What a Challenger could really do...

[CAZEPHYR]

GP40-2

CAZEPHYR

timz

BigJim

Can I use an SD40-2?

If you do, don't bet on yourself.

With 15 cars 1005 tons, the 4-8-4 allegedly reached 75 in 5.02 minutes, 19400 ft. If the single-unit diesels can win any race, that's the one to try for, since the 4-8-4's weight disadvantage has the greatest effect.

Knowing the parameters of the bet is limited to the gearing speed of the diesel, change the top speed to at least 90 mph and see which engine will win.  After all, we are talking about a 1946 steam locomotive that was designed and put into service sixty four years ago and was designed to run at 90 mph or more on a passenger train against a 2009 freight locomotive that is geared for 75 mph.  They also were used in freight and did well in that asignment even with the 79" drivers. 

This one is a sure bet for the 4-8-4.

  Hardly a good comparison.   

CZ

I'll bet on the 4-8-4 too vs. a single AC44. On the other hand, a CSX AC6000, with the software enabled to let it run at 90-100 mph, would eat the Niagara for a lunch with that train.

 

The limit on the diesel speed is the gearing, not the software.   It would be an interesting match up for sure, but my money would still be on the 4-8-4.   

CZ

The picture below pacing the 2502 at up to 77 mph with a sixty five car banana train in 1954 shows steam at what it does best.  We paced this train for thirty miles or so north on Illinois 45 and watched as that locomotive just ate up the miles at speed.  I don't believe any single diesel today could have done the same speed as this locomotive could do.    

 

CZ

 

 

[GP40-2]

CAZEPHYR

...The limit on the diesel speed is the gearing, not the software...

You are still stuck in the DC traction motor era mindset on this. CSX's AC6000s are software limited to 75 MPH. With their current gearing, they would have to hit 110-115 mph before the AC motors are in any danger of over speeding. Whether or not you would want a locomotive with CSX's axle loading hitting 100+ is another story.

[GP40-2]

CAZEPHYR

The picture below pacing the 2502 at up to 77 mph with a sixty five car banana train in 1954 shows steam at what it does best.  We paced this train for thirty miles or so north on Illinois 45 and watched as that locomotive just ate up the miles at speed.  I don't believe any single diesel today could have done the same speed as this locomotive could do.    

Before you can make a statement like that, we would have to know what was the tonnage of the train, what was the gradient in that area, and what exactly is that locomotive in the picture. Without that information, comparisons to other locomotives, whether steam, diesel, or electrics are meaningless.

[CAZEPHYR]

GP40-2

CAZEPHYR

The picture below pacing the 2502 at up to 77 mph with a sixty five car banana train in 1954 shows steam at what it does best.  We paced this train for thirty miles or so north on Illinois 45 and watched as that locomotive just ate up the miles at speed.  I don't believe any single diesel today could have done the same speed as this locomotive could do.    

Before you can make a statement like that, we would have to know what was the tonnage of the train, what was the gradient in that area, and what exactly is that locomotive in the picture. Without that information, comparisons to other locomotives, whether steam, diesel, or electrics are meaningless.

You are correct about this conversation being meaningless.  We are discussing something that can never take place and to continue making a comparison is not productive.  Sorry I gave you an example of steam in action.  

CZ

[oltmannd]

CAZEPHYR

The picture below pacing the 2502 at up to 77 mph with a sixty five car banana train in 1954 shows steam at what it does best.  We paced this train for thirty miles or so north on Illinois 45 and watched as that locomotive just ate up the miles at speed.  I don't believe any single diesel today could have done the same speed as this locomotive could do.    

You are right. A single diesel locomotive cannot haul a 65 car, 3250 ton train a 77 mph on the level. It takes 10,000 HP to do that. 6000 HP would get you to 60 mph on the level. An AC6000 can do that.

HP is HP, steam or diesel doesn't matter. I don't know of any steam locomotive boilers rated at 10,000 HP, either.

[Redwards]

CZ,

 I love that banana train pacing shot - thanks for posting.  It reminded me of the signature picture from 'The Mohawk that Refused to Abdicate' where the Mohawk in question blasts past Morgan and Hastings.

--Reed

[CAZEPHYR]

Redwards

CZ,

 I love that banana train pacing shot - thanks for posting.  It reminded me of the signature picture from 'The Mohawk that Refused to Abdicate' where the Mohawk in question blasts past Morgan and Hastings.

--Reed

Reed

Thanks.  We got to see that train many times but only paced it one time at speeds like this.  

I have that book also by Morgan and Hastings and that story was repeated many times by different railroads in the early fifites.

CZ

[BigJim]

You are right. A single diesel locomotive cannot haul a 65 car, 3250 ton train a 77 mph on the level.

Initially we we talking about something 18 - 22 cars in the 1500 - 1800 ton range. Although it is a safe bet it will never happen, there is a very real possibility that a drag race between UP's finest AC44 and 3985 could take place. I have no idea, but, does not UP have some 79mph track to run on?

What is needed here is some input from a UP engineer who has run the big AC units and knows how they perform.

[GP40-2]

oltmannd

CAZEPHYR

The picture below pacing the 2502 at up to 77 mph with a sixty five car banana train in 1954 shows steam at what it does best.  We paced this train for thirty miles or so north on Illinois 45 and watched as that locomotive just ate up the miles at speed.  I don't believe any single diesel today could have done the same speed as this locomotive could do.    

You are right. A single diesel locomotive cannot haul a 65 car, 3250 ton train a 77 mph on the level. It takes 10,000 HP to do that. 6000 HP would get you to 60 mph on the level. An AC6000 can do that.

HP is HP, steam or diesel doesn't matter. I don't know of any steam locomotive boilers rated at 10,000 HP, either.

Good point on the total power required to move X amount of mass at Y mph. This is simple question of physics. Either that train was totally empty, or it wasn't 65 cars, or it wasn't traveling anywhere near 77 mph. That's the mathematical beauty of physics, it doesn't care whether the locomotive is steam or diesel like a railfan might. It just says a specific amount of power is needed to move a certain amount of mass at a specific speed. There is no way of getting around that.

[Anonymous]

Some additional infos about that 3985-APL run in '91:

Hope not repeating something, but in fact the run was,
with the one notable exception at Archer Hill, a downhill run.

The average speed of that train was in the upper forties.

Just look at the elevation at Cheyenne and North Platte. I think the constant loss over that distance is -0.25%.
I believe Tim has the most detailed plans about the track condition.

Another fact, does not have those multi-linked double-stack trains some general advantage in rolling resistance?
If not, why there were built like that... OK, some others, too, train length, less dead weight, etc.

Consider also that the engine was totally overhauled at that time,
burning oil and others advantages... I think all that helped to do the trick,
regardless it produced 4700 or 5000  DBHP. Delta is less than 10%,
that a fine estimation in my eyes.

Let a train like that running through sags,  
we might have even accelerated to nearly 70mph, for a short time.

A Challenger would not be good to pull constantly 7000 tons at a grade of 0.7%. The grade of 0.82%, was the most commonly used grade between Wahsatch and Cheyenne. A Chally was rated
4290tons, 1948- era friction wheels, considering an av. speed of 15-20mph.

There were 3 GE-Dash's, I think that is correct, that pulled the train into Cheyenne, than Chally took over it.
The Train it took back to Cheyenne, now running constly. 0.25% up, was much smaller, 1000tons, or so.

http://www.youtube.com/watch?v=GyZD7fJ12WI&feature=related

If anybody would like to have a sequence of the tape for more infos, post me, I digitized it.

What I want to say, seen from a overall performance, it is pretty that of an AC4400.

If you really want a mess, look at this...

http://www.youtube.com/watch?v=aoGBL0XFjQ8

 

Cheers

lars

[timz]

GP40-2

It just says a specific amount of power is needed to move a certain amount of mass at a specific speed.

On level track, you mean? No reason to assume the IC 4-8-2 was on the level.

But "physics" doesn't tell us anything specific about how much power is needed on the level. We need tests for that.

[Yardmaster01]

OK, so it only took the locomoive builders 50+ yrs. to come up with a DE that can equal "modern" steam on a unit for unit basis, I can live with that.  Now for a couple of other monkey wrenches, Dante Porta and ACE 3000.  What if? 

[selector]

Yardmaster01

OK, so it only took the locomoive builders 50+ yrs. to come up with a DE that can equal "modern" steam on a unit for unit basis...

Not to quibble, but it took them over 100 years in steam development to get to where they were at the point of the Challenger.  Diesels have been under development for about 70-ish.  We'll have to wait for three decades to see where the diesel crowd finds itself after the equivalent passage of time.

-Crandell

[GP40-2]

timz

On level track, you mean? No reason to assume the IC 4-8-2 was on the level.

Well, I guess it could be going downhill and getting a 6500 HP assist from gravity. Are the hills that big in that area?

timz

But "physics" doesn't tell us anything specific about how much power is needed on the level. We need tests for that.

I'm assuming by "tests", you mean data collection for the computations? Once you have that data on the locomotive and train forces, this is a very straight forward physics problem to repeatedly model.

[Grantham]

Even if we discount the size of the hills over the section of line that the train covers, it remains a very impressive train, hauled by a very impressive loco. It's great to see the lack of diesel assistance which indicates that the railway company either wants to prove the loco or at the very least, trusts it.

 

Great video!

[CSSHEGEWISCH]

Yardmaster01

OK, so it only took the locomoive builders 50+ yrs. to come up with a DE that can equal "modern" steam on a unit for unit basis, I can live with that.  Now for a couple of other monkey wrenches, Dante Porta and ACE 3000.  What if? 

Although it took while to get 4000+ HP in a single unit, multiple unit control renders that argument moot, ATSF was running 4-unit 5400 HP FT sets across the Arizona desert (without water stops) in 1944.  ACE 3000 is dormant, if not dead.  Dante Porta's designs may be in the same situation.  After all, Manchuria is the N&W of worldwide steam locomotion, which also means that the end is near for steam locomotives in regular service.

[timz]

GP40-2

timz

On level track, you mean? No reason to assume the IC 4-8-2 was on the level.

Well, I guess it could be going downhill and getting a 6500 HP assist from gravity. Are the hills that big in that area?

We can't rule out 0.4% down, which would supply that.

GP40-2

Once you have that data on the locomotive and train forces, this is a very straight forward physics problem to repeatedly model.

Correct-- once we have done the tests needed to find out how much power it takes to pull the train, then we know how much power it takes to pull the train. Until then, physics doesn't help (on level track).

[santafe5011]

HI i´m spanish and i have an vhs were you can see 3985 going full speed with that consist, i find the video on youtube so here it is https://www.youtube.com/watch?v=r_yHO0fZDaQ 

it starts at 22:30, it must have much more than 4700 dbh that people is saying, it´s going at least 65 mph if no more with a near 8000 ton train.