I have a closet adjacent to my train room and I am planning to put a helix in there. The space is wide enough that I can use a 32" radius, but the it's about a foot deeper...so I could add some straight track on two sides, making the helix an oval. My question is, would adding this straight track make the operation of the helix better?
I belong to a model railroad club with two helix's. One is all round and one is a slight oval. I have seen no difference in how the train run. The only thing different is how it looks.
Perhaps not by much, but yes. First of all, it won't make it worse. Secondly, you can take advantage of this situation by making your grade slightly shallower, and you'll be able to run longer or heavier trains that way. That said, adding only a foot in between 32" curves is not a big difference.
More information, please Lynngrove: Oval helixes will function just as well as circular helixes. They even have the potential to function a slight bit better because the straight section provides some minor relief from the friction of pulling long strings of cars upward around a curve. You wrote: "The space is wide enough that I can use a 32" radius, but it's about a foot deeper..." A 32" track centerline radius means the outside radius of your helix ramp that makes each loop will need to be about 33.5" in HO and about 32.75" in N scale. This yields an outside helix diameter of 67'' or 65.5", so I assume the closet must be about 5'8" wide wall to wall. 1. Do you plan to put the entire helix inside the closet (meaning the closet is at least 6'8" deep)...or will half of the helix be in front of the closet (meaning the closet is closer to the typical closet depth of 3 or 4 feet and the closet doorway is about 5'8" wide)? 2. What are the exact dimensions of the closet walls and the closet doorway? 3. Please describe or post a picture of the floor plan of the room and walls so we can see where the closet is located with respect to the room walls, and where the helix will be with respect to the 2 (more?) layout decks it will be connecting. For what it's worth...some numbers and formulas to consider: A 32" radius loop has a 200.96" circumference (2 X Pi X Radius = 2 X 3.14 X 32 = 200.96). Assuming a 2% grade, a single 32" loop can rise about 4 inches (% Grade x Run = Rise = % Grade x Circumference = .02 x 200.96 = 4.0192 inches of rise in one loop). This will probably provide adequate clearance for HO if the thickness of the ramp is only 1/2 inch. If your helix ramp is thicker than 1/2 inch, then you may come close on clearance where the front end of a higher or longer car enters the lower end of the helix and starts up the grade while the back end of the car is still on the 0 inches elevation outside the helix. Adding 12" of straight track on 2 sides of the 32" radius helix will increase the length of a single loop by 24 inches, so you will be able to rise about another 1/2 inch farther in a single oval loop of the same grade. Rise = % grade x (Circumference + 24 inches) = 4.4992 inches of rise in one loop. This could potentially reduce the number of loops you need to move between 2 decks. If you decide to use the same number of loops, an oval loop of 32" radius and 224" circumference will let you rise the same distance at a lesser grade than a circular loop. Assuming 4 inches between the railheads on any two consecutive loops, % Grade = Rise divided by Run = 4 inches/224.96 = 1.778% grade up one oval loop compared to a 2 % grade up a circular loop. I have 4 bowl-shaped helixes (as opposed to the more common cylinder-shaped helixes) on my N-scale layout, 3 circular and 1 oval. All 4 are about 800 inches long and have a maximum grade of 2%. Go to My Albums linked in the signature block below to find helix pictures in the Helix album, Layout Tour album, and Layout Projects album. And page through the entries in my blog for more pictures and comments about helixes and helix construction.
HO scale. The closet is 71.75" wide and 85.5" deep. One 85.5" side is on the other side of the wall from the train room. One 71.75" side is open (no doorway) to the hallway. It had a bi-fold door, but I removed it to use elsewhere in the building, so now it's open. My lower level benchwork is going to be about 44" from the floor, so my thought is to remove the drywall on both sides of the wall between the closet and the train room, put the helix entirely inside the closet and then use backdrop to hide the helix. Access to the helix can be crawl under and stand up inside. Everything is in the planning stages, nothing is built yet...so I am exploring options. I'm the construction engineering type, about 2/3 of my plan is in my head and 1/3 on paper at this point.
