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The Physics of HO???

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The Physics of HO???
Posted by Anonymous on Thursday, December 13, 2001 3:00 PM
As this question will no doubt exemplify, i am just re-entering the world of model railroading and would like to know how I discover what seems to me as very basic information: specifically, what is an acceptable "radical grade" for the average HO train locomotive to negotiate while pulling rolling stock? I am in the planning stages for creating a "layout" and would like to know what the "edges of the envelope are" just so I do not violate them. I am certain there are other "tecnical" issues that need to be considered before I let my imagination run unbridled. Can anyone point me in the directions for this research? I will be appreciative (as well my grandchildren who wish me to get beyond the planning stages.)

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Posted by thirdrail1 on Thursday, December 13, 2001 3:22 PM
I have never heard the phrase "radical grade", so do not know what is meant. But, although model trains can negotiate much sharper curves than the real thing (the 350 ft. minimum radius of industrial sidings is 48 1/4 inches in HO!), the same is not true about grades. The laws of physics still apply; halve the tonnage for each percent of grade, or 32 cars on the flat, 16 cars on 1 pct., 8 cars on 2 pct., 4 cars on 3 pct., 2 cars on 4 pct., 1 car on 5 pct. Five percent (1 inch in 20 inches) is about the steepest practical grade, model or prototype, but I would not have a main line grade over 1 in 40 or 2.5 percent.
"The public be ***ed, it's the Pennsylvania Railroad I'm competing with." - W.K.Vanderbilt
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Posted by rogerhensley on Friday, December 14, 2001 7:02 AM
I'm with Gregg. I have no idea what a you mean by radical grade. My recommendation as to grade is 2.5 to 3 percent. The effective grade will increase if you have a grade on a curve. Can you be a little more specific about exactly what you are asking?

Roger Hensley

Roger Hensley
= ECI Railroad - http://madisonrails.railfan.net/eci/eci_new.html =
= Railroads of Madison County - http://madisonrails.railfan.net/

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Posted by Anonymous on Friday, December 14, 2001 9:26 AM
I would suggest checking out the Subterrain System by Woodland Scenics.They offer flexible risers in two to four percent grades for elevation.Simple product to use and you don`t have to do the math! Gerald
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Posted by Anonymous on Friday, December 14, 2001 7:06 PM
Hi Whit,
For 'short' trains (4-6 cars), I'd stay with the previously mentioned 2.5 to 3% grade. Of course, one could always employ "helper" service. Know what I mean, wink,wink...Jeff
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Posted by Anonymous on Saturday, December 15, 2001 10:22 AM
Whit;
We would suggest you pick up the books by John Armstrong on track planning and design. There is also an older book on benchwork either by Mr. Armstrong or Mr. Westscott(sp?). All are excellent and contain a plethora of design and operational information and research materials.
The laws of physics very much apply to model railrods. Grades, curve transitions, car weighting, etc. all have an effect on operating reliability and ultimately, your enjoyment. Good planning and careful consideration (although not so much you remain in the armchair modeler position) will be rewarded. The books mentioned will greatly assist you. Good Luck!
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Posted by Anonymous on Saturday, December 15, 2001 10:30 AM
Uhmmmm....no Jeff i do not know what is meant by "helper service." Indeed, I clearly have displayed my extreme naivete; perhaps someone can also point me to a glossary as part of my beginning education. I appreciate the trouble you, Gregg, Roger Hensley and Gerald have gone to to help.

I will attempt to make myself clearer (but as with mixing colors, I fear soon I will only acheive muddier). Simply put, i want to get as high as i can as quickly as i can (afterall, I am a product of the sixties!). If (and the IF is big) i am understanding everyones explanation re: grade to be one percent (for HO) is something like rising one inch per 40 inches of track length then I think I am enquiring about something else. Or, does it really take a little more than ten feet of track run to get an interesting length of freight up and over a train running below?

Hope this makes it clearer; thanks again everybody for the help. And please don't let me tax your patience with me.

Whit
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Posted by Anonymous on Saturday, December 15, 2001 10:36 AM
Hey Mark . . . (and whoever else is represented by the "we" in you suggestion) THANKS. I will go hunt these books because that does sound like just what i am searching for. My first hunt only revealed track plans with no explanation for me on how much I can modify those. What you suggest sounds great; again Thanks,
Whit









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Posted by thirdrail1 on Saturday, December 15, 2001 2:01 PM
No, Whit, one in forty is NOT one percent, one in 100 is! One in 40 is 2.5 percent, about the maximum for main line grades. Yes, Whit, it does take at least ten feet of HO track for one rail line to cross another! Train lengths are extremely limited by grades. A train might have one horsepower per ton (coal) to 3 HP per ton (intermodal). OTOH, an 18 wheeler has 10 HP per ton! Also, while there is 1/12 the friction between steel wheel and steel rail as there is between rubber tire and concrete, the factor of adhesion is much less as well. TRAINS CANNOT GO UP STEEP HILLS!
"The public be ***ed, it's the Pennsylvania Railroad I'm competing with." - W.K.Vanderbilt
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Posted by Anonymous on Sunday, December 16, 2001 7:13 AM
Thanks Gregg . . . (this is why i have rounded shoulders and a flat forehead) too much shouldering shrugging while wondering and questioning then once i comprehend, i slap my forehead!! Again, Thanks that did help and am finding that it all works well with the plans I am drawing (hope the mock-up model goes as well).
Your patience with me is appreciated.
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Posted by Anonymous on Sunday, December 16, 2001 11:21 PM
Whit,
Welcome back to model railroading. I don't quit see the complicatedness (if that is a word) in your original question that some of the others have answered. In asking about grades in percentages, in real life a one percent grade rises one foot every 100 ft. 2%= 2ft in 100 feet,3% is 3fett every 100 ft., and so on. I hope i made that a little clearer. HO scale is 1ft = 3.5mm or almost 1/8 inch. That is for the math part. If buy chance you had a good pubic library in your comunity, they very often have a decent selection of model roalroad books. I would check there first before purchasing one. Oh ya, helper service is using more than one engine to pull or push your train up a grade. Happy Modeling to you.....Jamie
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Posted by Anonymous on Monday, December 17, 2001 6:07 PM
Whit,

There is the other matter concerning 'Helper Service.' The short explanation is that railroads will add engines to trains to help them get over especially steep hills. If you want the long explanation, just ask.

Enjoy - Ed
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Posted by Anonymous on Tuesday, December 18, 2001 11:23 AM
Whit;
I had to deal with the same issues, one thing to remember: tracks can go DOWN as well as UP. So, you can have 5 feet of track rising up to the bridge and 5 feet dipping below the level of the main track - adding up to 10 feet or a 2.5% grade! I put 22" radius curves into the mix and that required that I re-do some of my track by lengthening the incline. Harder to do after the fact, but I am resourceful. Also, make sure the rest of the track is really level first, otherwise you wind up with 2% in one direction and 3% in the other. That can be OK, but you cannot pull the same length train with the same number of engines. Adding engines is difficult even if bought from the same manufacturer, due to different running speeds. DCC can make this easier, I hear. You can pull more cars by lubing your axles with graphite powder (not oil!) I'll try that soon. I would like to run more than ten 40 foot cars with my small steamers.
I used Atlas' Right Track software to do my track planning, it's availble for free download. You are kind of limited to 18 or 22" curves (or flextrack - hard to guess the radius) and #4 or #6 turnouts. On the other hand, the double slip switches and curved turnouts are expensive, and you can approximate track and makes adjustements when you are laying real track. I had to go to 20.5" in one area, no problem, just lay out an 18" curve and splice in a short straight to stand in for those extra 2 1/2". Then, lay flextrack at the real 20 1/2" radius.
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Posted by Anonymous on Sunday, December 30, 2001 5:29 PM
Is speed important, another way is to regear your engines and make them heavier (careful here).
Have fun and try anything to get what you want FUN..
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Posted by Anonymous on Friday, January 4, 2002 8:25 PM
Let me second the recommendation about John Armstrong's books, particularly "Track Planning for Realistic Operation" It's got more useful, easy to understand information on grades, minimum radius curves, turnouts and other things which make the difference between fun and frustration than any other single source I've found. The areas in which I followed Mr. Armstrong's advice work fine. I'm changing the other areas, and they will be fine. But it would have been easier to do it right the first time.
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Posted by Anonymous on Sunday, January 6, 2002 7:57 PM
Whit;
The assumtion is that you are modeling (planning to) a mainline railroad. The answers you have received are correct. But if as I am, you are modeling a logging/mining railroad your grades most likely will be steeper. Geard locos (Shays) tend to be able to handle steeper grades, 5 to 8%. Also the train lengths tend to be shorter. An additional consideration is available space.

This wasn't to add confusion but to possibly clarify for others who read these postings.

Walt

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