BN7150What is the car length of this model? Is the basis for the RP20.1 just experience (a rule of thumb)?
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What is the car length of this model? Is the basis for the RP20.1 just experience (a rule of thumb)?
Kadee 50' PS-1 Cushion Underframe boxcar 9' P-S door stock#6312 (Product without coupler trip pins) 1196
rrebell The weight is for total weight so that car should weigh 3.75 oz if I did my math right. Now in this age you can choose which way to go. Some people over weight their cars for max drag, others under weight for max cars in a train, still others mix it up tp be more relistic and you have to know proper placement tp avoid a problem, your choise.The things available when the NMRA came up with this were a lot different than today and were ment for smooth operation at a time that the drag from trucks would always be be an important item to consider. This is still true of those who run sprung trucks ect. Some trucks you can get today you can easily blow down a length of track. I have some cars that will roll away on a very slight grade and others that just sit there based on the trucks and wheels they have.
The weight is for total weight so that car should weigh 3.75 oz if I did my math right. Now in this age you can choose which way to go. Some people over weight their cars for max drag, others under weight for max cars in a train, still others mix it up tp be more relistic and you have to know proper placement tp avoid a problem, your choise.The things available when the NMRA came up with this were a lot different than today and were ment for smooth operation at a time that the drag from trucks would always be be an important item to consider. This is still true of those who run sprung trucks ect. Some trucks you can get today you can easily blow down a length of track. I have some cars that will roll away on a very slight grade and others that just sit there based on the trucks and wheels they have.
Not sure I understand the sprung truck comment? I run sprung trucks on most of my freight cars and a percentage of my passenger cars.
Did many sprung trucks back in the day have poor rolling qualities? Sure. That was then.
I consider equalization particularly important for 4 wheel trucks.
I conducted consderable testing years ago to find a free rolling equalized/sprung truck.
The result, Kadee sprung trucks refitted with Intermountain wheelsets proved more free rolling than ANY rigid frame plastic truck. No matter truck turner tuneups, different wheel sets, the Kadee/Intermountain setup beats them all.
Car weight - I make sure my cars are at or slightly below the NMRA RP.
The Kadee metal trucks lower the center of gravity of the cars.
Lower center of gravity, and equalization work together for much better tracking with long trains, without making cars into heavy sleds.
A prime example of the benefit of metal trucks and metal wheelsets are my Athearn 50' piggybacks.
By simply adding the Kadee/Intermountain truck setup, the stock Athearn flat car and vans comes out at 4.3 oz, within .14 oz of the NMRA RP.
Sheldon
SeeYou190 rrebell Some people over weight their cars for max drag, others under weight for max cars in a train, still others mix it up tp be more relistic and you have to know proper placement tp avoid a problem, your choice. I find the NMRA Recommended Practice way too complicated. My system is simpler by far for freight cars: Less than 50 feet: 4 ounces 50 feet: 5 ounces More than 50 feet: 6 ounces I have had no problems with derailments or operational problems, ever. If I ever do get passenger car modelling underway, I will ask the experience available in here what is best to do for excellent operation. -Kevin
rrebell Some people over weight their cars for max drag, others under weight for max cars in a train, still others mix it up tp be more relistic and you have to know proper placement tp avoid a problem, your choice.
I find the NMRA Recommended Practice way too complicated.
My system is simpler by far for freight cars:
Less than 50 feet: 4 ounces
50 feet: 5 ounces
More than 50 feet: 6 ounces
I have had no problems with derailments or operational problems, ever.
If I ever do get passenger car modelling underway, I will ask the experience available in here what is best to do for excellent operation.
-Kevin
I use a similar system somebody on this forum suggested a number of years ago. One ounce of weight for every 10 scale feet. That translates well to my passenger car fleet. I have 72 footers which are weighted to 7 ounces and 80+ footers which are weighted to 8 ounces.
This system produces a slightly heavier car which I think reduces derailments. A 40 foot boxcar is 480 inches which in HO scale rounds out to 5.5 inches. The NMRA formula would call for a weight of 1 oz. + 2.75 oz. for a total weight of 3.75 oz. or .25 oz. less than the system I use. I find it works well for all lengths of cars. An 80 foot passenger car is 11 inches in HO scale so the recommended NMRA weight is 1 oz. + 5.5 oz. for a total of 6.5 oz., a full ounce and a half less than my system. My locos are powerful enough to pull my trains up the one grade on my mainline which is about 1.75%. Sometimes I add a helper for operational interest even though it's not really needed.
It did.
You are welcome, I hope my description of my "Weight Ruler" made sense as well
dbduck . . . that is the "finished" weight the car should weigh not how much to add...The amount to be added is the difference between the original weight of the car and the recommended weight of the car
. . . that is the "finished" weight the car should weigh not how much to add...The amount to be added is the difference between the original weight of the car and the recommended weight of the car
what I have done to make the calculation easier, I made a ruler marked off in inches however labeled each mark in "ounces" taking into consideration the 1+1/2 ounce per inch formula.
For example:: the 1" mark is labeled "1.5oz" 2" mark "2oz" 3" mark "2.5oz" all the way up to the 12" mark being "7 oz"
then all you have to do is place this ruler against a car and it will instantly tell you what the car should weigh according to the recommended practice
as others have stated, that is the "finished" weight the car should weigh not how much to add...The amount to be added is the difference between the original weight of the car and the recommended weight of the car
wt ruler by Paul John, on Flickr
Hello All,
Attuvian1Under the Recommended Practice in the title, NMRA suggests one ounce plus and additional half ounce for each inch of the particular car.
Whether or not you subscribe and/or adhere to NMRA RP-20.1 is not what the OP is questioning.
rrebellThe weight is for total weight so that car should weigh 3.75 oz. ...
The RP is for the total weight of the car, which for the OPs example is indeed 3.75 oz.
This can get tricky with flat cars and open-topped hoppers where the load(s) are added or removed- -thus increasing or decreasing the car's total weight.
In my opinion, this is where personal experience and preferences come into play with car weight.
Keep in mind this is a Recommended Practice and not a Standard; which all manufacturers need to follow for interoperability.
Hope this helps.
"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"
RP20.1 is not complicated if you pull out a sheet of graph paper and chart total weight on one axis and total length on the other. Calculate the weight for your most common car type and draw a slope from the O/O point in the bottom left corner.
Our layout has 30" minimum radius curves with easements and grades of less than 2 percent. We get good results with a NMRA RP+1 ounce formula, and don't weight anything more than 9 ounces. We don't run much in the way of passenger cars but do have TOFC and autorack traffic.
For HO, the NMRA recommended weight for all cars is one ounce plus another 1/2 and ounce for every inch of the car length. If the car weight meets this spec, no additional weight is required (or wanted). There is no concept of "base weight". Weight is weight. NMRA weight has always worked for me. I have had RTR cars that derailed all the time. Weighting them up to the NMRA recommended weight fixed that. In addition, you want all the cars in a train weighing about the same, give or take a bit for length. Other wise heavy cars will pull lighter cars off the track on curves. And longer cars need more weight. I'm cheap, I use a cheap kitchen spring scale to weigh my cars. The postal scales are more accurate but cost more. You can use anything for weights. I like sheet lead which I get from the lumberyead, they sell it as flashing for chimneys and such. Acrylic caulking compound will stick any kind of weight down good and hard. For lead weights, soak the lead in vinegar for 5 or 10 minutes to etch the surface and give the adhesive something to grab onto.
David Starr www.newsnorthwoods.blogspot.com
I've never seriously bothered with the NMRA's standards (not that I question them), but I prefer to make my own assumptions.
This Athearn 2-bay hopper...
weighs 2 ounces when empty...
...and 7.2 oz. loaded...
...while this much re-worked Athearn boxcar (one of eight)...
also weighs 7.2oz.
In the past, I have added extra weight into a number of Rivarossi passenger cars, to make them track better, but soon discovered that the "new" 15oz. total weight of each car, while making them track much better, also made short work of damaging both the plastic journal boxes and the axle-tips of the Kadee wheelsets.
If I'm running a train with a number of those lightweight empty hoppers, they're always at the back of the train...but if there are enough of them, derailments will still occur.
Wayne
rrebellSome people over weight their cars for max drag, others under weight for max cars in a train, still others mix it up tp be more relistic and you have to know proper placement tp avoid a problem, your choice.
Living the dream.
I woke up this morning suddenly confused by something that was obvious to me six months ago. Under the Recommended Practice in the title, NMRA suggests one ounce plus and additional half ounce for each inch of the particular car. I've always assumed that the first ounce is the initial, base weight to be installed, not a representation of the weight of the car itself before any weights are added. So, a 5.5" Intermountain reefer kit should get 1 + 2.5 ounces suitably fixed to the floor of car body (throwing out the exta half inch). Hope this is clear. Is this correct?
Thanks.
John