@AGHRMatt posted:This is a general formula.
Measure from center to center on the trucks. Multiply that by three to get the minimum. Multiply by four (or more) for better appearance. For hi-rail cars you can usually get away with something smaller than the minimum, but it depends on how, closely the cars are coupled and how much swing they have.
That's close to what I was taught Matt. 3x the length of the entire car for reliable operation (some will go to 2.5x), 4x to look reasonable, and 5x to look really good and be able to couple body mounted Kadees on a curve.
That works out to the following for 21" cars:
- 2.5x= 52.5"r or O-105
- 3x= 63"r or O-126
- 4x= 84"r or O-168
- 5x= 105"r or O-210
This is why the shorter cars exist. It's really difficult to make passenger cars look realistic on curves in O scale. I struggle with this myself because it really bugs me when the diaphragms don't touch and when the cars open so wide on curves that people would fall between the cars if they tried to cross.
There are ways to mitigate the visual impact. In the past I've had good results with the following:
- Keep track level as close to eye level as possible. Ie. don't look down on trains
- Keep the viewer on the inside of tighter curves
- Limit or do away with viewing curves from the outside
- Use tunnels and/or view blocks for tight curves that the cars will go around but look bad on
- One good way to "test" how cars will look is to use N scale as a mock-up. Full length cars are a little over 6". Lay out a 30"r curve and put a couple cars on it and see how much better they look.
Just some tips I've learned from the experts over the years. Hope it helps.
