Well, i’ve decided to build myself the layout i’ve dreamt of for the past few years!!! but, its only in a 10’ x 10’ shed,(climate controlled) did i mention its in HO scale!!! yes for me its my dream layout! i’ve already designed it and have had some private critics take a look and it looks like a winner for me. (i dont have a scanner or i would share!!) it’s going to be a 4 level shelf layout, point-to-point pure operations being no more than 12" in width. its a small abandoned branch of the providence & worcester railroad called the southbridge running tracks. there will be small 6-8 car train lengths, great for me and my son to have some good operating sessions. so of course i need a HELIX… im just curious if someone can direct me to a website, or link to the calculations and formula’s i must use. i’m preferring to keep the radius around 18"-20" (room is somewhat of an issue here…) seeing as the train lengths will be small in size, i’m thinking it wont be a problem, the distance between levels from surface to surface is desired to be at 12". the first level will be at 29", the second at 41", the third at 53" and the top level (which i will need a stool for) is at 65’. i know the small radius isnt the greatest, but again im running small trains, engines being GP 38’s, train cars themselves will not be long, and the “train” will consist of 6-8 cars. if someone can direct me or offer some advice on the helix, it would be greatly apreciated.
in case i confused anyone, or if i didnt explan myself good enough,
there will be 3 helix’s one over the other, equaling one “long” run from level one to level 4.
12" seperation between levels, prefferd radius to be 18"-20"
DK, sorry! i am looking for information on how to build a helix…how to figure out calculations, like how many levels it would need to be…basically everything on helix construction!
The Atlas RTS 7.0 program (free download) will do all of those calculations for you quick and easy. You tell it the curve radius you want, how much total height you want, and how much room you want between levels, and it does the rest. As to the construction, there’s a bunch of different ways to do it. Usually you cut out semi circles of wood and overlap them, laminating them together to form your basis. Then you drill them and add threaded rods around the inside and outside edges so that you can adjust the heights infinately.
The problem you will run into is that the tighter you make your helix, the steeper the grade. If you go with a 18" radius and make a rise of 4" you will have a clearnace of about 3 1/4 inch between the plywood and the track.
Circumference=2(pi)r =2(3.14)18" =113"
4" rise in 113 inches = 3.54% grade
3.54% is very steep, but it is compounded by the fact that it is on a steep curve.
With an 18-20" Radius helix I would reconsider for a few reasons…
The radius is VERY tight and will limit what you can run.
Because of the tight radius and the fact that you are climbing at about 4%, derailments are possible and uncouplings are certain and scary (think rollercoaster).
I would reconsider your layout and go for something a bit more conservative.
hmmmmmmm…[:I] ya, now tha i look at those formulas…18" is way to small, and would make it way to steep. thank you for the advice/input, it is greatly appreciated… aftr doing some thinking… im wonderin if a 22" radius, with a 4" space between…giving me a grade 2.89 percent. I am not to familiar with running trains on grades, now im sounding like a newbie, but would that work? (running 6-8 car length trains) again thank you very much for your input guys!
IT will depend a lot on your engines. A 1800’s steamer or S-type switcher will have a problem with that grade and 8 cars. A GP-38 should have no problem, but will it clear 3.25"?
If you can find the helix photos posted by Brunton you will get some idea of what a maxi-helix looks like. (4 tracks wide in places.)
There is no Law of Model Railroading that a helix has to be perfectly circular. Adding some length (along the wall, where it won’t stick into the aisleway) will do a lot toward reducing the grade. With your specification of short trains and small locomotives, 18" radius should be satisfactory (except for the grade.) Adding 12 inches to the helix length will reduce your grade from 3.6% to just under 3%, assuming 4 inches railhead to railhead (to allow for the thickness of the track supports and allow clearance for all but the tallest rolling stock.)
Space mouse, I just measured my engine (GP 38) from wheel to top and it does clear. it does not provide me with to much vertical space for fingers should it go on the ground though (derail) hmm…maybe it will work… Thank you again for your advice/help/input, it is greatly appreciated.
I’m sorry to be the bearer of bad tidings, but that probably will not work well unless you do excellent engineering and construction and are very, very lucky. It sounds as if you don’t have a lot of experience with layout design and construction – that’s not a crime, we all start somewhere. But this layout concept and the helix to tie it together might be a bit too ambitious if you’ve never built and operated a layout with grades before.
Joe Fugate, a very experienced modeler who often posts on this forum, built a 24" radius helix for his HO layout. While nominally only a 2.65% grade, the friction of the curving track in the helix made the resulting effective grade well over 4%. Tightly curving grades create problems of stringlining (the tendency for trains to pull cars off the tracks to the inside of the curve). Also, when the steepest grade is in the hidden helix, it creates other problems for the operators.
Joe replaced the 24" radius helix with a 40" radius helix with much better results. He describes all this in the Layout Design Journal #14, Spring 1996, published by the Layout Design Special Interest Group.
It’s worth noting that fine layouts have been built in smaller spaces with multiple unconnected decks linked by operations concepts and staging. I wrote about that idea and added some more references in this thread: http://www.trains.com/TRC/CS/forums/1285535/ShowPost.aspx
I built the layout you want in a different manner and it fit in an area 5’ x 14’ so it is doable using 30" radius curves. Instead of a helix have each “module” be 30" deep and run the 10’ length. At each end you will have a 180 degree turn that will take the track to the back wall and run uphill to the next section. Now the one thing you will have to do is have the track enter your next section while on the turn. You can bring it through a cut or buildings or whatever you can think of. So if you start your rise at the start of the curve and go across the back and finish where the curve ends on the next level you should have a little over 15’ of circle and five feet of straight for 20’ for you track to rise. If it rises one foot that will be a five per cent grade BUT you said short trains so it may be livable. You will also have a five foot aisle (ballpark) from which to operate your trains in a 10’ x 10’ room. You will also have a small aisle behind the module for getting at problems on the rising section. I added a reverse loop at the top and bottom to turn trains and then backed them into storage tracks for staging. I made the middle level a division point and planned catenary on half to switch from diesel and steam to GG1s primarily. Alas a plugged sewer forced me to dismantle it as functioning sewers took precedence over trains at the time.
The rise has to be figured from railhead to railhead, NOT to the top of the car. You have to allow space for the roadbed material.
You also have to look at what your tallest car is. Just because it will clear a GP38 that doesn’t mean it will clear a boxcar or a auto rack or doublestack or a dome passenger car.
Figure 3.5 in for the cars, .25 in for the roadbed minimum plus .25 for the track (will be less in most cases) that gives you a total rise of 4 in.
If you go down to a 2% grade, that means you have to 4" up in 200 " of run you get a 32" radius. That means your helix has a 5 foot diameter. 1/4 of your 10x10 space is taken up by the helix. Your trains will be visible for 30 ft then go into a 50 ft run (12" spacing = 3 turns of 4" each turn x 200" of run per turn) in a helix.
hmm… Byron, i do have experience in designing/construction of several layouts…just not with grades, maybe im just bein too sensitive and taking your post the wrong way… i do appreciate the feedback though!
to Dave H.
i plan on running small cars, no double stacks, no passenger service, no long cars. and ok everyone cover your eyes…i see no reason to use roadbed in my helix, i have been to and operated a few other peoples layouts with helix’s that dont have roadbed and i really didnt see or hear a problem…i DID forget to figure in the height of the rail though,thank you.
to sum up everyones advice so far, i guess the 22" radius at a 2.89 percent grade will be too steep… Back to the drawing board! Thank you all for your help and advice.
Here’s how to calculate what is called the “compensated grade,” which is the effect of the actual grade with the curve-induced drag added to it:
CG = G + 28 / Radius (that’s compensated grade equals grade plus 28 divided by curve radius)
In your case, that’s CG = 3.54 + 28 / 18. CG = 5.10 per cent(!)
If you can go to 22" radius, you’re looking at CG = 2.89 + 28 / 22. CG = 4.16%
Finally, if you can add 18" straight sections between semi-circles on a 24" radius, you wind up with
G = 4/(2pir +182)100. G = 4/(23.1424+18*2)*100. G = 2.14%
CG = 2.46 + 28/24. CG = 2.14 + 1.17. CG = 3.31%
The compensated grade formula is empirically-derived (that is, derived by obsercation of effects of curves on grades. It’s the formula used by the LDSIG - the Layout Design Special Interest Group of the NMRA.
Given your small-to-medium size layout space, and the idea of a two-deck layout with a helix, have you thought of doing it as an N-scale layout?? 18"-20" radius curves are broad in N, and you could build a helix of 18" radius curves that should work quite well.
I have thought of N-scale,…i think about it all the time actually!! I’m currently modeling the same line and era in n scale, my wife has graciously let me lease a right-of-way and have a shelf layout around our BEDROOM walls (she is the best!) but my hands are so shakey (im 31…it was a injury suffered in iraq) that i can barely re-rail the cars, and trying to get the level of detail i want in N-scale is very difficult for me, so i’ve decided to go to HO Scale, and move out to the shed, its never a pleasant sight when i spill ground goop on our comforter…!!! thanks for everyones input and advice, it is greatly appreciated.
Hi. Have you considered something a wee bit different, but still will give you the elevation difference you’d like? I think an exotic helix is a lot of trackage that is hard to maintain, or access in times of trouble. How about a Vee-shaped layout along 2 walls that is almost entirely on a small grade? If the shelf-width is only 12" along the straightaways, you’d have still about 8-9’ square left for other activities; shop, seating, etc. The ends of the vee would need the requisite bulb for turning… about 54" diam, still not intruding too much.
Without doing the math, somewhat less than 32ft of straight per shelf plus twice 3’ for the middle corner trackage between levels would produce 425" of grade, and leave the bulbs level. At 2% grade, you’d have over 20" between levels. The 1 kicker is that where the rearmost track approaches the next higher level, you’d need a view-block for the last few feet to look right. Mountain tunnel or some such? Now you have 24" radius curves that will expand what you can run, and no real height restrictions on the stock, and a managable grade. You can cheat a bit and make small areas of track level for local yards/sidings, and reduce the 20" accordingly.
A small idea that may be useful. Have fun with it… George
