Helix

[ali]

hi everyone

I'm Ali and i am building a big layout for me and my son, who love trains, unfortunately i am new in this hobby and so far i just bought some Bachmann trains and buildings and some other stuff, dcc stuff , i just cannot design the layout.
I want to build a Helix first because my son love it, and as you know i don't know how to design it, if you may please help me. thanks 
the height is almost 25" and 18" radius curves

[RAM]

I do not know what you plan to run on this helix, but at 18" radius curves, I don't think you can do it.  I think you would have less then 10 feet of track per circle.  You would have about 1/2 inch rise per foot.
   

[ali]

what you suggest then? what should i do?
and how do you calculate this?

[Doneldon]

Ali-

I agree with RAM in principle but I don't calculate the needed grade as severe as he did. A 36-inch diameter circle times pi yields 113 inches per complete revolution. If you go for a four-inch rise per revolution, very close to the practical minimum, I make your grade at roughly 3.5%. This is doable but cannot be recommended. You must remember that your car (or you!) can go up quite steep hills because it has a rubber wheel turning on a paved surface. A train has a steel wheel turning on a steel railhead. That means much, much less traction. From an operational standpoint, 36 inches is a terribly tight turn for anything larger than mid-size diesels, smallish steamers, 40- to 50-foot freight cars and comparatively short passenger cars (60-foot maximum). While you may be able to commit to such limitations now, you will have a major roadblock to later expansion. Also, you will find what railroaders on the twelve-inches-to-the-foot railroaders have known for a long while: grades, and especially grades on a curve, sap a locomotive's power incredibly fast. If you have a locomotive which can haul fifteen regular freight cars on a flat, straight track, you'll find that five or six would be the max on a 3.5% grade. Throw in the sharp curve and you may be down to three or four cars. And I'm not exaggerating here; things could actually be worse. Plus, you will need to go around just over six revolutions to get a 25-inch rise which is a very long helix. And over a relatively short time, watching your trains run around in circles will get pretty dull.

You can ease the grade by going to 22-inch radius track in your helix; doing so would give you a still steep three-percent grade and allow you to move to mid-size steamers and most diesels other than the really long ones, but still limit you to the same freight and passenger limitations as before. And you would still have the penalty of what your locomotives can pull up your hill (maybe five or six freight cars at a time) and the same four plus revolutions to gain 25 inches in height. You'll also find that you now have a rather large box in your train room, one which is about four-feet square and 30 inches high.

Where this is taking me is to recommend that you pare down your plans for your first pike. One of the biggest errors new modelers make is to take on such a big project that they lose interest before they can really get trains running. This could happen in your case and it would be a shame because a model railroad is a long-term hobby that parents and children have enjoyed together for well over a hundred years. I don't know the size or characteristics of your train room, so it's hard for me to make any specific suggestions, but you might find that starting with a classic 4'x8' plywood or extruded foam train table or a narrow along the walls configuration will help you learn the skills you'll need for a larger model railroad, and get the trains running in time to reinforce your interest in the hobby. It will also be much cheaper, in terms of time and money, if your son loses interest.

Various experienced people on this board will give you some useful ideas about track planning if you tell us about your train space. You can look at many layouts on the Model Railroader web site, use Google to find track plans, pick up one or two excellent books on track planning or use one of the on-line track planning programs to see how things will go together. IMHO, you will do best if you start with us because we can help you sort out just what it is you want to do and then direct you to the planning software or other resource to bring it to life.

I hope I haven't rained on your or your son's parade with my response, but I'd rather be straight than lead you down to the garden path to disenchantment with model railroading. I've been at this for nearly  60 years and I'm still enthusiastic about the number of different aspects of the hobby and the new things to learn. Welcome to model railroading and our board. I hope this turns out to be a long and rewarding experience for you.
                                                                                       -- D

P.S. I forgot that you asked about calculating the steepness of a grade. You just divide the vertical distance of a grade by the length of the grade. That works for both straight and curved grades. For example, If you wanted to gain four inches of elevation along the 96 inches of the length of a sheet of plywood, you'd divide the four inches by the 96 inches and get .4167, or 4.17 percent. With curves, you must first calculate the track length by multiplying twice the radius (which is the diameter) by pi, roughly 3.12159. The length of an 18-inch radius curve going one full circle is 36" x pi, or 36" x 3.14159, or just over 113 inches. Divide that into the needed rise to get the percent of the grade.

[Jerrys HO]

ali

I have never wanted to attempt this feat but if you are looking for something to read about helices, here's a link for you. I read through most of it and stopped thinking of it.
There is a lot of info on each tab from start to finish.

http://modeltrains.about.com/od/layoutconstruction/tp/Building-A-Model-Railroad-Helix.htm

Jerry

[jward]

I do not know what you plan to run on this helix, but at 18" radius curves, I don't think you can do it.  I think you would have less then 10 feet of track per circle.  You would have about 1/2 inch rise per foot.
   

I think you are assuming a single turn helix. that would be way too steep, I agree.

however, in a helix you only need to gain enough height per turn to clear the level of track below. using (as I would) pine 1x4 as a subroadbed, you'd need to gain 3.75" per turn, giving you about a 6 1/2 turn helix to gain 25" in height. using 18r for the turns, doneldon's figures are accurate. btw, I used pine in this example merely as a reference point. tha actual height gain needed will depend on what the thickness of the subroadbed actually is.


to build a helix, i'd make the subroadbed extra wide, 2" wider than you would normally cut it. track ywould be centered on the subroadbed, and the next level supported on blocks of 1x4 cut to a length that allows 3" of clearance between the top of the rails and the bottom of the subroadbed of the level above. these blocks would be placed on both sides of the track, far enough from the track that your trains won't hit them, and the next turn of the helix fastened on top of them. repeat this every foot to 18" and you'll have a sturdy helix that can be extended for however many turns you need.

[Stephen D. Richards]

ali.
   Don's math is spot on and I agree with Jeff.  However, my Helix is at approx. 30 inch curves and I rise approx. 16 inches with three and a half turns.  From my experience dealing with this thing, I would suggest you stay away from 18 or even 22 inch curves.  The locos may make it a few times but even with really good track work they will derail in the helix!  Mine is just under 3% grade and I used the princple Jeff is describing.  They can be a lot of fun once they are set up correctly.  My next one will be under 2% grade.  Better to have many curves over a wider plane than short tight ones.  Hope that helps some,  Stephen

[CNE Runner]

...or you could have someone who is knowledgeable build one for you. Some time ago I saw a TV show that featured a company in the UK that specializes in helix construction. Personally, I would opt for that route (they frequently ship their products to the US). The name of the company is White Rose Modelworks. [Address = Unit 10, Bedale Station, The Bridge, Bedale, N. Yorks UK DL8 1BZ. Website = whiterosemodelworks.co.uk] You may want to search YouTube for a video of their products.

'Hope this helps,
Ray

[CNE Runner]

It's me again. I just checked the White Rose Modelworks website and they show their products (many more than I thought they made) with measurements (in metrics...there are conversion sites on the Internet if you are [sadly] unfamiliar with it) - as well as a price list (again, there are websites that will convert pounds sterling to dollars).

I also did a quick search on YouTube under "White Rose Modelworks" and there are several videos displaying their handiwork (which is probably where I heard of them in the first place).

Good luck,
Ray

[ali]

thank you all

[Terry Toenges]

Polar Express up and down the mountain
http://www.youtube.com/watch?v=Mo5VYpBE0KE

[Doneldon]

Ali-

If you are certain that you want to build a helix, and I advise against it, there are some kits which will make it easier. They are quite expensive -- I could easily see a helix the size you're talking about crowding $1000 -- but they would eliminate a great deal of meticulous cutting and fitting. Even with a kit you will need impecable construction technique and the space to fit a helix in. I wouldn't try to use a helix myself due the many possible problems, but I would go with a kit were I to change my mind in the future.

Easy Helix:
http://www.easyhelix.com/products.html

Ashlin Designs:
http://www.ashlintrains.com/servlet/StoreFront

Noch:
http://www.euromodeltrains.com/cgi-bin/search_gen.pl?company=Noch&line=HO&categoryLabel=Helix&mainGroup=helix

Lloyd's
http://www.lloydslayouts.com/index.php?p=1_6

Doneldon

[electrical whiz kid]

If you have the room-which you imply-, and the helix is going to be one of the major turn-ons" for your son, then might I suggest concentrating on the aspects of that helix that would make it safe for equipment, depandable in operation, and esthetically logical in concept.  In my opinion, the bare minimum for a helix would be 36" R., and 1/16" to 1/8" rise per foot, with special attention given to the lay of the track-no humps, bumps, sharp bends, pinches, etc, and plumb across the rails.  Also, use good quality track and wood-birch plywood is good..
Rich C.   

[Joe Satnik]

Dear Ali,

Much of this complicated planning is to allow a train to climb the helix. 

You didn't mention the age of your son.

Is he is at the age where he just wants to watch a single freight car spin down the helix with gravity?

Your only concerns then, would be vertical spacing to allow your tallest loco or car to pass, smooth track work, and

perhaps "tilting" the track inward a bit (aka "Superelevation") to help keep free rolling cars from flying off.

(Perhaps he wants to see them fly off...)

You could build a one-way "around the room" loop that ramps up on shelves along the walls, then descends on a small radius helix.

With around the room layouts, you have to be concerned about the direction that the room's entry door swings,

and a way to get to the interior of the loop (e.g. duck-unders or lift bridges).

A few options to cure an inward swinging door:

1. Pull the hinge pins and remove the door.
2. Install an outward swinging door.
3. Install an accordion sliding door.
4. Install a pocket sliding door.
5. Have the track run above the door.
6. Hang the track from the ceiling to clear the (wide) swing of the door.

Hope this helps.

Sincerely,

Joe Satnik

[electrical whiz kid]

Ali;
Listen to Joe.  He has some good points, and-again, my opinion-the helix will be a lesson in frustration unless you have some pretty good experience in either model railroading, carpentry, or both. Or have masochistic tendencies...  I promise that, for a helix you will need both.
Rich C.