N Scale Helix Question

What is typically used as a radius for an N scale helix? I need something that will work reliably with long streamliner passenger trains.

Thanks,
Don

 

Plus it uses materials more efficiently! I like it.:thumbs_up:

 

:tb-ooh:I need to save this one so I don’t forget.
Glad the question was asked. I like it too. :thumbs_up:

 

there is a guy who sells a helix kit on EBay. I have one and it assembled quite easily. Let me know if that is the route that you might want to take, and I'll find his store.

 

I am about to start construction of a double track helix on my layout. The inner track radius is 15" while the outer is 16.5". Each turn has a rise of 2.5". I was originally going to build this as a circular helix, which would have resulted in a pretty steep grade of 2.7% on the inner track. But based on feedback from the forum here, I have decided to insert 18" long straight sections into the helix, changing it from a circle to an oval. This will result in a more pleasant grade of 1.5% on the inner track and also reduce friction between wheels & rails as the locos & cars traverse the straight sections. I am hoping to start building this in the next few weeks and I should have some drawings posted on here before then. Jamie

 

I know some people build an oval helix.

 

Don, my helix is a constant 22" radius. I would recommend you go as big as you can in the space you have. Like what was said in the previous posts, if you don't have alot of width, but have some length, then go with a straight section in between the end curves.


-Mike

 

I have two helii on my layout, both are on 4' x 4' square bases and are spiral like Hemi's and based on Ppinn's (Dave H) helix calculation sheet in the "sticky" at the top of the "layout design discusion" forum.



The radius minimum is 16" and spirals out to 22" at the top with a 2% grade.

Construction was easy enough for someone with basic carpentary skills


Both helii are open at the top and you can duck under and stand up inside the helix. Makes cleaning the rails a breeze as the tracks are not stacked one on top of the other. All this in a 11' x 9' spare bedroom. Opperationally, the radius works fine but I would go for less grade, maybe 1 1/2% if I were to start over again.

 

To answer the initial question, I don't think there is a "typical" radius used, but there would certainly be a minimum based on the trains you plan to run. I would float 15" as a "safe" minimum and 18" as something like "ideal for most people", unless you are blessed with loads of space and can do 24" or more. (Prototype minimum on such an arrangement, incidentally, would be something like 38" in N scale. But nevermind...)

Some rules of thumb...

-Try to get as low a grade and as high a radius as you can afford.
-The longer the trains, the lower the grade should be.
-The longer the trains, the higher the minimum radius should be.
-The lower the grade, the higher the minimum radius HAS to be (in a traditional helix).

-You usually need at least 2 1/4" difference from railhead to railhead in a traditional helix. That's 1 7/8" to clear superliners or stacks or racks, plus some height for roadbed, support, and track.

At a 2 percent grade, that comes to about an 18" radius. At a 2.5 percent grade (which is pushing it, IMO) that would be 14.5 inches. (I'm rounding up to the nearest half-inch.)

Many people would advise a 15" minimum radius and max 2 percent grade for any bigger-than-a-table layout, in any case. That is, if you're going to run trains longer than, say, 5 feet.

There are a lot of advantages to the spiral helix, as shown in this thread. It's easier to build, less wasteful, and the overhead clearance is not an issue for either grade calculations or cleaning and such. The disadvantage, as I see it, is that you might end up using a smaller radius at one end than you might actually have space for.

 

I’m so glad that you posted this information about the grade and height. :thumbs_up: I was trying to find this info to add to my notes. Thanks :tb-cool:

 

Argh I wish I could use a spiral helix in my design! Alas I just can't make it work. Not that I don't think my design will not work, but that spiral concept is just so simple and results in so little waste--there will be one on my next layout!

 

Pyramid helix

In one of the first issues of N-Scale was the design for a pyramid helix. Much like the bowl helix above, but upside down. The helix gets smaller as it climbs, but the grade gets less. It works well on my layout and sits under a mountain. The challenge is getting the supports cut the right length to get the grade right. I have a catch net under the helix "just in case". Much easier on a derailed loco than the floor!

Dave G
Cache Valley & Northern RR

 

I was thinking about doing this myself to save space by having an open side as the side of a mountain with portals on each level. That way I could have access from the sides instead of going down through the top or up from the bottom.

 

Helix

I am building a n gauge layout in my appartment. I have very limited space. I will have a board the width of 30in. I am looking to run double tracks three if possiable.
there will be one helix on both sides of the board for upper and lower levels. Both upper and lower levels will be about 11 feet long 30 in wide. I hope this helps.

Kenny

 

I built my oval helix with a 1.3% grade with a 15 inch inside radius on one end and 12 inch on the other with a 5 foot straight section. Thus it is only 3 laps. I am fortunate that the oval helix is in the adjacent furnace room. The center is open for complete access to all of the track. It is double track and built with 3/8 plywood and separated by threaded rod on the inside and outside. A little expensive but I felt the ease of adjustment and assembly was well worth it. I am easily running Walther Proto berkshires with 25 to 30 cars with no problems. I will try to add a photo or 2 later.

Jack Sibold

 

I use a 16" radius 2.5-level helix. It has a circumference of 100", climbs at a 2% grade gaining 2" per level, and yields a 1.5" overhead clearance above the railhead. This leaves only .5" for the structure, roadbed, and track (which is therefore more complicated). I can access it from inside for cleaning, and plan to implement some sort of safety net scheme to catch falling equipment, or maybe hot-glue little side walls on the sub-roadbed.

The spiral helices you guys mention above are a much more elegant solution, but I didn't have the space for anything over 16" radius.

MH

 

How did you cut the plywood and what is the plywood radius?
Kenny