help designing a helix

[nik_n_dad]

hello.

We are kicking around what our next layout will be (and thanks for the pointers so far). We are headed towards putting a helix from the main level to a level under the layout where we'll do staging.

we're in n-scale, and the helix will probably end up being roughly 30-36" to provide adequate access between the levels. We run a broad mix of things, from short cars and trains with 3-4 cars to very long frieght trains, bullet trains and passenger trains like the super chief or morning daylight.

So here's the questions...

1) what's the minimum and ideal radius for the helix?

2) flex or sectional track?

3) if flex, do you still follow the rules of which rail is in the inside or the outside?

4) recommended grade?


thanks again for the help

[jrbernier]

 Here is what I would suggest:

• You want as generous a radius as possible.  For N, 16" to 22" would be my minimum.  There is a lot of 'drag' in those curves. 
• Use flex track - less joints, & swap every other sections loose rail 'outside, then inside'.  And solder feeders to every section of track.  You want this to be 'bullet proof'.
• For grades, you need to be able to get your hand in between the levels to rerail a car(yes it will happen).  To get a 4" seperation, you will have a 2.9% grade.  A 3" seperation will give you a 2.1% grade.

  Be prepared to assign extra engines to get trains up that helix!

Jim

[mammay76]

i am in the process of completing a n scale helix for a double deck layout. (one more level to go!!)It has a 16" radius and 3" seperation between levels.so far so good, i have run these train lengths up and down quite a few times and havefound that i need 2 engines to take the trainup the grade smoothly. i would definately suggest using flex track and absolutely soldering the rails. to make my life easier i would solder 4-5 sectios of flex track together...then wrap it around the helix using a hot glue gun to keep it in place,,,making the process alot easier. (i also suggest gluing in 6" sections....lay the glue down, THEN place the track on it!! i alos added feeder wires to each level of elevation on the helix. i found that with a 16" radius it uses about 4 pieces of flex track per reveloution. hope this helps some! good luck!!

[murrietajazz1]

I just finished all my benchwork and have a 13'6" wall turning into a 21' wall and then a 9' wall so on the big end I built a 66" bench so I could build a 30" and a 28" radius separated by 2" center to center track on a 6" wide 1/2" plywood so I would have the room on each side of the inside and outside track for my supports for the next level of helix, which I made 2" of clearance rail top to underside of the plywood.  This gives me a grade of about 1 and 1/4% with super huge curves.  I built the bottom section of 1/2" plywood supported by vertical 3/4" risers with cleats on top so when the helix was finished I could easily unscrew the verticals from the bench frame work to adjust the grades until they were perfectly even.  I have laid 172 feet of double mainline track (N scale) and have a Union Pacific passenger unit of ABBA and 13 cars and am currently running another 25 car freight pulled by a Dash 8 and an F3.  What a great sight watching these run all over the layout!  I would recommend the biggest radius you can get which will also give you the smallest grade to the next level.  My maximum grade is 1 and 1/4% so I should have no problem with the longest of freights. The 2" clearance on the helix is plenty for the tallest loads. All the bench work is of 3/4" plywood ripped to 3 1/2" widths and is very strong, even with 24" spacing so i can easily get under the two large mountains in case I get a derailment.  I soldered all the flextrack and put in plenty of leads off the main busses.  All the joints are tight and even and I have yet to have a derailment.  I used all Peco large radius turnouts and they are a dream to work with. I put the moveable rail to the inside of all curves and that seemed to work out just fine.  I soldered all the rail around the helix together and held the rail in place with stickpins and then went back and moved the rails aside and then used adhesive caulk bead down the middle of the cork roadbed and then used a putty knife to smooth the caulk off.  I put the rails down the middle of the cork and they stuck in place almost immediately. I highly recommend this technique. Good luck.

[tgindy]

36" x 36" are the current N Scale helix plans for the CR&T.

Here's a Forum Helix Jem, "aah the helix," that will answer many questions to come...

http://cs.trains.com/forums/2/1288809/ShowPost.aspx#1288809

[tgindy]

I bet the thread you highlighted is a real Gem!

Gem is Jem's fraternal twin. 

[mammay76]

heh.....yup that was my post!!! it definately helped me out alot, made the chnges i needed to make and as i posted earlier....everything is going just fine...except the allowance the wife gives me!!!!  good luck!

[HarryHotspur]

Dad -

This is just for what it's worth, but I have built one helix and it will be my last. It was difficult for me to build (I'm not very experienced) and very cumbersome. It worked fine, but was impossible to scenic. I tore it out after a few days.

I'm not in the habit of discouraging anyone who wants to try something challenging, but it looks to me like you have plenty of room for a really nice N scale layout on one level. If I were you, I would seriously consider starting with a less challenging one level layout (which is not to say all the tracks have to be flat) with a provision to add a helix and second level later on if you want to.

On the other hand, if you really like the idea of a helix, go for it! Plenty of people less talented than you have built them quite successfully. 

[cregil]

...It has a 16" radius and 3" seperation between levels.so far so good, i have run these train lengths up and down quite a few times and havefound that i need 2 engines to take the trainup the grade smoothly. ...

If that 3" is between the ceiling and the floor inside the helix, and you are using 1/2" ply, that is a about a 3 1/2% grade.  

If the 3" is between floors inside the helix and using 1/2" ply, then it is about a 3% grade.

A 16" radius is almost exactly 100" of track per revolution.

My idea is to use a minimum clearance (N-scale) of 1.75", 1/4" ply, and at a 16" radius = a grade less than 2% and a 2" change in height for each turn.  More turns, more track, more need for "bullet-proof".  It is to be built in a cabinet, accessible from at least three sides with hinged cabinet doors.  In the center of the hollow, a thick foam pad.  No hands need get in, just a stick to nudge derailed equipment over the edge into the foam.

I have a sentimental childhood track plan to rebuild intended as a un-prototypical peninsula that is 36" wide.  The helix cabinet forms its base, and (as all childhood layouts should have tunnels) this layout happens to have a tunnel track at edge, that can be directed to a downward helix in the dead center of the layout.

By the way, realize that if your layout can have a dedicated downhill track, you can put that inside the radius of the climbing track-- as long as the inside radius can operate your equipment. 

I offer for consideration, and I'm open to critique. 

Crews 

[last mountain & eastern hogger]

 Hi Nik n Dad,

 A Helix  can be a lot of fun or a real pain in the backside.

There has been lots written about them, myself included.

Go to the search key at the bottom and type in Helix, there is more information there than you could need in three lifetimes.

My helix is a smaller one at 27" radius, 4.5 loops and quite steep at 4.25' per loop. It is my way up and down to Staging and engine facilities and some industries.  It works fine with 12-14 cars but the trains have to be double headed.  One loco just can't handle it. But gives a great reason for a helper station.  My article in there tells about a RMC article about using all straight material and cutting 22.5% on the ends to form your curvature.  Much less waste of material that way.

The Grand Daddy of them all is the one that Mark Brunton built.  I think he was trying to get to the pearly gates by train..

Put your best trackwork here,  practise in your yards first. You can't believe how fast a car or the rest of the train goes down it into oblivion when a coupler fails or a derailment.  You end up with lots of workbench repairs to get things back up and running again (hopefully not always)

Good luck

Johnbot out..............

[Pruitt]

Here's my own helix in HO:

This link tells you how I built it: http://www.thecbandqinwyoming.com/CM%20-%20Behemoth%20Helix.htm

Most of the info is applicable regardless of scale.

Make the radius as large as you can. It will help when it comes to stringlining and making it up the grade. Remember that the drag in a curve increases the apparent grade of any rise. Your train length will suffer. A larger radius not only reduces the actual grade, but it reduces the effect of the curve drag, and makes stringlining less likely.

There are several downsides to a helix: First, in a big one (like mine), trains will stay out of sight for a long period of time; Second, they hear up a lot of real estate, especially the large radius ones; and third, they use up an amazing large amount of track!

If you'll be a the Mid-Eastern Region convention in Reston, VA in October this year, I'll be giving a clinic on helix design. Drop by - maybe I'll say something helpful!