TomDiehl wrote:How much of the horsepower, by percentage, produced by the locomotive to move the train, is consumed to overcome the wind resistance of the train?
Air resistance, you mean. If you give us the total train tonnage, the total number of cars (and axles) and some idea of what type of car, we can take a shot at it. But we could be off by a factor of two, depending on which version of the so-called "Davis formula" we use.
Oh yes-- tell us the speed too.
TomDiehl: <>If not related to the horsepower required to move the train, why would wind resistance even be a concern?
Getting it yet?
MichaelSol wrote: TomDiehl wrote: MichaelSol wrote: TomDiehl:In this example, known by Kuhler, and by anybody that read his work. He used to lecture on this topic back in the 30's, so that's a long time.I am sure you remember it well. TomDiehl:No, it says that wind resistance of a train at the speeds they travelled was consuming a very small percentage of the power required to move the train, which is EXACTLY what I said. But, that's not what they said, and what you said happens to be wrong, absolutely, unequivocally wrong. You are completely mixed up here, and as usual can't even understand why. They said streamlining had a relatively small effect on the air drag coefficient. That's exactly what the coefficients of air drag friction show. The Davis Algorithm and its refinements are generally accepted by the industry, and any industry that deals with mechanical motion and propulsion. You can ignore them until you are blue, but it doesn't change the fact that 1) you are misrepresenting what Kuhler said, and 2) you are factually wrong. Wrong again Michael. Since you like digging up formulas and figures, how about one that would actually apply to what was being discussed here: How much of the horsepower, by percentage, produced by the locomotive to move the train, is consumed to overcome the wind resistance of the train? Whoa, not so fast, you proposed that air resistance was negligble compared to the effect of the weight of the train. Nothing about horsepower in your proposition. You're trying to change the subject here (I don't blame you, you're dead wrong on your facts on the topic at hand).I am proposing that air resistance is more significant that the motion resistance of weight at a certain point due to the effects of velocity. You are saying length and weight are always most important, that by comparison, air resistance is always negligble, by comparison to weight, presumably at the speeds we are talking about -- presumably in the 40-80 mph range.Why don't you propose to answer, specifically, why "wrong again, Michael"?What would Kuhler say specifically was the effect of motion resistance on a train or a locomotive, and what components relate to weight and what component relates to aerodynamic drag?Where are your numbers to back up your statement besides allusions to speeches given in the 1930s which I am sure you never actually heard but which you now claim in support. Kind of like all the dieselization studies you claimed existed and "relied" on when you actually hadn't seen a single one, isn't it?. Where and how do you show that air resistance is always "negligble" compared weight?A peek at your question however, on a 2500 hp six axle locomotive at 220 tons, at 83% efficiency, the aerodynamic drag begins to exceed the combined weight friction and motion friction at just about 50 mph, and a machine with those characteristics would be unable to exceed 127 mph, at which point 78% of the total motion resistance would be due entirely to the aerodynamic drag on the locomotive.At that point, the total motion resistance would equal the tractive effort available from the locomotive and it would be unable to accelerate past that point assuming it was still on the track.Now, support the answers you claim to have to the proposition you made, and don't try and change the subject. You made the allegation, support it for once with facts and numbers, not misquotes out of magazines.
TomDiehl wrote: MichaelSol wrote: TomDiehl:In this example, known by Kuhler, and by anybody that read his work. He used to lecture on this topic back in the 30's, so that's a long time.I am sure you remember it well. TomDiehl:No, it says that wind resistance of a train at the speeds they travelled was consuming a very small percentage of the power required to move the train, which is EXACTLY what I said. But, that's not what they said, and what you said happens to be wrong, absolutely, unequivocally wrong. You are completely mixed up here, and as usual can't even understand why. They said streamlining had a relatively small effect on the air drag coefficient. That's exactly what the coefficients of air drag friction show. The Davis Algorithm and its refinements are generally accepted by the industry, and any industry that deals with mechanical motion and propulsion. You can ignore them until you are blue, but it doesn't change the fact that 1) you are misrepresenting what Kuhler said, and 2) you are factually wrong. Wrong again Michael. Since you like digging up formulas and figures, how about one that would actually apply to what was being discussed here: How much of the horsepower, by percentage, produced by the locomotive to move the train, is consumed to overcome the wind resistance of the train?
MichaelSol wrote: TomDiehl:In this example, known by Kuhler, and by anybody that read his work. He used to lecture on this topic back in the 30's, so that's a long time.I am sure you remember it well. TomDiehl:No, it says that wind resistance of a train at the speeds they travelled was consuming a very small percentage of the power required to move the train, which is EXACTLY what I said. But, that's not what they said, and what you said happens to be wrong, absolutely, unequivocally wrong. You are completely mixed up here, and as usual can't even understand why. They said streamlining had a relatively small effect on the air drag coefficient. That's exactly what the coefficients of air drag friction show. The Davis Algorithm and its refinements are generally accepted by the industry, and any industry that deals with mechanical motion and propulsion. You can ignore them until you are blue, but it doesn't change the fact that 1) you are misrepresenting what Kuhler said, and 2) you are factually wrong.
TomDiehl:In this example, known by Kuhler, and by anybody that read his work. He used to lecture on this topic back in the 30's, so that's a long time.
TomDiehl:No, it says that wind resistance of a train at the speeds they travelled was consuming a very small percentage of the power required to move the train, which is EXACTLY what I said.
But, that's not what they said, and what you said happens to be wrong, absolutely, unequivocally wrong. You are completely mixed up here, and as usual can't even understand why.
They said streamlining had a relatively small effect on the air drag coefficient. That's exactly what the coefficients of air drag friction show.
The Davis Algorithm and its refinements are generally accepted by the industry, and any industry that deals with mechanical motion and propulsion. You can ignore them until you are blue, but it doesn't change the fact that 1) you are misrepresenting what Kuhler said, and 2) you are factually wrong.
Wrong again Michael.
Since you like digging up formulas and figures, how about one that would actually apply to what was being discussed here: How much of the horsepower, by percentage, produced by the locomotive to move the train, is consumed to overcome the wind resistance of the train?
You're the one trying to change the subject. Chad originally made the statement that one type of train would run slower than the other due to a difference in wind resistance. I replied that the wind resistance wasn't a major factor in the overall power required to run the train, and made reference to major designers in the early streamlining era that stated it was for cosmetic and public relations, rather than functional purposes. Streamlining, in the functional sense, is to reduce wind resistance.
If not related to the horsepower required to move the train, why would wind resistance even be a concern?
TomDiehl: In this example, known by Kuhler, and by anybody that read his work. He used to lecture on this topic back in the 30's, so that's a long time.
TomDiehl: No, it says that wind resistance of a train at the speeds they travelled was consuming a very small percentage of the power required to move the train, which is EXACTLY what I said.
It is easy to put Kuhler's remarks, or anyone else's, into context.
The Davis Equation breaks the forces down into three components. K1 is the resistance or friction resulting from the weight of the machine and the number of axles. For a 250 ton non-streamlined locomotive K1 shows 499 lbs of resistance at 10 mph. It's 499 lbs of resistance at 50 mph, and 499 lbs of resistance at 100 mph, because the frictional resistance due to the weight of the machine does not change with velocity.
K2 is the component that measures the moving friction of the train. Weight is part of this, but so is speed and includes the coefficient of rolling friction empirically measured, which happens to be close to 0.03 for steel wheels on steel rails all of the time. K2 is 75 lbs of resistance at 10 mph, 375 lbs of resistance at 50 mph, and 750 lbs of resistance at 100 mph.
K3 is the component that measures the resistance on the machine (train) due to air drag. In this instance we are only looking at the locomotive itself (since the air drag coefficients are different for different pieces of equipment), but for that 250 ton locomotive, at 10 mph, the resistance due to air drag is only 30 lbs. At 50 mph it is 750 lbs, and at 100 mph it is 3,000 lbs of resistance due to air drag friction. That is 70.6% of the total motion resistance of 4,249 lbs encountered at a speed of 100 mph.
Here's a little proof that CSX engineers could care less whether they've got trailers, double stacks, or autoracks behind them. The timetable says they're cleared for 70mph, and that's what they're run at if clear signals are present. If the trailers' are producing more drag; just kick the engines up a notch! I will say that the uneven trailer spacing produces a great deal more wind when they go by though! (which is good for those hot, gnat-inducing days in FL)
http://www.youtube.com/watch?v=7egWCJh20Iw
anb740
Joe H. (Milepost S256.0; NS Griffin District)
Pictures: http://anb740.rrpicturearchives.net
Youtube: http://www.youtube.com/anb740
Just stating facts & not conjective
chad thomas wrote: spbed wrote: Sorry I do not agree with your theroy. When I was doing it I used a routing of UP-Fre then CNW to Chicago. My company's traffic moved on the UP/CNW hottest train then called the "Falcon" 40 some odd hours LAX/Chic. As that train arrived in Chic in the AM & containers destined for like NY, Balt, Bost, Philly were then DRAYED by the CNW to the eastern RR to connect to trains departing in the PM . From the PNW we used the BNRR & there TT Sea/Chic was 3rd morning delivery in Chic & they also would dray the containers to the eastern RR. I think today those probably are the still the fastest TT out there that I mentioned. Also you did look up in this thread of a BNSF stacker being paced at 70MPH? . greyhounds wrote: BNSF has enough intermodal business so that it is able to facilitate segmentation of the traffic based on customer need. There's no sense in wasting money powering up a train with a high HP/ton ratio and running it Hell Bent for Leather if the customer doesn't want or need such service. More importantly, there's no sense in doing that if the customer won't pay extra for it. 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. On the other hand, a container that's taken a slow boat from China isn't going to get much benifit from a fast ride from LA to Chicago. They get a slower ride at a lower price. I recall the BNSF standard for this level of service as being 400 miles/day. This is their double stack business. It all makes sense, at least on the BNSF. And it's the customer's choice as to what level of service is selected. Other railroads have different markets and different conditions. Yea Ken, Your theory is all wrong. Because Spbecialed said so, so it must be. There is just no such thing as multiple service levels. Just look at his lame video, that will prove it.
spbed wrote: Sorry I do not agree with your theroy. When I was doing it I used a routing of UP-Fre then CNW to Chicago. My company's traffic moved on the UP/CNW hottest train then called the "Falcon" 40 some odd hours LAX/Chic. As that train arrived in Chic in the AM & containers destined for like NY, Balt, Bost, Philly were then DRAYED by the CNW to the eastern RR to connect to trains departing in the PM . From the PNW we used the BNRR & there TT Sea/Chic was 3rd morning delivery in Chic & they also would dray the containers to the eastern RR. I think today those probably are the still the fastest TT out there that I mentioned. Also you did look up in this thread of a BNSF stacker being paced at 70MPH? . greyhounds wrote: BNSF has enough intermodal business so that it is able to facilitate segmentation of the traffic based on customer need. There's no sense in wasting money powering up a train with a high HP/ton ratio and running it Hell Bent for Leather if the customer doesn't want or need such service. More importantly, there's no sense in doing that if the customer won't pay extra for it. 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. On the other hand, a container that's taken a slow boat from China isn't going to get much benifit from a fast ride from LA to Chicago. They get a slower ride at a lower price. I recall the BNSF standard for this level of service as being 400 miles/day. This is their double stack business. It all makes sense, at least on the BNSF. And it's the customer's choice as to what level of service is selected. Other railroads have different markets and different conditions.
Sorry I do not agree with your theroy. When I was doing it I used a routing of UP-Fre then CNW to Chicago. My company's traffic moved on the UP/CNW hottest train then called the "Falcon" 40 some odd hours LAX/Chic. As that train arrived in Chic in the AM & containers destined for like NY, Balt, Bost, Philly were then DRAYED by the CNW to the eastern RR to connect to trains departing in the PM . From the PNW we used the BNRR & there TT Sea/Chic was 3rd morning delivery in Chic & they also would dray the containers to the eastern RR. I think today those probably are the still the fastest TT out there that I mentioned. Also you did look up in this thread of a BNSF stacker being paced at 70MPH? .
greyhounds wrote: BNSF has enough intermodal business so that it is able to facilitate segmentation of the traffic based on customer need. There's no sense in wasting money powering up a train with a high HP/ton ratio and running it Hell Bent for Leather if the customer doesn't want or need such service. More importantly, there's no sense in doing that if the customer won't pay extra for it. 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. On the other hand, a container that's taken a slow boat from China isn't going to get much benifit from a fast ride from LA to Chicago. They get a slower ride at a lower price. I recall the BNSF standard for this level of service as being 400 miles/day. This is their double stack business. It all makes sense, at least on the BNSF. And it's the customer's choice as to what level of service is selected. Other railroads have different markets and different conditions.
BNSF has enough intermodal business so that it is able to facilitate segmentation of the traffic based on customer need.
There's no sense in wasting money powering up a train with a high HP/ton ratio and running it Hell Bent for Leather if the customer doesn't want or need such service. More importantly, there's no sense in doing that if the customer won't pay extra for it.
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.
On the other hand, a container that's taken a slow boat from China isn't going to get much benifit from a fast ride from LA to Chicago. They get a slower ride at a lower price. I recall the BNSF standard for this level of service as being 400 miles/day. This is their double stack business.
It all makes sense, at least on the BNSF. And it's the customer's choice as to what level of service is selected.
Other railroads have different markets and different conditions.
Yea Ken, Your theory is all wrong. Because Spbecialed said so, so it must be. There is just no such thing as multiple service levels. Just look at his lame video, that will prove it.
Living nearby to MP 186 of the UPRR Austin TX Sub
MichaelSol wrote: TomDiehl: No, you're trying to take my original statement by itself rather than an answer to Chad's statement, which is how it was originally posted. Read the first sentence of Chad's original entry above. I offered the Kuhler, Loewy, and Dreyfus statemnt as an example that this has been known for quite some time. Known by who? You? Streamlining had little actual effect on the power needs of trains. That's what Kuhler, et. al. meant and said, because streamlining had little actual effect on overcoming the resistance of trains to air density with increasing speed. It does not say that air density is not important, it simply says that streamlining didn't offer much improvement. Lowering the motion resistance by reducing weight had a bigger effect, because there just wasn't much that could be done about air resistance. Weight, however, could be reduced. That's what Kuhler said and meant. That has nothing, absolutely nothing, to do with what Chad was speaking to. It is, absolutely, not the same thing as saying that air resistance has a "negligble effect" on the power needs of trains attempting to reach higher speeds. As a matter of information, COFC is somewhat higher in the air drag coefficient than a regular boxcar, and TOFC's air drag coefficient more than twice the air drag coefficient of a boxcar. Accordingly, to operate at higher speeds, not only does more power have to be assigned to overcome the air drag coefficient, but more power would be necessary on TOFC to reach the higher speeds than an equivalent boxcar unit even though the loaded boxcar or hopper car was no doubt heavier.
TomDiehl: No, you're trying to take my original statement by itself rather than an answer to Chad's statement, which is how it was originally posted. Read the first sentence of Chad's original entry above. I offered the Kuhler, Loewy, and Dreyfus statemnt as an example that this has been known for quite some time.
TomDiehl:
No, you're trying to take my original statement by itself rather than an answer to Chad's statement, which is how it was originally posted. Read the first sentence of Chad's original entry above. I offered the Kuhler, Loewy, and Dreyfus statemnt as an example that this has been known for quite some time.
Known by who? You?
Streamlining had little actual effect on the power needs of trains. That's what Kuhler, et. al. meant and said, because streamlining had little actual effect on overcoming the resistance of trains to air density with increasing speed. It does not say that air density is not important, it simply says that streamlining didn't offer much improvement.
Lowering the motion resistance by reducing weight had a bigger effect, because there just wasn't much that could be done about air resistance. Weight, however, could be reduced. That's what Kuhler said and meant.
That has nothing, absolutely nothing, to do with what Chad was speaking to. It is, absolutely, not the same thing as saying that air resistance has a "negligble effect" on the power needs of trains attempting to reach higher speeds.
As a matter of information, COFC is somewhat higher in the air drag coefficient than a regular boxcar, and TOFC's air drag coefficient more than twice the air drag coefficient of a boxcar. Accordingly, to operate at higher speeds, not only does more power have to be assigned to overcome the air drag coefficient, but more power would be necessary on TOFC to reach the higher speeds than an equivalent boxcar unit even though the loaded boxcar or hopper car was no doubt heavier.
In this example, known by Kuhler, and by anybody that read his work. He used to lecture on this topic back in the 30's, so that's a long time.
No, it says that wind resistance of a train at the speeds they travelled was consuming a very small percentage of the power required to move the train, which is EXACTLY what I said.
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
MichaelSol wrote: Chad Thomas: 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. TomDiehl: 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. TomDiehl: What I represented and what Kuhler said are exactly the same thing, streamlined styling is more for the looks of the train than performing any function. I tend to believe the statements of someone who worked in the industry during the introduction of streamlining. He obviously considered the laws you state and concluded they were irrelevent in regard to streamlining vs. wind resistance on a train. Weight DOES matter in the realtionship that he stated in the original quote. No. You tried to confuse streamlining with an argument that wind resistance is negligble for power required to move the train, that it was the weight of the train that was significant. You specifically said this: "As big and heavy as any train is, the wind resistance is a very small factor." Kuhler said that streamlining didn't make that much difference in the power needed. What you said was that wind resistance was negligble. It is simply a false statement that wind resistance is neglible because that it not what Kuhler said, he said there wasn't much you could really do about it by streamlining. Read carefully, and you will see the difference.
Chad Thomas: 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.
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.
TomDiehl: 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.
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.
TomDiehl: What I represented and what Kuhler said are exactly the same thing, streamlined styling is more for the looks of the train than performing any function. I tend to believe the statements of someone who worked in the industry during the introduction of streamlining. He obviously considered the laws you state and concluded they were irrelevent in regard to streamlining vs. wind resistance on a train. Weight DOES matter in the realtionship that he stated in the original quote.
What I represented and what Kuhler said are exactly the same thing, streamlined styling is more for the looks of the train than performing any function. I tend to believe the statements of someone who worked in the industry during the introduction of streamlining. He obviously considered the laws you state and concluded they were irrelevent in regard to streamlining vs. wind resistance on a train. Weight DOES matter in the realtionship that he stated in the original quote.
No. You tried to confuse streamlining with an argument that wind resistance is negligble for power required to move the train, that it was the weight of the train that was significant.
You specifically said this: "As big and heavy as any train is, the wind resistance is a very small factor."
Kuhler said that streamlining didn't make that much difference in the power needed. What you said was that wind resistance was negligble. It is simply a false statement that wind resistance is neglible because that it not what Kuhler said, he said there wasn't much you could really do about it by streamlining. Read carefully, and you will see the difference.
youngengineer wrote: As far as wind resistance I can not speak to that. But, on the BNSF speed is dictated by timetable, and indivdual subdivision instructions. All loaded well and platform cars are rated for 70 mph, this being said, weight plays the next determing factor, TOB (tons per operative break) will further reduce train speed usually to 55 mph but possibly even to 45. A piggyback train is generally very light and therefore able to run 70 mph due to the equipment allowing for it, and the fact that TOB is usually under 70. Stack trains especially fully loaded double stack equipment can be very heavy running anywhere from 110 TOB upto 143 TOB, thus the weight becomes the determing factor on speed, generally reducing speed to 55 mph. Probably the worst train for air drag is a empty coal train, although it is permissible or has been in the past to run certain empty coal sets at 60 mph, generally they run at 55 or even 50 mph due to fuel consumption. I think that should help any other questions I would be happy to help
As far as wind resistance I can not speak to that. But, on the BNSF speed is dictated by timetable, and indivdual subdivision instructions. All loaded well and platform cars are rated for 70 mph, this being said, weight plays the next determing factor, TOB (tons per operative break) will further reduce train speed usually to 55 mph but possibly even to 45. A piggyback train is generally very light and therefore able to run 70 mph due to the equipment allowing for it, and the fact that TOB is usually under 70. Stack trains especially fully loaded double stack equipment can be very heavy running anywhere from 110 TOB upto 143 TOB, thus the weight becomes the determing factor on speed, generally reducing speed to 55 mph.
Probably the worst train for air drag is a empty coal train, although it is permissible or has been in the past to run certain empty coal sets at 60 mph, generally they run at 55 or even 50 mph due to fuel consumption.
I think that should help any other questions I would be happy to help
Air resistance, assuming the trains operate on the planet's surface, is a "constant" under all conditions (wind is something else again) in that, while it changes with speed, it changes with speed the same way all the time. Air resistance would not show as a factor. Weight is a variable. Air resistance is not.
youngengineer wrote:Probably the worst train for air drag is a empty coal train, although it is permissible or has been in the past to run certain empty coal sets at 60 mph, generally they run at 55 or even 50 mph due to fuel consumption.
It depens on what setup of engines. I know that conrail VAN trains had GP15-1 thur SD80 MAC engines. Here are some more factors:
how many roadtrailers is train carring?
is it full or empty?
how many engines?
TomeDiehl: 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.
Kuhler said that streamlining didn't make that much difference in the power needed. What you said was that wind resistance was negligble. It is simply a false statement that wind resistance is negligble because that it not what Kuhler said, he said there wasn't much you could really do about it by streamlining. Read carefully, and you will see the difference.
The moving coefficient of a locomotive (internal friction, friction with the rail) is the same whether or not it is streamlined. In the Davis algorithm, the moving coefficient is .03 for either type. The air drag coefficient is .0025 for regular and .0017 for streamlined. Right off the bat, because the decimal place is a full unit to the right, you can see that streamlining offered small improvements compared to the coefficient of friction resulting from a combination of the weight and the number of axles.
That's what Kuhler was saying.
However, moving friction doesn't change with velocity. It's the same, because the weight doesn't change with increases in speed. There is no doubt that lighter weight reduces the friction, but that has nothing to do with speed.
Air resistance losses change with velocity because the air resistance increases by the square of the speed. That adds up fast.
Because of the coefficients above, moving friction is greater than air drag friction at lower speeds, however, because air resistance increases by a square of the speed, at a point, wind resistance becomes a greater factor than the motion friction resulting from the weight of the train.
On an individual locomotive, 250 tons, six axle, this occurs at just over 50 mph. At 100 mph, the air resistance of the locomotive accounts for 71% of the motion resistance of the locomotive, whereas the "weight" as reflected in the moving coefficient of friction, accounts for less than 30% of the motion resistance. That's not "neglible" as you attempted to suggest.
Doesn't matter a twig whether the train is heavy or light, the effect of air resistance is going to increase with speed, and will have an increasingly greater effect on the power needs of the train -- that is contrary to what you attempted to argue. My point is, air resistance is not a negligble force. Anytime the force begins to equal 20, 30, 40% or more it is not "negligble."
Kuhler, incidentally, was a "consultant" -- a category of being you roundly denounced as composed of "losers" a while back. Interesting change of heart.
In this instance, however, what Kuhler was saying was entirely different than what you said, and you cannot change physics by attempting to cover your false argument with the cloak of someone else's reputation.
MichaelSol wrote: TomDiehl wrote: MichaelSol wrote: 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. That isn't what "Lowey" [Loewy] and Dreyfus "recognized", because it's not true.The generally accepted drag coefficients of air are .0017 for streamlined locomotive designs and .0025 for other locomotives designs; that is to say, at any given speed, a true steamline design will encounter approximately 68% of the drag coefficient of air of a non-streamlined design. At 10 mph only 4.5% of the total Resistance to Motion for a streamline design will be accounted for by air drag, vs 6.4% for a non-streamline design.At 50 mph, the percentages are 43% and 53%, respectively. At 80 mph, 60% and 69% respectively. At 100 mph, 68% and 75%, respectively. That is, 75% of the total Resistance to Motion at that 100 mph is accounted for by air drag, alone, on the locomotive. The air drag coefficients are different for freight cars, and for different freight car designs, but in general broadly resemble the locomotive percentages, that is, at higher speeds, the primary drag becomes air drag., and of course is cumulative for the number of such cars in the train. From Streamliner Pioneers, a special issue of Classic Trains, article: The Streamlined Steam of Otto Kuhler (another well known designer of the era): "Streamlining of railroad equipment was for all practical purposes a public-relations endeavor intended to forestall declining ridership. Designers needed not lose sleep over wind resistance, and attempts to reduce it as their aeronautical counterparts. As a means of reducing fuel consumption, lightweight construction was of much greater value than streamlined styling." The difference in resistance between 75% and the 68% permitted by streamlining at 100 mph does not in any way understate the effect of air drag, only that streamlining could only do so much about it. That, and the fact that the steam locomotives referred to operated at the low end of their power curves when starting the train, any train, and weight of the equipment was significant -- more significant than the differential in air drag at the peak of the power curve at, say, 70 mph. What Kuhler said, and what you represented are two entirely different things, and what he said was more relevant to steam, less so to diesel. Newton's First Law summarizes the scenario nicely, that once in motion, the Law is independent of the mass of the body -- weight doesn't matter, because the weight stays the same as speed changes. It takes no more power to pull 10 tons at 10 mph in a vaccuum as it does 10 tons at 100 mph, once it is moving. The difference is, trains don't operate in vacuums -- however they do operate in relatively constant gravity. Resistance forces are what changes the power requirements of a train with increasing speed, but weight isn't one of them, and the First Law describes nicely the effect of air drag on a train -- at higher speeds, it is the single largest component of force acting against the motion of the train and this was true whether the train was powered by steam or diesel.
TomDiehl wrote: MichaelSol wrote: 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. That isn't what "Lowey" [Loewy] and Dreyfus "recognized", because it's not true.The generally accepted drag coefficients of air are .0017 for streamlined locomotive designs and .0025 for other locomotives designs; that is to say, at any given speed, a true steamline design will encounter approximately 68% of the drag coefficient of air of a non-streamlined design. At 10 mph only 4.5% of the total Resistance to Motion for a streamline design will be accounted for by air drag, vs 6.4% for a non-streamline design.At 50 mph, the percentages are 43% and 53%, respectively. At 80 mph, 60% and 69% respectively. At 100 mph, 68% and 75%, respectively. That is, 75% of the total Resistance to Motion at that 100 mph is accounted for by air drag, alone, on the locomotive. The air drag coefficients are different for freight cars, and for different freight car designs, but in general broadly resemble the locomotive percentages, that is, at higher speeds, the primary drag becomes air drag., and of course is cumulative for the number of such cars in the train. From Streamliner Pioneers, a special issue of Classic Trains, article: The Streamlined Steam of Otto Kuhler (another well known designer of the era): "Streamlining of railroad equipment was for all practical purposes a public-relations endeavor intended to forestall declining ridership. Designers needed not lose sleep over wind resistance, and attempts to reduce it as their aeronautical counterparts. As a means of reducing fuel consumption, lightweight construction was of much greater value than streamlined styling."
MichaelSol wrote: 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. That isn't what "Lowey" [Loewy] and Dreyfus "recognized", because it's not true.The generally accepted drag coefficients of air are .0017 for streamlined locomotive designs and .0025 for other locomotives designs; that is to say, at any given speed, a true steamline design will encounter approximately 68% of the drag coefficient of air of a non-streamlined design. At 10 mph only 4.5% of the total Resistance to Motion for a streamline design will be accounted for by air drag, vs 6.4% for a non-streamline design.At 50 mph, the percentages are 43% and 53%, respectively. At 80 mph, 60% and 69% respectively. At 100 mph, 68% and 75%, respectively. That is, 75% of the total Resistance to Motion at that 100 mph is accounted for by air drag, alone, on the locomotive. The air drag coefficients are different for freight cars, and for different freight car designs, but in general broadly resemble the locomotive percentages, that is, at higher speeds, the primary drag becomes air drag., and of course is cumulative for the number of such cars in the train.
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.
From Streamliner Pioneers, a special issue of Classic Trains, article: The Streamlined Steam of Otto Kuhler (another well known designer of the era):
"Streamlining of railroad equipment was for all practical purposes a public-relations endeavor intended to forestall declining ridership. Designers needed not lose sleep over wind resistance, and attempts to reduce it as their aeronautical counterparts. As a means of reducing fuel consumption, lightweight construction was of much greater value than streamlined styling."
The difference in resistance between 75% and the 68% permitted by streamlining at 100 mph does not in any way understate the effect of air drag, only that streamlining could only do so much about it. That, and the fact that the steam locomotives referred to operated at the low end of their power curves when starting the train, any train, and weight of the equipment was significant -- more significant than the differential in air drag at the peak of the power curve at, say, 70 mph.
What Kuhler said, and what you represented are two entirely different things, and what he said was more relevant to steam, less so to diesel. Newton's First Law summarizes the scenario nicely, that once in motion, the Law is independent of the mass of the body -- weight doesn't matter, because the weight stays the same as speed changes. It takes no more power to pull 10 tons at 10 mph in a vaccuum as it does 10 tons at 100 mph, once it is moving. The difference is, trains don't operate in vacuums -- however they do operate in relatively constant gravity.
Resistance forces are what changes the power requirements of a train with increasing speed, but weight isn't one of them, and the First Law describes nicely the effect of air drag on a train -- at higher speeds, it is the single largest component of force acting against the motion of the train and this was true whether the train was powered by steam or diesel.
Actually, I think that wheeled trailers are about as bad as it gets in terms of wind resistance. Not only do you have those trailers acting as sails to gather in air, but you have the air getting sucked under the trailer body and getting tangled up in the "wheelset", to borrow a railroad term.
I'm no expert, but I would guess drag on TOFC would be at least 25% greater.
chad thomas wrote: Mookie wrote: spbed wrote: Is there anyone here from the BNSF that can confirm van trains are run faster then the stacker I paced at 70MPH to confirm your post? Chris30 wrote: The "van trains" are generally faster than "double stack" intermodals because a lot of trailers are for LTL carriers such as UPS and Roadway who pay for the high priority premium expedited service. CC spbed - are they legally permitted to go that fast? Yes, Freights are allowed 70 mph, Passenger gets 90. They use to allow the hotshots 79 if they had less then 70 tons per operative brake but now they are limited to 70. The UP is 75 on the Sunset and 79 for passenger (east of Indio that is).
Mookie wrote: spbed wrote: Is there anyone here from the BNSF that can confirm van trains are run faster then the stacker I paced at 70MPH to confirm your post? Chris30 wrote: The "van trains" are generally faster than "double stack" intermodals because a lot of trailers are for LTL carriers such as UPS and Roadway who pay for the high priority premium expedited service. CC spbed - are they legally permitted to go that fast?
spbed wrote: Is there anyone here from the BNSF that can confirm van trains are run faster then the stacker I paced at 70MPH to confirm your post? Chris30 wrote: The "van trains" are generally faster than "double stack" intermodals because a lot of trailers are for LTL carriers such as UPS and Roadway who pay for the high priority premium expedited service. CC
Is there anyone here from the BNSF that can confirm van trains are run faster then the stacker I paced at 70MPH to confirm your post?
Chris30 wrote: The "van trains" are generally faster than "double stack" intermodals because a lot of trailers are for LTL carriers such as UPS and Roadway who pay for the high priority premium expedited service. CC
The "van trains" are generally faster than "double stack" intermodals because a lot of trailers are for LTL carriers such as UPS and Roadway who pay for the high priority premium expedited service.
Yes, Freights are allowed 70 mph, Passenger gets 90. They use to allow the hotshots 79 if they had less then 70 tons per operative brake but now they are limited to 70. The UP is 75 on the Sunset and 79 for passenger (east of Indio that is).
The Santa Fe Dispatcher's Office in San Bernardino, Calif. during the last half of 1971 issued the following Form 19 "tissue flimsie" train order each day to the westbound (train 99) and eastbound (train 100) Super C:
"Trains nos. 99 and 100 assume passenger train speed not to exceed 79 mph"
At that time Super C was the world's fastest regularly scheduled freight train. It carried trailers and containers (including one or two Flexi-Vans coupled mid-train) on a hot 40-hour schedule between Chicago and Los Angeles. Powered across southern California at 10-hp/trailing ton, this train kept its schedule at speeds approaching greased lightning. In fact, that schedule was so hot that Barstow often wouldn't allow any eastbounds out of the yard from 6am on - not until "Super Charlie" was ready to lead the parade at noontime.
Fourth of July weekend that year a college buddy of mine caught up with no. 99 at Goffs, Calif. (near Needles). We tried to chase the train along U.S. 66 in his suped-up Plymouth Barracuda, but that steel-wheeled rocket just left us in a cloud of dust!
The equipment assigned to this train was nothing special - just ordinary piggyback flats and a pool caboose. The usual locomotive consist was a mixed bag of four FP45s and F45s, but each unit's axle gearing was 59:18 as opposed to the more common 62:15. The higher axle ratio allowed for greater sustained speed.
In the early days of stacks on Conrail, the stack trains were pretty much all APL and/or steamship trains and were dispatched at lower HP/ton with correspondingly slower schedules than the rest of the van fleet. The early stack cars didn't have load/empty braking, either, so were only allowed 50 mph max vs 70 for short van trains and 60 for the longer ones.
Now, domestic stacking has replaced a lot the old trailer traffic and the steamship traffic is getting mixed in with the domestic traffic such that one intermodal train is the same as the next, at least on NS.....
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
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