cuyama I notice that everyone is answering the question from eleven years ago, and not addressing the newcomer’s posting that resurrected the thread.
I notice that everyone is answering the question from eleven years ago, and not addressing the newcomer’s posting that resurrected the thread.
Modus operandi for this forum - and guilty as charged.
osgoodp73 I have a Rivarossi big Boy and I have been able to successfully run 4001 on a 22 inch radius, I am currently designing a helix for my home that will encompass from basement to 2nd story, I only have about a 4 ft dead space to accomplish this.... anyone have plans for a helix, ? I checked the calculator, and it is putting me at a 2.8% grade but only gives me a 96 inch plan That, unfortunately, is an idea that won’t work well. Curves on grades increase the effective gradient substantially, especially tighter curves such as 22” radius in HO. The rule-of-thumb for the additional effective grade is 32/R, “R” being the nominal grade. This would add about 1.5% to the nominal grade.
osgoodp73 I have a Rivarossi big Boy and I have been able to successfully run 4001 on a 22 inch radius, I am currently designing a helix for my home that will encompass from basement to 2nd story, I only have about a 4 ft dead space to accomplish this.... anyone have plans for a helix, ? I checked the calculator, and it is putting me at a 2.8% grade but only gives me a 96 inch plan
That, unfortunately, is an idea that won’t work well. Curves on grades increase the effective gradient substantially, especially tighter curves such as 22” radius in HO. The rule-of-thumb for the additional effective grade is 32/R, “R” being the nominal grade. This would add about 1.5% to the nominal grade.
Helixes are a major space hog which is what led me to go with a no-lix in my rather small space, plus they are rather complex to build. As you noted, it's a strict trade-off between radius and grade - tighter radius = steeper grade. OP stated 48-inches of dead space implying curve radii have to fit inside of that implying to me max curve radii would have to be no more than about 22-inches - not pretty for a helix.
If I did my math right, allowing for a bare minimum rise of 4-inches per turn(assuming 1 inch of track and subroadbed in the helix and 3-inches clearance) a 22-inch radius curve in the helix would be ~138 inches length per turn (2 x Pi x radius). Grade being rise/run divide 4 by 138 and get about 2.9% grade in a helix that tight.
More importantly, the Big Boy model is unlikely to work well when coupled to a train on a curved helix of that radius. The extra friction of the curves creates a tendency for the train to “stringline” – that is, to derail across the center of the curve. Even with less-demanding engines than a Big Boy, experienced modelers have found that multi-turn HO helixes work better at broader radii like 28-30” and beyond. Best of luck with your layout, but this is an idea that is not practical.
Best of luck with your layout, but this is an idea that is not practical.
Agree. Tight radius and steep grade there would be a lot of drag and tendency to stringline. Just not workable unless you plan on running short trains of short rolling stock.
Rio Grande. The Action Road - Focus 1977-1983
osgoodp73Hi everyone, lifetime hobbyist, I have a Rivarossi big Boy and I have been able to successfully run 4001 on a 22 inch radius, I am currently designing a helix for my home that will encompass from basement to 2nd story, I only have about a 4 ft dead space to accomplish this.... anyone have plans for a helix, ? I checked the calculator, and it is putting me at a 2.8% grade but only gives me a 96 inch plan
wjstix OK wait a minute...you're building a helix to connect the basement to the second story of the house?? So like from the basement to the attic??
riogrande5761Yes, that was a what the heck moment for me too. It's one thing to gain a couple feet by helix, but lets do the math say to go up two full floors - say 9 feet per level.
This would also seem to me to require holes/replacement floor supports for two set of floor joists. this seem to require an experienced, brave man. No advice from me, I could not do it.
Dave
selectorWhen there was any doubt, or when the crew and yarders knew a given locomotive might derail due to tight curves, people walked beside the locomotive while it edged around the curve, keeping an eye. They watched for lifting wheels. They did this when they last moved UP 9000 along the main to get it to CA in the 50's if I recall. I have a steam calendar with a photo of this event.
Hey, TZ. Yup, one of my favourite historical rail photos, even though it was at the very end of steam and comparatively modern. Who couldn't admire those twin flying pumps, the obviously looooonnnnng boiler, and all those drivers that looked like it was a foobie...impossible for a steamer to have that many driver axles!!! Very focused and careful walkers looking for the earliest signs of an impending derailment as the loco rounded the curve, but on the wider crossover.
-Crandell