S Curves

Rule of thumb is 10".  In the past I have just squeaked by with a 5" section.

What track are we using?

'S' curves are the bane of my existence.  Like you, my room limitations create the need to S curves in a couple of places.  I hate them, and unless they are extremely broad, they don't look good either.  Operationally, you'll get different answers, but in a perfect world I'd like to have the length of my longest consist piece - in my case that's either the length of a scale E-8 unit or an 18" passenger car.   Even half that is worth while - I find that especially with some steam locomotives, the front pilots like to "straighten" out before changing direction, and this is especially important with switches.  I've put as little as 5 inches in front of a switch and solved a derailment issue in the past.  

The good news is that if no switches are involved, most engines will take an 'S' as long as you stay within the recommended curve guidelines.  I think MTH, for example, rates their ability to traverse a rated 'S' curve in reverse.  If you buy an engine rated O-72, in theory it should run backwards through an O-72 'S' curve.  It may look absolutely horrible doing so, but it is what it is.  

I worry about it more at higher speeds.  My E-8s are rated at O-42 or less, and when I put them through an O-60 'S' curve, it really seems like a lot of stress on the couplers. At 60 SMPH, it would snap every neck in the passenger cars.   Not very prototypical to the eye, either.  I wish I had the room for some nice sweeping O-120 or O-180 curves, but that just isn't reality 

I have been going back and forth between using tubular Lionel track and Gargraves.  

It eases my mind to hear about 10" straights.  I think I can manage to have at least that much.

Would love to have minimum 0-72 radii, but I have a peninsula that is only 60" wide so I am limited to 0-54 to keep track on table.  

lckiii,

S-curves are a real concern in the 2- and 3-rail scale world where the couplers are mounted to the car body.  As thestumper stated, in this case you should have a straight section between the curves that is at least as long as your longest car.

In the 3-rail Highrail or toy world, where the couplers are attached to the truck, this is much less a concern because of the extra coupler swing you get.  Technically, you probably don't need a straight between the curves although my 21" K-Line passenger cars did not like going through O-60 S-curves on a friends layout (they are rated for O-54).  I would try to put the longest straight I could between the curves for esthetics as well as operational reasons.

The straight section should be the length of your longest car, so that the car can have both trucks on the straight section at the same time.

The straight section should be the same length as your longest car, but let's face it--sometimes that isn't possible.

In that case, any amount of straight track helps some, and sometimes inserting a half section of 072 on either side of whatever length of straight track on a 060 or 054 S curve will work wonders for operation, and also help the overall appearance, and still save the necessary real estate so the track will fit within the available space.

Jeff C

That's one of the beauties of 3 rail trains, they are a lot more forgiving. As others have said, one max car length between curves is ideal.

I will add a vote for the O-72 lead in and out on the curves, it makes a wonderful improvement in handling on all equipment.

I used a full O-72 section but I suppose a half section is far better than none.

And Yes, a 10" straight will make big difference as well.

Combine those for the best results.