Oh look, Michael and Tom and fighting again. I'm shocked.
Come on fellas, we're all adults here (for the most part, anyway). Can we try to behave in a civilized manner? Try not to nit-pick each other to death.
Bergie
Hugh Jampton wrote: user="BuyCSXrailroadStock!"] Greenbrier and Gunderson are making Light Wieght Aluminum Coal Cars.... Must be a reason for this. The fuel savings on a 100 car 10,000 ton freight train? Also I have seen Allunimun Hoppers....So it is only a a matter of time before we have Allnimim Intermodal Flats.. Not fuel savings. With coal for every pound you remove from the tare weight of the vehicle it allows an extra pound of coal, given that railroads are limited by the axle load.Intermodal cars don't even come close to reaching the limit, and until they rais the maximum load of a comtainer to the point where aluminum cars become necessary they'll be made of goos old cheaper steel.
user="BuyCSXrailroadStock!"] Greenbrier and Gunderson are making Light Wieght Aluminum Coal Cars.... Must be a reason for this. The fuel savings on a 100 car 10,000 ton freight train? Also I have seen Allunimun Hoppers....So it is only a a matter of time before we have Allnimim Intermodal Flats..
Greenbrier and Gunderson are making Light Wieght Aluminum Coal Cars....
Must be a reason for this. The fuel savings on a 100 car 10,000 ton freight train?
Also I have seen Allunimun Hoppers....So it is only a a matter of time before we have Allnimim Intermodal Flats..
True. The weight savings that comes from using aluminum over steel in intermodal apps is focussed on the boxes/trailers themselves, since highway weight limits do affect the cargo vs tare equation.
TomDiehl wrote: chad thomas wrote:With the same horsepower per ton at higher speeds the stacker will have higher wind resistance therefore the TOFC will be slower. Beyond that it's depends on many factors. A hotshot UPS Z train will get more HP/T then a stack train and would be faster. As big and heavy as any train is, the wind resistance is a very small factor. Dating back to the first streamliners, designers such as Lowey and Dreyfus used to refer to them as "Streamstyled" because they recognized this.
chad thomas wrote:With the same horsepower per ton at higher speeds the stacker will have higher wind resistance therefore the TOFC will be slower. Beyond that it's depends on many factors. A hotshot UPS Z train will get more HP/T then a stack train and would be faster.
As big and heavy as any train is, the wind resistance is a very small factor. Dating back to the first streamliners, designers such as Lowey and Dreyfus used to refer to them as "Streamstyled" because they recognized this.
Among the first six posts were the preceding.
Now, if train priority was the determining factor, it could have been a short thread.
However, if the first few comments suggested that "wind resistance" is or is not a factor that anyone wants to consider, then the proposition requires 1) recognition that aerodynamic drag is a significant factor and more so as the speed gets higher, and requires specific information about 2) the weight of the loaded car, 3) the cross section area of the car, 4) the resistance coefficient for the car type, 5) the number of and car types on the train, 6) knowledge that time tested industry-recognized algorithms exists which utilize that information to provide an answer to the questions/comments contained in the above posts.
In the case of TOFC, aerodynamic turbulence increases its aerodynamic resistance significantly beyond what its cross section area might suggest. It has an accordingly higher coefficient.
It did indeed take five pages to "discuss" those facets of the "question." I am gratified that two grown men who obviously didn't understand a shred of it were at least reduced to giggling fits between their fascination with episodes of the Jerry Springer show.
It took a discussion on aerodynamic drag to bring out the best in them.
MichaelSol wrote: Why would you think we have to spend "millions" to obtain real data? We run hundreds of trains per day systemwide. Christ, all the performance data we need is there for the taking Yup, lots of 120 mph streamlined freight trains out there, aren't there? You are making me giggle too much.Do grown men actually giggle?
Why would you think we have to spend "millions" to obtain real data? We run hundreds of trains per day systemwide. Christ, all the performance data we need is there for the taking
Yup, lots of 120 mph streamlined freight trains out there, aren't there?
You are making me giggle too much.
They don't have data on flying cows either. It would be about a useful as data on 120 MPH streamlined freight trains.
And you do induce giggles. In fact, you, Mr. Sol, deserve a title, an honor, and recognition. You are dubed Sir Michael Gigglesnort, the profound proponent of steam over diesel, the Milwuakee Road's Pacifric Coast Extension, the statement that the Milwaukee was in receivership because it had too much business, and other such giggle inducing foolishness
greyhounds wrote:So BNSF offeres different service levels at different prices. The highest service level is used by the most service sensative customers. UPS and perishable commodity truckers like Stevens Transport are examples. This freight moves TOFC on the BNSF. There are some extra steps with COFC that at least have the potential to slow things down. I recall the BNSF standard for this level of service as being 750 miles/day.
I think the fastest freight trains on the BNSF system are the trailer on flat car (TOFC) trains on UPS service because these trains run on a time-sensitive basis. These trains, in effect, are the direct descendants of the famous Santa Fe Super C service of the 1960's and 1970's.
You know, if Wabash National can figure out how to build a RoadRailer trailer that meets UPS' requirements, that could speed up UPS trains even faster since RoadRailers eliminate the step of having to physically load and unload the trailer off the spline car.
Remember these questions from school?
A hot TOFC (piggyback/trailer) train with +3.0 hpt leaves Los Angeles at the exact same time as a medium priority COFC (container) train with 2-3 hpt and they each train travels east to Chicago at a maximum authorized speed of 70 mph, where permitted, (factoring in a wind resistance of who knows and who cares??). Where will each train be in exactly the amount of time that it takes Michael Sol to argue a meaningless point with half of people on this board in regards to a subject that only is remotely is close to the original topic???
Answer - The TOFC (trailer/piggyback) train will have arrived at Willow Springs (or, as I called it... Western Springs. Duh). The COFC (stack/container) train might be somewhere in Missouri depending on traffic.
That is the answer to the original question from like three days ago.
I'll save M Sol the trouble of replying to my post and reply for him...
OBJECTION!!!
lawyers...
I'll rate myself with a high degree of wind (read hot air) resistance on this one,
CC
MichaelSol wrote:Fortunately for railroad companies, they don't have to go out and spend millions getting "real world" data, they can see it in the simulation right of the bat.
Fortunately for railroad companies, they don't have to go out and spend millions getting "real world" data, they can see it in the simulation right of the bat.
spbed wrote: Were those Hi HP loocos or low HP locos on that train I paced?
Were those Hi HP loocos or low HP locos on that train I paced?
Doesn't matter, the point was that double stacks on the BNSF have less hp per ton than a pig train would. Did the train run over a scale why you were pacing it so you could figure out the hp/ton? Didn't think so. As I said before BNSF stack trains are allowed 70 MPH and do run at that speed at times, however they are not powered to ensure that they will. Pig trains on the BNSF ARE powered to ensure running at the limit, and to make sure that they get up to the limit quickly. Unless you know what the wieght of the train was that you paced was, the HP of the locos is a moot point.
Bert
An "expensive model collector"
greyhounds wrote: They gave up on streamlining and concentrated on reducing tare weight. That's where the payoff is.
They gave up on streamlining and concentrated on reducing tare weight. That's where the payoff is.
Nobody "gave up" on streamlining. Modern high speed passenger services are extraordinarily engineered around streamlining. Wake up.
For freight service, it just never made much sense, and I doubt anyone has argued that it ever did. The numbers just don't justify any effort in that direction.
A streamlined engine at 100 mph offers 3,035 lbs of resistance compared to its unstreamlined counterpart at 3,995 lbs. [3k hp, 6 axles]. That's just about a 25% improvement, and represents the motion resistance of an entire passenger car. At 120 mph, resistance is 4,048 lbs compared to 5,430, a 34% improvement. At 160 mph, it is nearly 40% difference.
The streamlining reduces the aerodynamic drag alone by 47% at 120 mph.
At 50 mph, only a 20% difference in total motion resistance can be gained from streamlining, just 300 lbs, which is less than .07% (seven hundredths of a percent) of the resistance of the 80 car train at that speed, whereas at 120 mph, the total resistance savings offered by streamlining represents nearly 9% on a 12 car passenger train.
Nobody "gave up" on anything, there are simply appropriate applications and inappropriate applications.
greyhounds wrote: Well, where do I start with this piece of ..... MichaelSol wrote: Reality check for Strawbridge: no one is reducing the weight of the trains you have to drag up the hill. Hasn't happened in 150 years. They keep getting heavier. Strawbridge has completely misstated what has happened. Railroads did not reduce weight, they increased power. A completely different approach. No, you're wrong agiain. They've reduced weight. What do you think aluminum gondolas do? Double stack reduced the tare weight necissary to cary loads by 11% and TOFC spine cars eliminated the solid steel deck found on conventional intermodal flats. They did this to reduce train weight. Now I'll grant you they replaced the reduced tare with payload, but that's OK - since they get paid for moving that stuff. They don't get paid for dragging freight cars around. MichaelSol wrote: .Strawbridge even talks about looking for lower "tare" weights, as though the train and the laws of physics know the difference. The "laws of physics" may not care, but the profit and loss statement does care. Every dime a railroad spends dragging excess tare weight up a hill, and retarding it down a hill is a dime lost. And the dimes add up real quick. MichaelSol wrote: Weights have been increasing and will presumably continue to increase. The talk of reducing weights to increase train performance is a passenger train analogy that has absolutely no relevance to the freight rail industry. Sol's inability to diferintiate between "good weight" and "bad weight" shows his ignorance. "Good weight" is what the railroad is paid to move. "Bad weight" is what the railroad has to put under the "good weight" in order to move it. The goal is to decrease the bad weight and increase the good weight. Sort of like cholesterol. Railroads have continually strived to reduce the "bad weight", by reducing the amount of tare needed to cary a given amount of freight. Sol aparently doesn't understand any of this. MichaelSol wrote: Fortunately for the rail industry, Strawbridge has it wrong, backwards, and upside down. They don't need to lower the weight of cars and the train. They can lower the aerodynamic resistance which is exactly what they have, in fact, been doing when they go up a grade or around a curve. Nope, Sol's wrong again. They gave up on streamlining and concentrated on reducing tare weight. That's where the payoff is.
Well, where do I start with this piece of .....
MichaelSol wrote: Reality check for Strawbridge: no one is reducing the weight of the trains you have to drag up the hill. Hasn't happened in 150 years. They keep getting heavier. Strawbridge has completely misstated what has happened. Railroads did not reduce weight, they increased power. A completely different approach.
Reality check for Strawbridge: no one is reducing the weight of the trains you have to drag up the hill. Hasn't happened in 150 years. They keep getting heavier.
Strawbridge has completely misstated what has happened. Railroads did not reduce weight, they increased power. A completely different approach.
No, you're wrong agiain. They've reduced weight. What do you think aluminum gondolas do? Double stack reduced the tare weight necissary to cary loads by 11% and TOFC spine cars eliminated the solid steel deck found on conventional intermodal flats. They did this to reduce train weight.
Now I'll grant you they replaced the reduced tare with payload, but that's OK - since they get paid for moving that stuff. They don't get paid for dragging freight cars around.
MichaelSol wrote: .Strawbridge even talks about looking for lower "tare" weights, as though the train and the laws of physics know the difference.
.Strawbridge even talks about looking for lower "tare" weights, as though the train and the laws of physics know the difference.
The "laws of physics" may not care, but the profit and loss statement does care. Every dime a railroad spends dragging excess tare weight up a hill, and retarding it down a hill is a dime lost. And the dimes add up real quick.
MichaelSol wrote: Weights have been increasing and will presumably continue to increase. The talk of reducing weights to increase train performance is a passenger train analogy that has absolutely no relevance to the freight rail industry.
Weights have been increasing and will presumably continue to increase.
The talk of reducing weights to increase train performance is a passenger train analogy that has absolutely no relevance to the freight rail industry.
Sol's inability to diferintiate between "good weight" and "bad weight" shows his ignorance.
"Good weight" is what the railroad is paid to move. "Bad weight" is what the railroad has to put under the "good weight" in order to move it. The goal is to decrease the bad weight and increase the good weight. Sort of like cholesterol. Railroads have continually strived to reduce the "bad weight", by reducing the amount of tare needed to cary a given amount of freight. Sol aparently doesn't understand any of this.
MichaelSol wrote: Fortunately for the rail industry, Strawbridge has it wrong, backwards, and upside down. They don't need to lower the weight of cars and the train. They can lower the aerodynamic resistance which is exactly what they have, in fact, been doing when they go up a grade or around a curve.
Fortunately for the rail industry, Strawbridge has it wrong, backwards, and upside down. They don't need to lower the weight of cars and the train. They can lower the aerodynamic resistance which is exactly what they have, in fact, been doing when they go up a grade or around a curve.
Nope, Sol's wrong again.
Typical.
Tare weight changes have not affected axle loadings, which is what the Davis Algorithm (and the laws of physics), have to measure as resistance contributors.
I have re-read this thread in vain for anyone even remotely attempting to argue that improving tare to payload ratios is not a good thing. No where. But that doesn't have a thing to do with the physics of journal, flange and drag resistance.
Why don't we just say it is easier to raise rates?
A completely straw man argument. Or ... perhaps a completely Strawbridge argument.
Good one Strawbridge, you invented your own controversy, came to your own party, and won lone-man bingo contest.
At the end of the day, overcoming aerodynamic drag is the single biggest use of horsepower from a locomotive, or any other motion machine, at higher speeds, and becomes progressively so at progressively higher speeds.
Took five pages to overcome the "resistance" to a well-established, well-understood principle by the usual suspects. No wonder "discussions" on this forum go haywire. Interesting bunch.
Chris30 wrote:Getting something from point A to point B isn't all about top speed or wind drag. It's all about priority. Priority is determined by service levels. Most of your TOFC trains are going to be classified as "Z" trains; high priority intermodal. The BNSF has the ZWSPNBY9/ZNBYWSP9 (Western Springs, IL - North Bay, CA) and the ZWSPRCH9/ZRCHWSP9 (Western Springs - Richmond, CA). The "9" on the end designates that as the highest priority "Z" train and the highest priority train running on the Transcon. Anythin with a "9" on the end is usually going to be a lot of UPS trailers. They pay the big bucks to get their trailers from one spot to another faster than other freight. A stack train might be authorized for the same speed as the "Z" train, 70 mph, but when the stack train is sitting in the hole for twenty minutes waiting for the "Z" to clear the main it isn't doing 70mph (not to mention the reduced speed getting into/out of the siding). CC
Getting something from point A to point B isn't all about top speed or wind drag. It's all about priority. Priority is determined by service levels. Most of your TOFC trains are going to be classified as "Z" trains; high priority intermodal. The BNSF has the ZWSPNBY9/ZNBYWSP9 (Western Springs, IL - North Bay, CA) and the ZWSPRCH9/ZRCHWSP9 (Western Springs - Richmond, CA). The "9" on the end designates that as the highest priority "Z" train and the highest priority train running on the Transcon. Anythin with a "9" on the end is usually going to be a lot of UPS trailers. They pay the big bucks to get their trailers from one spot to another faster than other freight. A stack train might be authorized for the same speed as the "Z" train, 70 mph, but when the stack train is sitting in the hole for twenty minutes waiting for the "Z" to clear the main it isn't doing 70mph (not to mention the reduced speed getting into/out of the siding).
The Acticulation in practice means ....
1. Less Damage to Freight because of Slack Action.
2. Smother Starts and Stops...
3. In Practice....Less side to side action
4. I do remember seing articulated flats on TOFC so they are out there..
------The Lower profile of the TOFC does mean less wind resistance however the debate here seems to be if there shere HULK and BULK and WEIGHT really matter in the game here... On the CSX NYC water level route wind restiance is going to bve greater going west so the game there woul dhave to be figured out.
When DS cars 1st came out they were said to be more fuel efficent then TOFC cars in case you were unaware of that. The hype was that the DS steel wheel resistance to the rails was less then TOFC cars cause they were articulated
MichaelSol wrote: GP40-2 wrote:But, I found the similarities between your statements and the linked web page amusing to say the least. "Similarities?" You mean the single reference in the sixth post on the matter to "2500 hp"? After three posts using completely different information? Yup, I had to go looking on websites to come up with a horsepower number. Couldn't think of one on my own. Pay attention next time. In any case, the numbers used, as I stated at the outset, come from the Davis Equation. Horowitz, to my knowledge, does not have an equation of his own, and if he does, I don't know what it is. Simply nothing really to beg, borrow or steal from Horowitz, it's not his equation. And I did not attribute it to him, I specifically stated that the results were generated by the Davis formula. Regarding the Davis Equation or its related progeny, it is neither my theory nor does it matter if I or anyone else agrees with it or not. But if you don't, what's your substitute? A wild guess? "The first train resistance models by Schmidt and Tuthill (1910-1940's) were developed at UIUC. These findings ultimately led to the Davis Equation for estimating train resistance which is still in use today." Overview of the UIUC Railroad Research Program: A Century of Progress in Railroad Engineering Research at UIUC .
GP40-2 wrote:But, I found the similarities between your statements and the linked web page amusing to say the least.
"Similarities?"
You mean the single reference in the sixth post on the matter to "2500 hp"? After three posts using completely different information?
Yup, I had to go looking on websites to come up with a horsepower number. Couldn't think of one on my own.
Pay attention next time.
In any case, the numbers used, as I stated at the outset, come from the Davis Equation. Horowitz, to my knowledge, does not have an equation of his own, and if he does, I don't know what it is. Simply nothing really to beg, borrow or steal from Horowitz, it's not his equation. And I did not attribute it to him, I specifically stated that the results were generated by the Davis formula. Regarding the Davis Equation or its related progeny, it is neither my theory nor does it matter if I or anyone else agrees with it or not. But if you don't, what's your substitute? A wild guess?
"The first train resistance models by Schmidt and Tuthill (1910-1940's) were developed at UIUC. These findings ultimately led to the Davis Equation for estimating train resistance which is still in use today." Overview of the UIUC Railroad Research Program: A Century of Progress in Railroad Engineering Research at UIUC .
Living nearby to MP 186 of the UPRR Austin TX Sub
MichaelSol wrote: greyhounds wrote: Steamlining does have benifits. But they pale in comparison to reducing the weight you have to drag up a hill. "Steamling" is a passenger train argument, I don't know why it keeps popping up here. It would make an interesting thread of its own, but its just not relevant to freight at freight speeds. Maybe it is, but not much. However, with regard to freight, the poster contends that "steamlining" benefits pale in comparison to reducing the weight you have to drag up the hill. And as Strawbridge cleverly pointed out, that train weight works to the disadvantage of the railroad on a grade. Strawbridge and Diehl talk about reducing weight. Strawbridge even talks about looking for lower "tare" weights, as though the train and the laws of physics know the difference. Pure baloney.
greyhounds wrote: Steamlining does have benifits. But they pale in comparison to reducing the weight you have to drag up a hill.
Steamlining does have benifits. But they pale in comparison to reducing the weight you have to drag up a hill.
"Steamling" is a passenger train argument, I don't know why it keeps popping up here. It would make an interesting thread of its own, but its just not relevant to freight at freight speeds. Maybe it is, but not much.
However, with regard to freight, the poster contends that "steamlining" benefits pale in comparison to reducing the weight you have to drag up the hill.
And as Strawbridge cleverly pointed out, that train weight works to the disadvantage of the railroad on a grade.
Strawbridge and Diehl talk about reducing weight. Strawbridge even talks about looking for lower "tare" weights, as though the train and the laws of physics know the difference.
Pure baloney.
The use of the term "Streamlining," however it is spelled or misspelled in this thread, was my fault for bring in a somewhat related analogy to the original question. I should know better than to confuse the simple minded on this board.
I don't recall any place I talked about reducing the weight of the train, however, as you state Strawbridge (and many others) have, talked about reducing tare weight. This is not so much related to the Operating Department of the railroad (why it would be related to the laws of physics, you'll have to explain) as it is to the Billing Department. If we assume that axle load limits remain the same, any reduction in tare weight will correspond to an equal increase in payload weight for that given car. To paraphrase your statement, the axle load limit doesn't care if it's tare weight or payload weight, but since most shipping charges are based on the weight of the cargo, that car can now haul more payload weight.
user="BuyCSXrailroadStock!"]Greenbrier and Gunderson are making Light Wieght Aluminum Coal Cars.... Must be a reason for this. The fuel savings on a 100 car 10,000 ton freight train? Also I have seen Allunimun Hoppers....So it is only a a matter of time before we have Allnimim Intermodal Flats..
GP40-2 wrote: MichaelSol wrote: Regarding the Davis Equation or its related progeny, it is neither my theory nor does it matter if I or anyone else agrees with it or not. But if you don't, what's your substitute? A wild guess? No need for me to guess at anything when I spend 60+ hours a week on my job using real world empirical data concerning subjects such as this.That's the main difference between people in the industry like myself and foamers like you. You can write all the silly spreadsheets you like, and quote all the theory you want, but the fact is real world data trumps it all.Honestly, have any of you really wondered why nobody who works in the industry takes anything posted on this forum, or any fan forum, seriously?But my-oh-my, it sure is funny watching all you foamers get your panties twisted up over this stuff.
MichaelSol wrote: Regarding the Davis Equation or its related progeny, it is neither my theory nor does it matter if I or anyone else agrees with it or not. But if you don't, what's your substitute? A wild guess?
Regarding the Davis Equation or its related progeny, it is neither my theory nor does it matter if I or anyone else agrees with it or not. But if you don't, what's your substitute? A wild guess?
Good for you. Glad you got it off your chest.
"Steamlining" is a passenger train argument, I don't know why it keeps popping up here. It would make an interesting thread of its own, but its just not relevant to freight at freight speeds. Maybe it is, but not much.
And three things made it possible to handle heavier trains.
1) Increased power.
2) The characteristics of the electric traction motor and electric transmission that permits maximum tractive effort at lower speeds.
3) The use of lower speeds to reduce the aerodynamic resistance.
To paraphrase Secretary Rumsfeld, " you are stuck with the train weight you've got, not the train weight you would like to have."
What happens?
Strawbridge says you have to reduce weight.
You can't. Well you can, but you don't want to if you don't have to.
But, you can change the aerodynamic resistance.
Take Strawbridge's 72,000 lb increased resistance at 50 mph on the 0.5% grade as an example. If the available tractive effort at 50 mph is only 50,000 lbs, there's a problem. Well, you drop to 10 mph. Aerodynamic resistance drops nearly 30,000 lbs. Tractive effort goes up over 100,000 lbs.
Strawbridge wants to reduce weight. That 30,000 lbs of power available from reducing aerodynamic drag is the equivalent of 50 boxcars of that 80 boxcar train, at 50 mph. Which would you do -- drop the weight, or keep the train intact and lower the aerodynamic resistance?
The fortuitous ability to reduce aerodynamic drag is much, much more significant than any feasible means of reducing that much weight. Aerodynamic drag is not only important as a resistance factor at higher speeds, it becomes an important reservoir of available power by lowering speed.
Between TE increases, and aerodynamic drag reductions, a lower maximum speed exists where the train can get up the hill.
The "solution" is not and never has been reducing weight in freight service to achieve operating improvements (we are not talking revenue efficiency of higher cap versus lower cap cars).
And the weight in any case is not going to change on an existing train.
What has happened is that railroads utilize the substantial savings in aerodynamic drag, coupled with increases in tractive effort, at lower speeds, to continue to move ever heavier trains, day in and day out.
This is the interesting conundrum to the posters' insistence that gains can only come from less weight. It hasn't, isn't, and won't be happening. Pure fantasy.
But railroads have, for a long time now, been raising and lowering aerodynamic resistance to overcome flange friction from the weight of trains -- on flat ground, on grades, and on curves.
Every day. Every train.
n012944 wrote: spbed wrote: . Also you did look up in this thread of a BNSF stacker being paced at 70MPH? . Most pig trains on the BNSF are powered with a high hp/ton ratio, to ensure that the train can maintain 70MPH. Stack trains on the other hand, have a lower hp/ton ratio, and while they are authorized to do 70MPH, and will, they will not be able to accelerate to 70 as quickly or maintain it as long. So while I am sure that you did pace a stack train at 70, it has little to do with the first question. Bert
spbed wrote: . Also you did look up in this thread of a BNSF stacker being paced at 70MPH? .
. Also you did look up in this thread of a BNSF stacker being paced at 70MPH? .
Most pig trains on the BNSF are powered with a high hp/ton ratio, to ensure that the train can maintain 70MPH. Stack trains on the other hand, have a lower hp/ton ratio, and while they are authorized to do 70MPH, and will, they will not be able to accelerate to 70 as quickly or maintain it as long. So while I am sure that you did pace a stack train at 70, it has little to do with the first question.
greyhounds wrote: If you don't understand that grades and curvature are significant factors in rail operations and that "Wind Resistance" is an afterthought, you're beyond any possible reason. The most significant resistance factor is the grade. You can either pile on the power or reduce the tare weight to deal with the grades The world isn't flat. The streamliner designers recognized that reducing weight had more benifits than reducing "wind resistance".
If you don't understand that grades and curvature are significant factors in rail operations and that "Wind Resistance" is an afterthought, you're beyond any possible reason.
The most significant resistance factor is the grade. You can either pile on the power or reduce the tare weight to deal with the grades The world isn't flat. The streamliner designers recognized that reducing weight had more benifits than reducing "wind resistance".
Of course all of this explains why cars are getting heavier and trains longer and heavier. Nobody listens to Strawbridge.
No one here has disagreed with the notion that a lighter train is easier to pull. Good grief. Talk about a straw argument. Nobody says that grades do not add resistance. But grades (downhill) also reduce resistance and that's the part of the equation you don't seem to get.
Perhaps that's why variations of the Davis Algorithm often leave that part of the equation off.
Over the entire cycle of a run, back to the starting point, the total effect will be close to zero. Get that, zero.
Of course, the irony of the Strawbridge argument is, the lighter the train, the greater the effect of aerodynamic drag. It goes up. Poor Tom Diehl, he was not only completely unaware that aerodynamic drag would account for 60% of the locomotive power used at 50 mph, if the train were lighter, that percentage would go up!
The point still being, and the point that was originally in contention,
TomDiehl:"As big and heavy as any train is, the wind resistance is a very small factor."
It is not, in fact, "a very small factor" at higher speeds.
I think that notion has been exposed for the fallacy that it was.
Yes, you can invent a whole series of conditions to impose on a train. For some reason you just can't accept the fact that Diehl happened to be dead wrong on the point. As true as your conditions might be under a variety of circumstances, the math still shows that they don't rebut the fact that, at higher speeds, aerodynamic drag is a significant factor.
You can run the train uphill, and you can run the train downhill. You can take it around curves. The problem is, at higher speeds aerodynamic drag remains the most most significant factor as it does for any moving object at the Earth's surface.
And you can postulate a train that only runs uphill, only on curves, and only on Tuesdays, and it doesn't change that fact that for trains in general, aerodynamic drag is a significant factor at higher speeds.
Are you trying to prove it isn't?
You fail. It is.
Are you trying to show there are circumstances under which it might not be true? No one says there aren't, although the math under reasonable circumstances seems to work against your proposal.
But, you have stumbled onto an interesting conundrum ... for another post.
Hugh Jampton wrote:HOLD YER FIRE!!!!!!!!Actually it's kW/metric tonne, but I've converted to hp/ton for youTGVs have a hp/t ratio varying between 24 to 28 depending on the model.Carry on.........
With that kind of horsepower/ton ratio, I would be extremely disappointed if TGV's didn't handle 3-4% grades like they weren't there or fail to accelerate from a stop like a top-fuel dragster. It would be interesting to find out the number of substations required to support that kind of current draw.
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