S Scale Double Helix Help Needed:

Discussion in 'S Scale' started by Gettysburg, Dec 13, 2008.

  1. Gettysburg

    Gettysburg New Member

    Does anyone have any info at all on constructing an S Scale double helix? I have been smitten by the bug after seeing an O Scale double helix in operation. I am attempting to avoid long and frustrating trial and error. Any and all help/advise will be greatly appreciated.
  2. BoxcabE50

    BoxcabE50 Staff Member TrainBoard Supporter

    You might also ask in the Layout Design Forum. I know we have several folks there who have designed and built some nice HO or N helixes.

    Do you have any part of your layout built? Am wondering if there are a few photos we could view?

    Boxcab E50
  3. Gettysburg

    Gettysburg New Member

    Thanks for the direction. Still searching. I want to build a "Double Helix" for S Gauge. Most all info along with specs are smaller gauge specific. My layout is quasi up and running. Reviving an old 12'x8' layout which is involved (14 switches and "Complicated Reverse Loop". The Double Helix is to be a stand alone unit off to the side. I have no need to reach a second level (yet). The constant motion achieved by a double would be interesting to observe as a stand alone.
  4. ppuinn

    ppuinn Staff Member TrainBoard Supporter

    Welcome to Trainboard!
    "Double Helix" can be defined in 3 different ways.

    Do you mean 2 helixes side-by-side with one single track rising up one helix and passing over to the second helix (whose central axis is over a different center point) where a single track descends back down to 0 elevation, and then passes back over to repeat its rise up the first helix?
    Do you mean a genuine double helix with 2 helixes of different radii (one inside the other, sharing a common central axis) with one helix ramp spiraling clockwise upwards and the other ramp spiralling clockwise downward?
    Do you mean a double tracked single helix with two tracks running side by side up a single helix ramp...trains would rise up one track (probably the outside track due to the shallower grade), loop around a teardrop shaped loop at the top, descend back down the helix ramp on the inside track, and then loop around a second teardrop shaped loop to reverse direction and repeat the cycle by starting back up the ramp on the outside track? ?

    Since the stand alone double helix will be more for display rather than incorporation into the layout, will you be transporting it to train meets or shows (so construction should be lightweight for portability)? Or is it just for entertaining visitors to your layout (so construction can be somewhat more permanent--maybe even attached to the wall)?

    How much space would you like to devote to the Double Helix? For the Genuine Double Helix (outside track rising clockwise, inside track descending clockwise), your minimum foot print would be determined by the minimum radius of the inner track helix and the radius of the outer track helix. I'm unfamiliar with availability of flex track or sectional track with standard radii in S-scale, but, if you only have sectional track available in 24 inch radius and 27 inch radius curves and you use a 3 inch wide ramp under each, then your minimum footprint would be a 57 inch diameter circle. For ease of construction, this could be set on a 5x5 foot square base. With 2 foot wide aisles all around, this would occupy a 9x9 foot space.

    The footprint for 2 helixes set side by side would be 2 circles set side by side and each circle would have a diameter equal to:
    Radius of the track centerline times 2 plus 3 inches to the helix ramp's outside edge.
    For 24 inch radius curves, the footprint would be about 4.5 feet for each circle or about a 5x9 foot footprint. With 2 foot aisles around it on all sides, then your space would be 9x13!

    The footprint for a double tracked single helix would be approximately 6 inches wider and 6 inches longer than the 2 helixes set side by side because the teardrop shaped loop to reverse the track so the train can go back down the same ramp would occupy the same floor space as the 2nd helix and the ramp for the first helix would be 6 inches wide instead of 3 inches.

    The interesting constant motion will be most easily seen in the 2 side-by-side helixes because the inside tracks of the double tracked single helix and of the geniune double helix will be buried 4.5 inches deep and visible only through a (about) 3.5 to 4 inch high space. In the case of the genuine double helix, the inside ramp will be descending at an angle to the rising outside ramp and will only be completely visible at 2 points opposite each other on each loop. At all other points, the outside ramp will cover at least part of the inside ramp.
    Last edited by a moderator: Dec 26, 2008

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