not have the space at trainboard level but I do have it vertically.

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