ATSF 2-10-10-2

Depends on what you mean by 'powerful'! Power is the RATE of doing WORK. The AE's could surely do work, but they were too slow to produce a lot of power.

The VGN AE's had the greatest tractive effort of any steam loco except the four Triplexes (1 VGN, 3 Erie).

In POWER, however, meaning horsepower, they were nowhere close to several of the later locomotives like the Challengers, Big Boys, or Alleghenies, or the rigid-framed PRR Q2. Power is mainly determined by the firebox, and the AE's (and more so, the Triplexes) had relatively small fireboxes. This was typical of most locomotives of their day. Still, the AE was a big improvement over the earlier Triplex in this regard.

Let's not restart the 'biggest' steam loco fracas again ... at least for a while.

Dan Mitchell ==========

Capta>

They existed. I have a brass model of one that was imported by Westside Model Co. in the latter '70s. It was the test engine to determine how small of a mainline minimum radius and separation on curves I could use for the layout I'm planning.

Yeahbbut the triplexes were not successful. They could not produce steam sufficient to maintain steady service.

What I meant was in the tractive effort, or train pulling area. True, the Virginian did not run fast, but they used a single AE to pull trains of weights that required five or six SD-45s to pull, albeit the SD-45s DID run at a higher speed. Even so a single SD-45 could not possibly do the job even with 65/12 gearing, which would put it at about 30 MPH top speed. It would still require at least two of them to haul a

15,000 ton train over identical terrain at a fast walk.

Which is about the speed the AEs operated from what I hear At ten MPH average speed that's only a day and a half from Deepwater to Lambert's Point. Coal doesn't spoil.

Captain Handbrake

It's quite impressive to watch all of those drivers churning 'round and 'round. I set up some flex track on a sheet of plywood to determine the minimum radius to use on my layout in order to accommodate this engine. I came up with 89 cm (about 35") with a parallel track separation of 5 cm to avoid sideswiping. I'm having fits trying to plan a layout to accommodate those broad curves in my narrow layout room though.

Those "broad" curves are approximately equivalent to 23 degree curves, sharp for an industrial switcher and near the limit of a GP9 not coupled. Such a curve would be found in a tightly restricted industrial switching area, never on a mainline of a major railroad. A 79" radius curve would be approximately equivalent to a 10 degree curve on the prototype, which is typically considered sharp and usually restricted to speeds in the 30 MPH region. Such are the limits of our modeling. In actual practice, 35" radius curves work pretty good on a model railroad.

Captain Handbrake

It's certainly true that a single SD45 is not anywhere near the equal of a VGN AE in tractive effort. It probably has similar horsepower, however. The problem is USING the power at the slow speeds needed for a coal train, especially in the W.W.I time frame.

The last of the big steamers, Alleghenies, and the PRR Q2 were getting VERY close to 8000 hp. That's two and a half SD45's in 'power' terms. Such steamers were also VERY heavy, and that translated to a lot of tractive effort, though the VGN AE and several other locos could best them at pure 'TE'. The VGN AE, with it's small firebox, did NOT produce 'power' in that league. I don't have the actual figures, but it was likely in the 3000-4000 hp. range, somewhat comparable to a single SD45. That was LOT of power in it's day, but no longer.

The nature of a steam loco, however, is that it's power increases more-or-less linearly with speed (until the boiler reaches it's limit). Power wise, they're pretty poor at speeds below their designed 'cruising' speed. Designers compensated for this with appropriate choice of driver diameter (to select the necessary 'cruising' speed). Engines needing high speed had big drivers ... but VERY poor performance at low speeds. Engines needing a lot of low speed power got small drivers (like the AE) ... with no substantial ability to move at higher speeds. Thus steam locos were highly specialized, and not very versatile ... one of their biggest problems.

A Diesel can produce what power it has over a much wider speed range, allowing it to be far more 'flexible' in usage.

Dan Mitchell ==========

Capta>

I can believe that easily enough!

My VGN AE runs quite happily on similar curves, with a bit less overhang. The club layout I normally run it on is double tracked, with

38" and 40" (inside and outside) curves. The loco will run fine on the inner track, but sideswipes trains (especially any long cars) on the outer track, so it, and other (properly) articulated steam, can only be operated on the outer track (they swing 'out'). Long cars are similarly confined to the inner track (they swing 'in').

We built the club modules with 2" track centers, as per the published module 'standards' we worked to back in the 1980's, and in retrospect it was a BAD decision. Most of our home layouts had curves far tighter than

30", so the 38" & 40" curves seemed really generous to us at the time. NOT SO! I'd now recommend at least 2.5" track centers even at THAT radius.

Otherwise, the track is excellent, it's nearly all hand-laid and looks and runs GREAT, so we have no plans at this time to tear it up and relay it. We just have to be a little careful of what we run where ... real railroads have to do the same.

Dan Mitchell ==========

Rick J>

Thanks for a very informative post.

Dan, it's interesting to read that you have used 2" track centres. As I have never modelled double track, and only have loops/sidings on relatively straight track - 84" radius or better - I have laid my track centres at the typical US prototype distance of 13 (scale) feet, or approximately 1 3/4". Some industrial sidings were laid at 12 scale foot centres. Anybody else done similar?

QUIT

Dan, it's interesting to read that you have used 2" track centres. As I have never modelled double track, and only have loops/sidings on relatively straight track - 84" radius or better - I have laid my track centres at the typical US prototype distance of 13 (scale) feet, or approximately 1 3/4". Some industrial sidings were laid at 12 scale foot centres. Anybody else done similar?

Dan, it's interesting to read that you have used 2" track centres. As I have never modelled double track, and only have loops/sidings on relatively straight track - 84" radius or better - I have laid my track centres at the typical US prototype distance of 13 (scale) feet, or approximately 1 3/4". Some industrial sidings were laid at 12 scale foot centres. Anybody else done similar?

Dan, it's interesting to read that you have used 2" track centres. As I have never modelled double track, and only have loops/sidings on relatively straight track - 84" radius or better - I have laid my track centres at the typical US prototype distance of 13 (scale) feet, or approximately 1 3/4". Some industrial sidings were laid at 12 scale foot centres. Anybody else done similar?

I know that this sounds silly, but don't they ever turn the other way? Otherwise, they would simply be going round a big loop.

dlm

If 1 3/4" track centers are scale, than the 2" we use is generous for straight track or prototype curves. Even the 40" radius curves we use on the club modular layout are VERY 'tight' for a protoype curve. So, the

2" track separation (center to center) is quite inadequate. That is what was published for the HO module standards at the time (NMRA proposal, an outgrowth of N-Track standards, before the standards were adopted). A number of other HO modular groups in our area also built to these standards, and have similar problems.

We SHOULD have done some testing before we laid the track. We ASSUMED (wrong) that the published standards would be sufficient. None of us had any prior experience with curves as large as 40", as most of our member's home layouts use 18" to 24" radius curves. The 40" seemed REALLY generous at the time. Hindsightis better than foresight! :-(

Still, it's NOT a 'disaster', or we'd correct the problem. It's just an annoyance, and some minor planning is needed to avoid sideswipes. We've learned to live with it. On the plus side, the close track centers LOOK good!

Dan Mitchell ==========

Mark Newt>

That's correct. The modular display layout in question IS just a big oval loop, 12 ft. X 20 ft., with double track main and a somewhat less perfectly oval winding inner branch line with about a 20" radius curve. So, overhangs are alwasy in the SAME direction.

Dan Mitchell ==========

Dan Merkel wrote:

On Wed, 26 May 2004 16:39:35 UTC, Mark Newton wrote: 2000

Mark,

The 2" figure is commonly used in the U.S. except on tight curves. It is about the smallest separation that allows normal fingers to reach down to rerail a car.

Oops! My goof. My minimum radii for double track mainline track curves will be 89 cm for the inside curve and 95 cm for the outside track - 6 cm of separation. I figure I can close it up to 5 cm separation (about 2") on tangent tracks.

That makes sense - although I suppose the ideal situation would be to not have derailments in the first place :-)

The prototype doesn't use huge fingers to rerail rolling stock!

I use scale track spacing in sidings as I already horribly foreshorten trackwork and widening spacings makes turnout formations look even less prototypical.

Regards, Greg.P.