ahh the helix......questions of course!!!

[mammay76]

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" 

thanks in advance for reading and your input. 

 

Joe

[dknelson]

I am not sure I entirely grasp your question.  I will point out that there is a commerical helix kit available.

Website is

 http://www.easyhelix.com/

Photo from website

Dave Nelson

[mammay76]

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!

Thanks for the link, i'll check it out!

[pcarrell]

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.

[SpaceMouse]

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. 

A 26" radius will get you a 2% grade.   

 

[mammay76]

hmmmmmmm..... 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!

[SpaceMouse]

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"?

[tomikawaTT]

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.)

Chuck (modeling Central Japan in September, 1964)

[mammay76]

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.

 

Joe

[cuyama]

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!

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/trccs/forums/1285535/ShowPost.aspx

Byron
Model RR Blog

[ndbprr]

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.

[dehusman]

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.

Dave H.

 

 

[mammay76]

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.

[SpaceMouse]

Don't forget the previous idea of an oval helix.

[exPalaceDog]

Here are some old spead sheets I did a year or two ago on this topic

 

Car length calculation

 

A)                    B)

40                   6

50                   8

60                   9

70                   10

80                   12

 

• A) Length of car/loco in HO feet
• B) Length of car in actual inches with allowance for coupler

 

Train length calculation

 

                        A)                    B)                    C)                    D)                    E)

psgr                10                   120                 3                      24                   144

frt                   30                   186                 4                      32                   218

psgr                8                      96                   2                      16                   112

frt                   24                   150                 3                      24                   174

psgr                6                      72                   2                      16                   88

frt                   18                   114                 3                      24                   138

psgr                4                      48                   1                      8                      56

frt                   12                   78                   2                      16                   94

psgr                2                      24                   0                      0                      24

frt                   6                      42                   1                      6                      48

 

• A) Number of cars - 40ft for frt, 80 ft for psgr
• B) Length of cars in actual inches - counting caboose as on car
• C) Number of locos - assume EMD E or F units at 50ft per unit except for last row which assumes 40ft SW 1500. Next to last row assumes self propelled RDC or gas electric cars
• D) Length of loco's in actual inches
• E) Total length of train in actual inches

 

Note 01) The first four rows represent trains on primary mainline

Note 02) The next two rows would represent trains on secondary mainlines

Note 03) The last four rows would represent branch or short line trains

 

Opinion 01) The value of ten cars used for primary mainline passenger trains assumes the following consist - RPO, Baggage, three Pullmans, Dinner, three more Pullmans, and an Observation car.  The Pullman cars would probably be Parlor cars on short haul day light trains and Sleepers on long haul and/or night time trains.

Opinion 02) It is assuming that six revenue passenger cars would be required to provide adequate patronage to justify a Dinner and Observation car.

 

Comment 01) Moving back in time would reduce the train lengths. For example eight fifty foot passenger cars would only require 64 inches. Open platform cars would eliminate any need for a Dinner or Observation car.

Comment 02) Use of steam engines would require less length then diesel units in many cases.

 

Available track length calculation/s

 

A)                    B)                    C)                    D)                    E)                    F)

G)                    H)                    I)                     J)                    K)                    L)

XX                  XX                  XX                  XX                  XX                  XX

 

 

• A) Radius
• B) Circumference
• C) Amount of straight track added within circle
• D) Not Used
• E) Length of track leading to and from helix
• F) Not Used
• G) Amount of circle used (.25 = 90 degrees)
• H) Desired raise, NMRA minimum standard is four inches
• I) Length of track including any added straight track
• J) Resulting grade to archive specified raise
• K) Length of track when leads in and out are included
• L) Resulting grade to archive specified raise

 

Note 01) The grade for a full circle and 4 inch rise in the minimum grade for this radius that will allow adequate clearance

Note 02) The maximum grade used should probably be limited to 4 or five percent

 

 

A)                    B)                    C)                    D)                    E)                    F)

19                   119                 0                                              38                  

G)                    H)                    I)                     J)                    K)                    L)

0.25                4                      29                   .138                67                   .060

0.50                4                      59                   .068                97                   .041

0.75                4                      89                   .045                127                 .031

1.00                4                      119                 .034                157                 .025

1.25                8                      148                 .054                186                 .043

1.50                8                      178                 .045                216                 .037

1.75                8                      208                 .038                246                 .033

2.00                8                      238                 .034                276                 .029

 

22                   138                 0                                              44                  

0.25                4                      34                   .118                78                   .051

0.50                4                      69                   .058                113                 .035

0.75                4                      103                 .039                147                 .027

1.00                4                      138                 .029                182                 .022

1.25                8                      172                 .047                216                 .037

1.50                8                      207                 .039                251                 .032

1.75                8                      241                 .033                285                 .028

2.00                8                      276                 .029                320                 .025

 

25                   157                 0                                              50                  

0.25                4                      39                   .103                89                   .045

0.50                4                      78                   .051                128                 .031

0.75                4                      117                 .034                167                 .024

1.00                4                      157                 .025                207                 .019

1.25                8                      196                 .041                246                 .033

1.50                8                      235                 .034                285                 .028

1.75                8                      274                 .029                324                 .025

2.00                8                      314                 .025                364                 .022

 

28                   175                 0                                              56                  

0.25                4                      43                   .093                99                   .040

0.50                4                      87                   .046                143                 .028

0.75                4                      131                 .031                187                 .021

1.00                4                      175                 .023                231                 .017

1.25                8                      218                 .037                274                 .029

1.50                8                      262                 .031                318                 .025

1.75                8                      306                 .026                362                 .022

2.00                8                      350                 .023                406                 .020

 

22                   138                 48                                           44                  

0.25                4                      82                   .049                126                 .032

0.50                4                      117                 .034                161                 .025

0.75                4                      151                 .026                195                 .021

1.00                4                      186                 .022                230                 .017

1.25                8                      220                 .036                264                 .030

1.50                8                      255                 .031                299                 .027

1.75                8                      289                 .028                333                 .024

2.00                8                      324                 .025                368                 .022

 

Have fun

[Pruitt]

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/(2*pi*r +18*2)*100.   G = 4/(2*3.14*24+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.

[wjstix]

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.

[mammay76]

explacedog.....WOW!!!  very nice thank you. 

Brunton: Thank you very much for that formula!

 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.

 

Joe 

[BigG]

  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

 

[last mountain & eastern hogger]

Hi Joe,

There is nothing to be scared about building a helix.  It seems a little daunting to start but once you get rolling it is very repetative and goes well.

One thing that I found and it is in an older issue of "Model Railroad Craftsman" is that when building roadbed either curves or helixes if you cut your pieces straight with I believe it is 22.5 degree angle on the ends, you will use far less material. Now when putting it all together and making the ends meet securily, with the material that you use to fasten them togther, that must be taken into account for your vertical clearance as well.

Good luck and go for it.

Mine is in "HO" and I have 27" radius (radii) , 4" vertical clearance and 16" to the lower level.

I pull 10-14 car trains with two units of power. I am manly diesel and this gives a good reason to double-head.

All for now.

Johnboy out..........

James:1 Verse:5

The "Wobbly will wobble this afternoon. 

I am at work right now and don't have the information available or I would give you the issue of that mag.

[exPalaceDog]

This is another option for changing levels

http://www.ro-ro.net/

 

Have fun

[mammay76]

last mountain & eastern hogger: thanks for the advice/encouragement!  i was actually thinking of following P & W prototypical standards of running a engine on the front and back...might look a bit silly with only 6-8 cars though..but they i have seen the real P & W with only 8-10 cars engine on the front, and one on the back. which i guess....now the light bulb is going off in my head!!!  it would cancel the "stringing" effect in the helix, and i think would work........Thank you!! 

[last mountain & eastern hogger]

Joe,   In reply to the tail pusher scereno,  it is really difficult to get two locos ,no matter if they are the same brand, to operate exactly the same. Therefore you have much better luck in having them together in the lead and just "fighting each other" rather than this fight going on with a number of cars in between. You will have definate problems in doing that.  Don't bother to ask me how I know that.  My thoughts were that if I ran one at the end coming up then I would not have a problem if a coupler failed. There would be no runaway. But since I changed to running both power units on the lead I have not had any problems.

Do your very best track laying on the helix.  If you haven't laid track before then start on your yards or a branchline and get your skills down PAT before you start on the helix. You do want it to be as good as you can get it. This will solve most of the problems.

That magazine article that I mentioned earlier is in the December 2004 edition of  "RAILROAD MODEL CRAFTSMAN". Pages 88-89-90. Titled "OCTAGONAL HELIXES"  There is a write up as well as all the diagrams and also the cutting diagram for the sheet of plywood.

Hope this helps you out. and good luck.

Johnboy out............

James:1 Verse:5

The "Wobbly" wobbles on in the Great White North.

[mammay76]

i do have quite a bit of experience laying track, so it shouldnt be a problem...as long as i take my time. i plan on leaving my current layout up and running while im building the new one, so i dont get those "i want to run trains now thoughts"  which would lead to rushing to complete the trackwork, which we all know what the result would be....

   the head-end scenerio might give me a problem just like you metioned...

 thank you for the research into the reference you gave me!  i'll definately check it out!

 thanks  again,

Joe

[tgindy]

Here are some really good helix links.

6-page => "A primer on helix design" by Doug Gurin:

"1997 Model Railroad Planning"...

http://index.mrmag.com/tm.exe?opt=I&MAG=MRP&MO=1&YR=97  

PDF Station Download => "A Guide to helix and staging design"...

http://kalmbachcatalog.stores.yahoo.net/mrpdf032.html 

Three useful "Helix & Grade" forum threads:

http://www.trains.com/trccs/forums/958698/ShowPost.aspx

http://www.trains.com/trccs/forums/1192534/ShowPost.aspx 

http://www.trains.com/trccs/forums/1014613/ShowPost.aspx 

And => Here is Brunton's "The Behemoth Helix" webpage: 

http://www.thecbandqinwyoming.com/CM%20-%20Behemoth%20Helix.htm 

[mammay76]

Tgindy, thanks for the links!   wow, i'm very impressed by the layouts some of you guys are working on!! I'm glad i finally started reading/posting on the forums, you guys have been a great help so far, and i really enjoy checking posts to see peoples work, and the advice you guys have offered.   Since posting, i have now gone back to the drawing board, trying to gain a larger radius, while still reaching my objective. I'm hoping...keeping my fingers crossed!!  thanks again.

EDIT: i exploring/ looking into an elevator, trying to re-arrange/mirroring the layout levels to make sure the train is travelling the right direction. there are some good benefits to the elevator

the good:

I gain alot more space

I can actually get an extra few feet of model space on each level

the bad:

it would eliminate the length of my mainline run, which is somthing good the helix would do for me, make the run from level 1 to level 4 seem longer.

the good do out weigh the bad, but still, im not to sure if this is what i want!!

so, its somthing i am thinking about,, i'm in no rush to jump into this, i want it to be done right,and operate right, and i want to be happy with it.

Joe

[MisterBeasley]

I would assume that your 10x10 space would be used for an around-the-walls layout.  If that's so, then you can build a ramp along the back walls, hidden by scenery if desired, that will give you a nice long run with only a couple of curves, and you can maintain a gentle grade all the way up.  Unlike a helix, though, you can't just stack on another layer to go higher.  With long ramps you're limited by the length of the run.  On the other hand, you can use the climbing track for interesting scenic elements like bridges and trestles at the back of the layout.