re. helix from hell

Ken, I have a couple of questions.  One:  what type of steam are we talking?  Small to medium steam should be ok, while big steam like cab forwards, challengers, etc. may not.  My era isn't steam, so someone with knowledge of steam's radius requirements needs to comment.  Second:  How many revolutions are you going to make?  My helix uses 18 feet of track per revolution which sounds like about your size.  I've run trains as long as 61 cars with four SD's on the point and three SD swing helpers up all 10 revolutions of my helix, but this is really stretching the envelope!  Three SD diesels can pull 30 50' boxcars up my helix trouble free.  Incidentally, whatever issues I have tend to happen on the downgrade more than going up.  You may find some answers in this earlier thread on grades and helices:  https://forum.mrhmag.com/post/track-grade-experience-12186194 

A picture of my helix

Are you running brass or plastic steam?

I ask because the brass manufacturers make their models as close to correctly prototype as possible.  The plastic model companies will put a little "slop" in the drivers to allow them to move side to side to enhance their ability on tighter radius curves, brass models won't have this "slop."  In the case of articulated steam, the brass is even worse.  On the modular club layout, our standards require a minimum radius of 36 inches for the mainline.  Since the plastic model builders always articulate the locomotives at the center of each driver set, they work fine on our curves.  A visitor once put a brass challenger on our layout at a shopping mall show.  The "hinge" was between the rear of the front set of drivers and the front of the rear set of drivers.  As a result on our 36 inch radius curves, the smoke box swung out over the outside edge of the ballast of the outside main with the locomotive running on the inside main (two track mainline).  If you are running plastic mallets, you should have no problem as long as they will handle the 30 inch radius, but a brass model will probably require at least a 48 inch radius.

Running Plastic Steam....

The few articulated's I have are Bachmann 2-6-6-2's nd one Rivarossi 2-6-6-6.  The other loco's are either BLI Niagara's and Mikado's, MTH Mohawk's, and P2K Berkshires.  I"m very concerned about their ability to traverse the helix while pulling a standard length train. 
 

Running  16 to 20 wheel

Running  16 to 20 wheel Engines with10 axels I would expect a minimun radius of 60 inches (5 feet) is needed in order for the trains to stay on the tracks. That would take up a small room by itself 10 foot X 10 foot.

Dan

Helix Specs....

With the Upper Deck is at 66", and the staging yard for the hold the trains that begin's at the Upper Deck is at 18", and having a minimum increase per revolution of 3.5", i figure it will need 14 revolutions.  The Lower Deck Staging is at 30" with the actual lower deck located at 39".  The reason why the Upper Deck Staging is below the Lower Deck Staging is because the helix for both decks are located in the same peninsula, so one has to fit inside the other.  To prevent the occurance of one track literally crossing the other, the helix from the upper deck has to be inside the helix for the lower deck. 

I am having increasing concerns the more I think about this, not only the ability for the trains to traverse the helix.but the length of time it will take to traverse it, which is over 200' which is almost the total length of the actual mainline. I have a couple of ideas, one including using the JMRI software and block detection to bring each train up and back down to the staging deck and adding a second track to the Upper Deck Helix, which would have a 27" radius.  That would be for downgrade only, though surging then becomes an issue since the grade will probably reach 3%.  So I will have to think on this more.

Any additional thoughts and comments would be appreciated

Thanks

 

I don't see a problem with a 3% grade.

You may have some surging, but since the train is out of sight while traversing the helix, it should not be an issue.  You may need a helper to get the train up the helix, but that could be cut off and sent back down after the train arives at the upper deck, or even coupled to a train going back down.  I think I would instal an inexpensive video camera to watch the trains coming up or going down the helix to resist the temptation to excessive speed to bring them up faster.

What I would do if I redid my helix

Ken.

My helix is 10 revs, so it would be similar to yours in size.  What you may consider doing is building a temporary or test helix of only two revolutions.  You could build it to your desired specs and operate a variety of locos and train lengths, etc.  To be effective you would have to have train length tail tracks beyond the exit and entrance of the test helix.  Two revolutions at 36" radius is about 40 feet or so of run - plenty to test the performance of your locos and train while it is completely on the helix grade and curvature. 

My helix (seen in the previous post) works ok, but now that I've operated on it a while, I see several things I would do differently (assuming I would leave the rest of the layout the same and change only the helix).  First an overview of the current helix:  10revs, double track for 2 revs top and bottom, four turnouts to diverge from the helix and onto variuos decks,  6 turnouts total (four are Shinohara curved, two are Shinohara #6 straight).  Atlas Code 100 flex track soldered with expansion gaps every 9 feet. 33" radius with 5" elevation gain railhead-to-railhead.

If I rebuilt it I would do the following:  1) Increase the radius to about 36-38" to completely fill the space available (wider radius=gentler grade and less friction).  2)  lessen the grade/elevation gain to about 4" (minimum possible for clearance plus thickness of roadbed and track).  3) would use a router with a radius tool to cut precision curved roadbed (vs. bandsaw or jigsaw like I have now).  4)  I would use all curved turnouts within the helix, and I would buy a Fastracks jig and make them myself so they would be rock solid.

The current helix works, but can be finicky with long trains.  If I rebuilt it to the above specs I believe it would operate nearly flawless. 

Hope this is of a help to you.

Desperation

I don't like helixes and prefer a nolix, a long peninsula with turnback curve, etc.  I wouldn't have a helix unless it was in desperation because there was no other reasonable alternative.  I'm not a fan of elevators either.

Thanks For the Feedback so far....

Unfortunately,

- increasing the radius of the helix isn't possible, as i can not increase the width of the peninsula blob. 

- I am desperate becuase of the limited space I have, and the type and length of mainline run I need (I want even more, but that will have to wait 5 more years) so the helix is the only option. 

- For the subroadbed I was going to use either 3/8" or 1/2" Gatorfoam (need to do some testing) cut into trapazoid pieces.  There's an old IBM Basic Program from an MR article that will calculate the specs for a particualar radius to tell me what size pieces I will need to cut.  Much less waste of material than cutting curves. 

************
If I go with the helper idea, it would most certainly need to be some kind of computer-cab controlled (via JMRI Panel Pro software) to bring the trains out of staging with the helper, then cut off and return to the staging yard.  This will certainly require several block detectors at the end of the start and end of the helix.  It will will certainly need some kind of line of sight (versus a DCC Block) detector, so the front of locomotive stops at the same location every time.  A bit invovled yes, but who is going to want to deal with having to add locomotives to get in and out of staging, and then running for 200' without being able to really see (though the security camera is a very good idea! Maybe 2 to have different angles)  but it's not going through scenary which is no fun.

Thanks again! 

I still would welcome further feedback from anyone on this isssue.

Ken L.

 

Don't use roadbed in the helix.

Put the track directly on the subroadbed, and save 1/4 inch of verticle clearance.  Since the track is not in view, there is no need to have nicely detailed roadbed, ballast, etc.

To use roadbed or not....

I'm debating whether to use roadbed or not.  I agree there is no need for it for visual purposes, but for sound issues, I may still want to use it.  Having track directly on gatorfoam or plywood is very noisy, and the sound of the train traversing the helix might be a distraction.

Ken L.

Roadbed and Helpers

A helix needs to be built solid up front and stay that way. I have built a couple of helixes using 1/2" plywood connected using a biscuit joiner to avoid having splice plates, and attached the biscuits with polyurethane glue for greater strength than plain old yellow wood glue.

I'd be concerned about the long-term structural rigidity of something like Gatorfoam for this application. What happens when something is dropped on the helix during layout construction?  How does a faced foam product hold up when someone bumps the helix while rerailing cars or cleaning track?  Yeah, you can probably build with the Gatorfoam but I'm not sure I'd like to see the thing after five years. 

Plus having that helper in operation sounds to me like trouble waiting to happen, especially if it's automated.  You're talking about relativley steep grades and sharp curves for the equipment you prefer, so you're already asking for reliability problems, now layer hidden track and computer control on top of that so there's no supervision of trains running and stopping at set locations, not to mention automating the return trip for the helper back to staging.  Murphy's law should have a whole subchapter for this.

Not going to be used any longer than 5 years....

This layout is only anticipated to be used for up to 5 years, so the longevity issue is not as much of a concern, though I am awaiting response back from those who use Gatorfoam to report back to me the practical use of it for this specific application.

As for the Helper issue, the biggest issue I expect would be the point where the helpers would connect and disconnect with the trains.  Since I plan on having the helpers on the HEADEND of the trains (versus pushing) this mitigates somewhat the possibility of inviting Murphy for a visit. Where the locomtoives do connect and disconnect with the trains will be out in the open, not hidden track.  And I plan on using 4 Powered Diesel Units which should be more than sufficient to pull the trains up the helix.  There will be cameras in the helix so there is a way to see what is going on should there be a problem.  There will be Line of Sight detection units so that if a train stops, it will be detected, and an "alarm" will go off.  That's the plan thus far, and it's still developing, so we shall see.

Ken L.

I don't know about HO but N

I don't know about HO but N scale has Thin Foam roadbed i plan to use on my Helix. The rest will be cork....i thin...

I'm wondering if Dynamat would quiet things?

I'm thinking of the thin rubber sound proofing material thta hot rodders use on the interiors of their cars to quiet squeeks and rattles.  I think Dynamat is more like 1/8 inch thick rather than 1/4 inch.

Helix Roadbed

The overall dimensions of the helix don't sound like that big of an issue - 33" radius is very reasonable.  I would cut the rise from 5" to 4".  My helix has a 4" rise between levels.  I'm using 1/2" plywood with 1/2 homasote.  Both the plywood and homasote are cut to shape using a template and router.  The homasote is 1/2" narrower on each side, this allows me to place the spacer riser on the plywood, which is more stable, instead of the homasote.  The plywood joints are down with biscuit joinery so there is no splice plate underneath the joint.  The plywood and homasote joints are staggered.  Narrow arcs of plywood are placed on the each side of the homasote where there is a plywood joint.  These serve as splice plates, but are on top instead of below which means that the thickness of the subroadbed/roadbed is constant.  I don't use cork on top of the homasote.  The combination of plywod and homasote glued on top creates a very strong sandwich.  The risers are 1x4 poplar cut into 2" wide blocks.  Since the actual dimension is 3-1/2" tall, add another 1/2" for the plywood and you get a 4" rise.  Another imprtant consideration that no one has mentioned is to give plenty of thought as to how you are going to run your feeder wires.

More on Gatorfoam

Yesterday I visited the layout of a friend who is modeling in 1/35 scale two-foot gauge.  The structures he is building are often huge, so he is building a lot of them on gatorfoam cores, including the 1/2" material, which I hadn't worked with before.  We discussed using the 1/2" Gatorfoam for roadbed and messed around with some large scraps to judge the strength.  The group of us present all agreed that Gatorfoam might work for roadbed, but that it lacked rigidity for such an application compared to more traditional materials like plywood.

"Temporary Track"

Ken,

I just had to respond to your comment about not anticipating using the helix for more than 5 years.

I can pretty much assure you that with as much work as you will put into it, unless it's an absolute disaster to run you will do everything in your power to keep it as part of your layout.

To loosely paraphrase scripture - "Where your brain strained, sweat stained effort is, there your heart will be also."

IOW, I would plan for the long haul instead of planning for obsolescence.

Some parts will literally go the way of the chainsaw...

Sorry Jeff, I have to disagree with you on that point.  The Ultimate P&A will NOT have a helix of this tight of a radius.  There might be a helix to access auxillary staging (i.e. storage) tracks so I don't have to add or remove cars in between sessions, but that will have a much broader radius.  Other areas that will be literally ripped out will be those modules that will not meet the Ultimate P&A standards (Givens) such as those modules that have a 36" Radius for the Interim Plan will not pass the 48" minimum radius for the Ultimate Plan.  Because I am using insulation foam as the subroadbed, I will be able to "recycle" many parts, inlcuding the poly-fiber trees, and even super trees and indiviual conifers. 

Ken L.