Polar Express Helix Minimum

[prrstation]

Bob,

Thanks so much for your diligence in offering a workable track framework for recreating the Polar Express mountain.

Request:
Can anyone who uses the RRTracks program (http://www.rrtrack.com/) provide a visual diagram of how to implement this design?

Thanks.

[lionelsoni]

For what it's worth, I have been playing with making the tightest possible spiral helix with Fastrack, with O48 for the widest circle.  Here's what I have, with the sections listed in order from bottom (outside) to top (inside):

9 O48 curves
3" straight
2 O36 curves
7.25" straight
1 O36 curve
2.5" straight
1 O36 curve
2.5" straight
1 O36 curve
2.5" straight
1 O36 curve
2.5" straight
1 O36 curve
2.5" straight
1 O36 curve
1.25" straight
2 O36 curves
3" straight
6 O36 curves

This yields only 2 3/4 turns, with about 3" track spacing.  If a descending helix is desired in the center, there are only 1 3/4 useful turns, because the inner, O36, turn must be the first (and probably the only) descending turn.

[jprampolla]

Hi Nornand Folks,

     Here are 4 links to a few YouTube vids that may be helpful.  These people did the helix in either the Fastrack or O27.  Seems they solved some of the problems you are thinking about.

https://www.youtube.com/watch?v=UjydzxRI1jA

https://www.youtube.com/watch?v=THgzoLsn-R8

https://www.youtube.com/watch?v=Mo5VYpBE0KE

https://www.youtube.com/watch?v=dJgM_gKSFOI

 

     Hope this helps!

Take care, Joe.

 

 

[lion88roar]

The 'helix' on a mountain should never cross itself (no two levels should ever be above another).

Therefore to get 4 'levels' as in the movie, I would start with O72, to O60, to O48 to O36 you do not need full circles of any other than the O36, if you want the descent to be inside the mountain you can use O36 curves, and just add some short straights as you descend.

[prrstation]

Your ambition to recreate the Polar Express mountain is admirable.

However, without knowing the precise dimentions of your proposed layout makes it difficult to offer suggestions of how to help you create it.

The attached photo shows the Polar Express four level mountain with a simulation of the "size" of Lionel's Polar Express train set.

Yes, the mountain and the ability to compress the four track levels to two can be done, but it will require various trial-and-error configurations to achieve it.

You need to determine the minimal diameter that the Polar Express locomotive can navigate.  That will be the highest point of the mountain track.

The second lowest track level should be no steeper than a three percent grade... as should each of the others if you choose to recreate the actual mountain depicted in the Polar Express movie.

Lionel's Polar Express locomotive has rubber traction tires, so navigating a three percent grade with the original three Polar Express passenger cars should not be a problem.

However, if you attempt to duplicate the actual five Polar Express passenger cars as shown in the movie, a two percent grade is more advisable.

Keep us informed of your progress.

[dbaker48]

I would strongly suggest that you may want to try a simple test before you start building.  I do NOT think you engine will be able to negotiate a 3 degree grade, much less a curved one.  I would just take some straight track and simulate the various grades over a 3 or 4 foot section, longer would be better.  And, then start adding cars and see how the engine performs pulling them up the straight section.  (You could use practically anything to support the "ramp" that you use for testing.)  Unfortunately, I think you may be disappointed with the results.

[lionelsoni]

J, once the train has gone through the O48 loop and the O36 loop, it needs to cross both loops to get out of the helix; and, since the O36 loop is only one loop behind, one of the tracks below is just as close as if the entire helix was made from O36.

[normivey]

Thanks to all for your replies and suggestions. As it works out, I have re-negotiated terms with SWMBO, and I am getting about half of the garage, and I'll have more space--I'll be able to use 60" curves, which I am confident the locomotive will climb easily.

[jwse30]

What I was trying to say,apparently unsucessfully, was that the lower loop of the helix would be o48 followed by an upper loop of o36, so the train would go around twice before having to cross the track below. The loop of 36 would be inside the 48 instead of directly above it. 

 

J White

 

[gvdobler]

J white

You only get once around in a helix to clear the track below, so the grade I mentioned is correct. Even switching to O36, you would still need to clear the track below. Switching to O36 would steepen the grade as you would still have clear the track below and you would have shortened the distance to do it in.

As I stated, Lionel has been climbing trestles in a figure 8 for a long time and had no trouble, so I think it would workout fine.

[rtraincollector]

Okay here is a contribitor that use to be here that mainly posts on the other O guage forum but only reason i'm bring the link over here ( please Bob and Carl don't yell to much  ) is it covers this topic as you will see has built one so he may be able to help you if you contact him http://ogrforum.ogaugerr.com/topic/my-dreamnightmare-layout--update-4913-helix-done-in-54-days?page=1 

[jwse30]

The 151" mentioned was for one lap around a circle of 48" curves. If you do two circles of 48" curves, the grade would be less, but there probably won't be enough height for the train to clear between the two circles. If you did a circle of 48" and then a circle of 36" to finish the climb, the grade would be less, and there should be enough clearance for the train to be able to go from one circle to the next. Perhaps making the grade a bit steeper on the bigger curves where the engine won't have to work quite as hard as it does on the sharper curves would help.

 

Just a few random thoughts. I've never built a helix before, so my ideas may be less than practical.

 

J White

 

[normivey]

I thought of this, and I do have some additional room in one direction, but I will only have access to the helix from one side. Even the 48 inch structure is going to make access difficult to the far side of the layout. I suppose I could make the center of the helix open and have duck-under access. I was hoping to put a mountain in the center of the helix to mimic the scene from the movie where the train encircles the peak as it climbs.

[lionelsoni]

Are you constrained in all directions to the 52 inches that O48 would limit you to?  Or could you stretch the helix into a 52-inch-wide oval?  With a 3-percent grade, each inch of straight track that you can add to each of the two sides of the oval will increase the rise per lap by about 1/16 inch above the 4 1/2-inch rise of a circular helix.  So, 8 inches gets you to a 5-inch rise, 16 inches to 5 1/2 inches, and 24 inches to 6 inches.

[normivey]

Thanks for the replay and guidance. I've read somewhere that the grade reduces the curve diameter that a train can negotiate, and that's what I'm concerned about.

At the top it runs off to a reversing loop and comes back down the same helix. At least that's the plan. I'm working with an awkward space.

 

[gvdobler]

If it came with 036, then it would run fine on 048. The question is how much of a hill (grade) are you wanting to use. The formula of 2" rise in 100" of travel yields a 2% grade, not enough to clear the bottom track. Most figure 8's on a trestle climb just fine and clear the track below, so measure it out. Someone here has experimented I'm sure. 

What do you do with it at the top?

PS: It is about 151" around an 048 circle. If you wanted it to climb 6" then divide 6" by 151" and you get about a 3.9% grade. Steep yes, but not imposssible.

[normivey]

I have the Lionel Polar Express with the 2-8-4 Berkshire locomotive. The set came with 036 curves, and it runs fine. I'm wanting to build a helix for it to climb 2 revolutions. Does anyone have experience that tells if this locomotive and cars will climb a Fastrack 048 helix? That's the maximum space I have available for it. Thanks in advance for your assistance.