BigJim The net traction HP is the same at 70 mph as it is at 10 mph. The only thing changing is the rolling resistance and air resistance at 70 mph, HP for traction may not change but Tractive Effort certainly does.
The net traction HP is the same at 70 mph as it is at 10 mph. The only thing changing is the rolling resistance and air resistance at 70 mph,
HP for traction may not change but Tractive Effort certainly does.
Never said it didn't.
So your point is exactly what?
GP40-2 BigJim: The net traction HP is the same at 70 mph as it is at 10 mph. The only thing changing is the rolling resistance and air resistance at 70 mph, HP for traction may not change but Tractive Effort certainly does. Never said it didn't. So your point is exactly what?
BigJim: The net traction HP is the same at 70 mph as it is at 10 mph. The only thing changing is the rolling resistance and air resistance at 70 mph, HP for traction may not change but Tractive Effort certainly does.
Basic physics rule the day here.
Power = force (tractive effort) x speed.
Where you have constant power (diesel locomotive), as speed goes down, force goes up.
Where you have constant force (steam locomotive), as speed goes down, power goes down.
In frt RRing today, where there is huge emphasis on fuel economy, RRs are generally dispatching on the drag rating of the power and living with the resultant running times. Even if you had a steam locomotive with the same tonnage rating as a diesel electric AND it the specific cost for fuel was equivalent ($/ft-lb), the diesel electric would still win the contest. The lower avg HP/ton would mean fewer ft-lbs of work to get the train over the road.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
GP40-2 ... Seems pretty shady for you to represent a GE product in your presentation, when you publicly admit you have no actual data on said product. ...
... Seems pretty shady for you to represent a GE product in your presentation, when you publicly admit you have no actual data on said product.
...
GP40-2: The graphic is just a representative graphic. RTC: Berkeley Simulation Software's Railroad Traffic Controller is preloaded with the GE locomotive in it and many other diesels as well. So the RTC comparison was based on industry data and not data I had to estimate.
John Rhodes
LDPorta At one point the Starting and Continous Tractive Effort ratings where listed for both the GE ES44AC and DC on GE's website. This is what I used, however the information appears to not be listed anymore.
At one point the Starting and Continous Tractive Effort ratings where listed for both the GE ES44AC and DC on GE's website. This is what I used, however the information appears to not be listed anymore.
Oh, I almost forgot the best part.
You see John, GE Transportation in is constantly being contacted by "railfans" wanting to know every detail of the current operation. Stuff like Engineering, performance, and financial data that GE only shares with actual customers. Well, they got so tired of the constant phone calls and e-mails, PR decided to put a Railfan information section on Transportation's web page. The only problem was it is GE Corporate policy not to discuss performance data on current industrial products (such as the ES Series) other than with a customer. So, some "information" was put up on the ES, but nobody said it had to be accurate, actual customer test driven data.
I hope you really didn't use that stuff for a professional presentation, because that was not its intent. After a while, it was decided keeping that part of the web site was just too much work, especially since it had nothing to do with customer service, and the whole thing was pulled down.
LDPorta The graphic is just a representative graphic. John Rhodes
The graphic is just a representative graphic.
What good is a "representative graphic" when it doesn't really represent the performance of an actual ES44AC, especially at high speed?
Also, the "representative graphic" for the 2-8-8-2 is based on a locomotive that has never existed.
And somehow your don't see a problem in any of this?
oltmannd Basic physics rule the day here. Power = force (tractive effort) x speed. Where you have constant power (diesel locomotive), as speed goes down, force goes up. Where you have constant force (steam locomotive), as speed goes down, power goes down. In frt RRing today, where there is huge emphasis on fuel economy, RRs are generally dispatching on the drag rating of the power and living with the resultant running times. Even if you had a steam locomotive with the same tonnage rating as a diesel electric AND it the specific cost for fuel was equivalent ($/ft-lb), the diesel electric would still win the contest. The lower avg HP/ton would mean fewer ft-lbs of work to get the train over the road.
You and I both know this. But to some people this steam vs. diesel-electric thing is a religion. Either you a a drinker of the Kool-Aid, or you are an infidel non-believer.
We are both just wasting our time trying to explain any of this.
One last thing John.
I do for the apologize for the first post. That's why I edited out my comments. However, I don't agree with your presentation or the methodology in it. I'm just leaving it at that and will not comment on any further posting on this subject.
Have a good evening.
Like I said in another post, HP can be expressed in many a form and to many a newbie you can BS your mechanical engineer way to stardom. Then again you can't fool all of the people all of the time.
.
BigJim Like I said in another post, HP can be expressed in many a form and to many a newbie you can BS your mechanical engineer way to stardom. Then again you can't fool all of the people all of the time.
What's with the attitude tonight, Jimbo. Didn't the NS supply you with enough Krispi Kremes while you hardly worked today?
GP40-2 Oh, I almost forgot the best part. You see John, GE Transportation in is constantly being contacted by "railfans" wanting to know every detail of the current operation. Stuff like Engineering, performance, and financial data that GE only shares with actual customers.
You see John, GE Transportation in is constantly being contacted by "railfans" wanting to know every detail of the current operation. Stuff like Engineering, performance, and financial data that GE only shares with actual customers.
Well Railfans,
He did forget the best part!
The part good ol' GP40 left out is that a GE 4 stroker takes almost a minute to build enough amps to get out of its own way. By then the EMD's have said bye-bye! In other words knock those GE's out of DB running 40mph at the bottom of a dip and open them up and they will be hard pressed to run 30 near the top of the hill. Do the same with an EMD and you are still running 40 at the top.
I hope this thread gets back into a useful discussion soon.
Crandell
GP40-2 One last thing John. I do for the apologize for the first post. That's why I edited out my comments. ... Have a good evening.
I do for the apologize for the first post. That's why I edited out my comments.
Apology accepted, no hard feelings. You have a good one. John R.
Some railroads are dispatching some trains based primarily on fuel economy. But not all railroads all trains. Intermodel and those railroads that are both intermodel heavy and approximate a one-speed operation figure heavily in the overall picture. Despite rising fuel costs, crew wages and interest and/or depreciation on rolling stock capital costs are still a major expense.
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