Not practical nor desirable

The problem with super-weighting the cars is that some cars can barely achieve NMRA weight as it is, and in fact some cannot even reach that weight.  We have some skeleton pole cars on the Sudbury Division, and even though they are solid pewter, they are about half an ounce light, and other than adding loads, there is no hope of adding more weight to the cars.  We have numerous other flat and gondola cars in similar situations, though they are at the correct weight, it was only barely possible to reach it.  Adding loads to such cars is possible and does add weight, but sometimes you want a car to run empty, and then what will you do?

Then the other issue is wheels and bearings.  The added weight will certainly increase bearing wear unless you add metal bearings to all your trucks.

On our club layout we operate 40 car freights with 3 or 4 diesel units up 30" radius helices, and we have to provide enough power to make it up the hill.  We don't need any cars extra heavy; all our units are there for a reason already.  It's just a good thing that those numbers of units were prototypical for the Cartier Sub back then.

Do it! Maybe the world will follow

Weight the cars to your liking.  Maybe you'll be a trend setter.

My thought on this is that

Will give it a trial

Thanks for the feedback all, certainly some food for thought.  I would be willing to experiment regards the added wear to bearings. The powertrains are already being tested on club layouts as was mentioned, where the extra power is really needed.  And regards to the flat, spline open load cars, I might just have to strictly follow the prototype practice about placing them near the rear of the train when empty.   

I need to choose what an appropriate length of train is for the layout, hence what the pulling capacity is for one loco. IE for my layout an MP15 for is good for say 12 cars, add enough weight to each until she starts to slip, and use that as a guideline.  

If I come across any major revelations, I will certainly post a follow up.

Standards

You can certainly go ahead and weight the cars as heavy as you like, but the NMRA standard works well for equipment reliabilty and there is certainly no need to change those.

Also, the ruling grade on a layout tends to be in the helices, which is probably steeper than any grades on the prototype area unless you're modelling the rocky mountains.

The reason why a helix is special

It's pretty well understood that when a train enters a curve, there's more drag. It's also easy to understand that a train on a grade has more drag.

What makes a helix special is it's both a curve and a grade - and to make it worse, a helix is often several train lengths.

This means there will be no other place on your layout with this much train drag. You may have a train length grade some where, but you probably don't have a train length curve any where except in a helix - and it's a curve on a stiff grade - the worst kind.

The more gradual the curve, the less drag. The more gradual the grade, the less drag.

To ease the drag problems of a helix, you will want to use a larger radius. But even the smallest helix is a space-eater - now we're talking about making the helix bigger, sheesh!

That's the challenge, and that's why I hate the helix. It's a necessary evil for most multideck designs, but if you're paying attention, you want any helix you put on your layout to have as large a radius and as gradual a grade as possible, and as few tiers as possible.

Helix

I know that a helix is not your favorite way to get train from one level to the next but I don't see I have nay real option at this point. So here is what I am going to have on my N-scale layout. The curves on the helix will be 17 to 17 1/2 inch radius and it will have to lift trains aproximately 15 to 18 inches between the levels. The trains will consist of 15 to 17 cars plus one or two SD70MAC/SD80MAC locomotives. I may also be using a caboose depending on whether there will be any backing maneuvers after climbing the helix. I don't anticipate the climb to be any more than 2% but I am not sure of that as I haven't yet worked out the dynamics of this.

Irv

Using Helix Calc

Using helix Calc.. a 17.5 inch helix rising 16 inches will require 7.25 turns at 2% for about 66 feet.. almost 2 scale miles..

Using a modified version of the "radius effect" formula from HO (32/R) for N (18/R) You will have the equivelent of a 3% grade. There will be a 2.2 inch seperation between levels which is tight... that leaves a little more then 0.54 inch for track and the helix material.

For 15 to 17 cars you will probably need 2-3 locomotives based on my experience with my friend's 2.5% (really almost 3% in some spots..) helix.

Chris

Irv, some thoughts ...

Irv:

First I would ask if you've mocked up or otherwise have tested your deck separation - in my experience, a deck separation as little as 12-13 inches actually works surprisingly well. A separation of 18 inches creates a lot of extra unnecessary helix tiers.

Second, is there any way you can use a grade on the lower level and/or the upper level to bring the two decks closer together near the helix? I used this trick on my HO Siskiyou Line and as a result my helix only needed two tiers to get to the upper deck. Sure the two decks are somewhat close together at that location, but by using grades on both decks, outside the helix, I was able to increase the separation quickly enough elsewhere that it wasn't a problem.

By using these tricks, I was able to minimize the helix pain to just two tiers. And to make the pain even less, after going around one tier, the train pops out into a mini-scene before disappearing back into the second tier.

You need to do everything you can to minimize this 2 scale miles of hidden trackage - and there are ways if you're willing to explore some options.

Hmmm.

I am willing to experiment, Joe. Nothing except the lower level is set in stone at this point. I had thought to hide my helix in a bridge as the area anticipated does have to rise as it does on the prototype I am following (The New York Connecting Railroad). This area is located in Queens, NY and crosses five bridges and a major body of water before crossing into the Bronx. To my mind this perfect for a long bridge. That bridge is called the Hellgate Bridge if you'ld like to look it up.

I have tried a nolix and find that I don't have sufficient width to do both a riser and show convincing actvity on the lower level in the space I have available even in N-Scale. My main line crosses through and over several yards that are shared with other railroads, notably MTA the Hudson and Atlantic and even with Amtrak by way of Sunnyside Yard. MTA is better known as the New York City Transit Authority/former Long Island Railroad which handles some freight traffic at the East New York and other yards in Brooklyn and Queens. The Hudson and Atlantic handles all freight to and from Long Island formerly handled by the Long Island Railroad. It also operates Maspeth Yard and handles car float operations in NY and NJ though it doesn't have anything to do with the pasrt that operates on the water. That is another which only owns the 2 remaining operating car floats and hires tugs to move them.

So here is my thinking at this point. The lower level will represent the line between Bay Ridge and the Queens end of the approaches to Hell Gate Bridge. The upper level will represent the Bronx and points north and east (i.e. Westchester County and Connecticut to New Haven). Thus I saw the helix as being the perfect place to insert a nice long distance run between the levels and by making this helix represent the bridge also make it somewhat realistic as well. But I am open to suggestions from more experienced heads in this. But l will need to post the rough track plan that has been running around in my brain for the last two months. Hopefully, I 'll get that done by Monday as an update of my blog here.

Irv

Deck separation

Acceptible deck separation depends on things like how high the decks are. As the upper deck rises it will impinge on the view of the lower deck less and less until when the bottom of the upper deck is at eye level it impinges not at all (of course now there's a problem with viewing the upper deck). So as the upper rises, the lower deck can get closer to it.

Also, is deck depth. The deeper the lower deck the more separation you'll need to see in there and to work in there. If you're going for a 12" or less deck separation then don't make the lower deck very deep or working on it will be a nightmare. If the depth of the lower deck is only a few inches you could squeeze deck separation down to 5 or 6 inches with out it being an issue. But if its gonna be 24" deep I'd say an 18" separation would be a minimum.

FWIW

Charlie