Your dream loco for Bachmann to produce

[Kevin Strong]

Harold, compare the distance from the forward driver to the cylinders on the converted 4-6-0 and the 4-4-0 in the drawing. The pilot truck is easily a full 1/2" farther forward on the model than on the loco in the drawing. Closing that gap to a more prototypic distance changes the geometry completely. I guarantee you that you can fit an On30 8-18-C around an 18" radius with room to spare. The geometry in play is linear. If a 1:20.3 model can fit around a 30" radius, then a model built to the same design that's less than half its size will fit around a radius that's proportionally identical in that given scale. (i.e, a 1:20 loco is to a 30" radius as a 1:48 version of that same loco is to a 12.5" radius.)

Later,

K

[hminky]

Nah! The Roundhouse HO 4-4-0 has problems on 18".

To talk about a 8-18-c:



The 4-4-0 plan in the first picture was a smaller 4-4-0. The above picture is the 55n3 4-4-0 compared to SPC #3. A Scale48 4-4-0 would be 15% bigger since Scale55 is 7/8 of Scale48.


Harold

EDIT: Both plans are Scale55

[Kevin Strong]

Harold, you're missing my point. Scale has nothing to do with the equation. It's all geometry. There are three points in play. The rear driven axle, the forward driven axle, and the front pilot. The rear two points are fixed, the front one has a degree of lateral play designed to get it around curves. The closer the distance between the forward driven axle and the front pilot, the less lateral swing there is needed on the front pilot truck. The greater that distance, the greater the lateral swing needed.

I'm not talking about what the Roundhouse or any other specific HO-scale locomotive may or may not be able to do. I'm talking specifically a geometry that's been mechanically shown to work, and translating that to 1:48.

Measuring the 1:20.3 4-4-0 that's on my shelf, there's 4" between the drivers, and 5" between the forward driver and center of the front truck. The front pilot has 1" of lateral swing, exclusive of the lateral play in the pilot wheels and the frame (arguably an additional 1/8" either way of center.) This is sufficient for the locomotive to negotiate a 30" radius curve. That's probably the far extreme of what it can do, but it can do it.

Now, enter those geometric points into any drawing program. Next, change the scale of the ruler on the drawing. The relationship of the points to one another doesn't change. Proportionally, they're the same distance from one to another. The distance between the front point and forward driver is still 1 1/4 the distance between the rear and forward driver. The lateral play of the front pilot is still 1/5 the distance between the pilot and forward driver. The only thing that's changed is the particular unit of distance being used to measure those distances.

Therefore, if the drawing is done with the 1:20 measurements, the resulting "maximum" curve would be 30". If you change the scale to 1:10, the resulting curve becomes 60". Make it 1:1, the resulting curve is 600". (Note that the prototype locomotive wouldn't have what would scale to 20+" of lateral play in the front pilot.) Reducing the scale to 1:48, the resulting curve is 12.5". Based on geometry, a locomotive built to the same plans as Bachmann's 1:20 8-18-C, but in 1:48 would be able to handle an 18" radius curve without issue because the demonstrated minimum would be much less.

Later,

K

[C.S.R.R. Manager]

I would like to see an On30 version of the Fort Wilderness Railroad locos and passenger cars, which were built by Walt Disney Imagineering in the 1970s, and ran on 30" gauge tracks.  While I really like the Disney paint scheme, a basic black version would also be cool.  Here is a photo of the Large Scale model:



These locos were slightly scaled down versions of 36" gauge Olomana, from Hawaii.  Which would also be a good choice.



manager

[C.S.R.R. Manager]

And to add to the 4-4-0 discussion, I really like the lines of this little HOn3 brass loco, as painted and detailed by John Olson, on the cover of the May 1977 Model Railroader.



manager

[ebtnut]

I'm pretty sure that the Olson loco is one of the old NWSL "Spartan" locos.  They did both a 4-4-0 and a 2-6-0 in HOn3 with the same superstructure, tender, etc.  They were tender drive, so didn't pull a lot.  They were low-cost, leaving it to the buyer to detail as they saw fit.  I have one squirreled away somewhere that I "modernized" as it might have appeared ca. 1920.  These are not to be confused with the On3 Spartans, which were models of specific Baldwin designs.   

[C.S.R.R. Manager]

Good eye, ebtnut.  The MR article describes the process of adding detail and painting the Spartan model.  I'm not sure what the exact prototype is, but I really like the proportions.

Then again, I bought the LS Bachmann 4-4-0 because I like the proportions.  Can't run it anywhere, but it's a brilliant piece of 3D art.

manager

[radar]

K-27 1st
c-19 or 21 2nd
How about a true On30 Mallet

[hminky]

How about a true On30 Mallet

[Tomcat]

As radar said:

1st:  K-27 including the 455 RGS post-wreck (just as Fn3 scale)
2nd: C&S 74 / RGS #74
3rd: The long awaited Heisler - to me: preferably a West Side Lumber Heisler...

No we won´t give up to pray for a H...... !!!!

Cheers, Tom

[MarK T]

I'd love to see a K-27 28, 36....
And let's not forget the 44, 45 & 70 ton diesels

[ChrisS]

NO!!!! dont say k..... i didnt make the curves on my layout big enough...... i dont want to have to rebuild.. cause i sure couldnt restrain myself from getting one of each

[ebtnut]

I would remind folks that MMI has done the K-27 and K-36 in both On3 and On30, at a price that would not be much more than what Bachmann would have to charge.  They also did the C-19, and have announced plans to do the C-16.  See the ad in the new NG&SL Gazette.

[Royce Wilson]

Then that leaves us with a Heisler and a 4-4-0 that everyone wants! and last but not least the RGS 20.


Royce

[Dusten Barefoot]

Or an inside frame 2-8-0.

Rock On!
Dusten