Erik_Mag I would assume that the empty hoppers have more air drag than full ones as the load provides some "streamlining effect".
I would assume that the empty hoppers have more air drag than full ones as the load provides some "streamlining effect".
While the evidence suggests you're right, sometimes things like this can be counter-intuitive.
Viewers of "Myth Busters" may recall an episode wherein they found that a pickup with an open bed and the tailgate closed actually had less drag than if the tailgate was left open.
Thus it would not surprise me if someone proved that open hoppers developed a rolling cushion of air similar to a pickup which would actually reduce drag.
Or not.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
tree68Or not.
Not.
You need to look more carefully at why the closed pickup bed produces better aerodynamics. (Including why a gate with holes punched in it, touted as 'more aerodynamic' or more accurately 'less dragging' by the ignorant, is massively less aerodynamic in practice than either a closed or open gate...)
The hopper problem is more than just vortex induction, which is bad enough: the scale is so great that the inside face of the empty car exerts about as much frontal resistance, especially when effectively extended in a quartering wind complicating longitudinal resistance, as the engaging front and side of each car.
My guess is, though, that a train of those center-beam cars with the large plate perforated with oval 'lightening holes' will, car for car, outdrag the hoppers. (And with the lower tare weight, more likely that the naive would assign you more of them to tow...)
OvermodNot.
Oh, I agree - I do understand the "why" behind the pickup phenomenon.
I was mostly pointing out that sometimes things aren't what they would logically seem - ie, the nets for pickups.
It would be interesting to see a wind tunnel test (probably with HO or O models) of the phenomenon.
We've actually had a form of this discussion re: the aerodynamic "nose" for IM cars.
On re-reading, I didn't mean to sound quite so 'sharp' and magisterial. I know you know.
The analysis of drag was done in one of the automobile magazines in the '90s, complete with vortex generation and airflow across the induced vortices, and characteristics of shedding. It is difficult to design a more efficient aerodynamic brake than that sheet with the holes ... unless you make it a flexible net with, say, enough cross-section to be able to retain cargo.
tree68 Erik_Mag I would assume that the empty hoppers have more air drag than full ones as the load provides some "streamlining effect". While the evidence suggests you're right, sometimes things like this can be counter-intuitive. Viewers of "Myth Busters" may recall an episode wherein they found that a pickup with an open bed and the tailgate closed actually had less drag than if the tailgate was left open. Thus it would not surprise me if someone proved that open hoppers developed a rolling cushion of air similar to a pickup which would actually reduce drag. Or not.
Without doing a Mythbusters type experiment - I suspect the 'air ball' that was created in a PU truck's 6 foot bed with a nominal 2 foot tailgate is seriously different than the air flows that are created with a empty hopper where the 'bed' is 40 to 50 feet long with a bed depth of 10 - 11 feet and repeated 100 or more times.
Never too old to have a happy childhood!
tree68Oh, I agree - I do understand the "why" behind the pickup phenomenon.
Put a tonneau cover over the bed, and gas mileage will improve.
Convicted One tree68 Oh, I agree - I do understand the "why" behind the pickup phenomenon. Put a tonneau cover over the bed, and gas mileage will improve.
tree68 Oh, I agree - I do understand the "why" behind the pickup phenomenon.
Put a cap on the bed and the fuel mileage improves more!
BaltACDPut a cap on the bed and the fuel mileage improves more!
How much to compensate for the cost of the cap?
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.
I think the tonneau cover/cap analogy to a "load" versus an "empty" is a better comparison than a tailgate being opened or closed. (assuming an empty bed in all instances)
Convicted One I think the tonneau cover/cap analogy to a "load" versus an "empty" is a better comparison that a tailgate being opened or closed. (assuming an empty bed in all variables)
I think the tonneau cover/cap analogy to a "load" versus an "empty" is a better comparison that a tailgate being opened or closed. (assuming an empty bed in all variables)
The thing with the tailgate is that if the tailgate is closed, a "bubble" forms in the bed which has much the same effect as the tonneau cover, and possibly even a cap. Open the tailgate and that bubble can't form. The phenomenon has been proven.
With a coal hopper, the dynamics are different with regard to the length and depth of the void, hence the feeling that such a bubble would not form in the hoppers.
Made my yearly pilgrimage to Topeka and return with the race car in tow. According to the 'trip computer' on my Dodge Ram - 2450 miles with 14.5 MPG. Best towing mileage I can ever recall in making this trip across I-68 and I-70. Durango was in the 11 - 12 range. Cruise Control set to 75 MPH.
All I know is that with an empty coal train in a stiff wind, speed will pick up by about 5 mph when you go through a location that provides a wind break. Like a forested area or just going through a town. Once back in the open, speed drops back down by about 5 mph.
Jeff
UP is presuming nothing will go wrong and they won't have to stop. But if they do stop another problem can occur: Vandalism to the train. One day while I was working at St Francis a westbound train stopped due to the engr pinching the brakes a bit too much. He should have been able to release his brakes and leave in a few minutes. It took over 3 hours due to repeated incidents of people pulling pins on the train. This train was only about 100 cars. Imagine the problem if the train had three times that many.
wgc53217UP is presuming nothing will go wrong and they won't have to stop. But if they do stop another problem can occur: Vandalism to the train. One day while I was working at St Francis a westbound train stopped due to the engr pinching the brakes a bit too much. He should have been able to release his brakes and leave in a few minutes. It took over 3 hours due to repeated incidents of people pulling pins on the train. This train was only about 100 cars. Imagine the problem if the train had three times that many.
Railroading is based on things not going wrong. Peter developed his principle on the railroad. If you managed to do it one time - Operations Management will dictate that it be done EVERY TIME.
wgc53217One day while I was working at St Francis a westbound train stopped due to the engr pinching the brakes a bit too much. He should have been able to release his brakes and leave in a few minutes. It took over 3 hours due to repeated incidents of people pulling pins on the train. This train was only about 100 cars. Imagine the problem if the train had three times that many.
Convicted OneHow about: Never expect to be able to teach a pig to sing, you'll only waste your time and annoy the pig.
William Claude Dukenfield
BaltACDPeter developed his principle on the railroad.
The Peter principle is this, based on extensive resarch: "In a hierarchy every employee tends to rise to his level of incompetence... in time every post tends to be occupied by an employee who is incompetent to carry out its duties... Work is accomplished by those employees who have not yet reached their level of incompetence."
That statement does not appear to be true. Citation for your source, please? I believe you are that with Murphy's law, which is merely an adage: "Anything that can go wrong will go wrong".
charlie hebdo BaltACD Peter developed his principle on the railroad. The Peter principle is this, based on extensive resarch: "In a hierarchy every employee tends to rise to his level of incompetence... in time every post tends to be occupied by an employee who is incompetent to carry out its duties... Work is accomplished by those employees who have not yet reached their level of incompetence." That statement does not appear to be true. Citation for your source, please? I believe you are that with Murphy's law, which is merely an adage: "Anything that can go wrong will go wrong".
BaltACD Peter developed his principle on the railroad.
Peter and Murphy are first cousins.
charlie hebdoThat statement does not appear to be true.
A railroad is a hierarchy, thus Peter's Principle would follow very nicely. I suspect Balt's statement may have been at least partly tongue-in-cheek, ICYMI.
charlie hebdoI believe you are that with Murphy's law, which is merely an adage: "Anything that can go wrong will go wrong".
Citation for your source, please? Among (many, many!) other things, the original wisdom attributed to Murphy (who was just as real as that great Canadian Laurence Peter) was "if there is any way to do it wrong, he'll find it" which is much more appropriate to the original sense of personal contribution, and ineptitude, than a general observation on the ways things are.
May I suggest that the much darker invocation of Finagle may be appropriate here (commonly expressed as "the perversity of the universe tends to a maximum" -- why the bread always falls buttered-side down). Not only will a given person on the railroad have risen to his or her level of unlearning incompetence, but this will be incompetence specially appropriate to eff things up in that particular position. The general laws of synergy further assure that any combination of incompetences often produces a leveraged result (Lac Megantic being a shining example).
OvermodCitation for your source, please?
A Wiki article was the source. Thank you for your amplification/elucidation.
tree68 charlie hebdo That statement does not appear to be true. A railroad is a hierarchy, thus Peter's Principle would follow very nicely. I suspect Balt's statement may have been at least partly tongue-in-cheek, ICYMI.
charlie hebdo That statement does not appear to be true.
Some might suggest the rails' management is a prime candidate to be the poster child for the Peter principle on megadoses of steroids.
charlie hebdoSome might suggest the rails' management is a prime candidate to be the poster child for the Peter principle on megadoses of steroids.
I'd be tempted to want to take the metaphor the other way, as current rail 'management' appears to be much more typified by absence of competence than by active A-level mismanagement. But there's certainly enough example of PSR-addled management working with a wild will to build a more imperfect railroad recently, some of which definitely fits the extended effect-of-anabolic-steroids comparison!
OvermodNot only will a given person on the railroad have risen to his or her level of unlearning incompetence, but this will be incompetence specially appropriate to eff things up in that particular position. The general laws of synergy further assure that any combination of incompetences often produces a leveraged result (Lac Megantic being a shining example).
However, the Engineer could 'advance' to Travelling Engineer (or whatever they call them these days). The old joke was that those who did not have the numerous skills needed to safely and efficiently run a train, escape to become officers. And unless the TE is actually instructing new Engineers (blind leading the blind), there is a limited amount of damage the TE could do; although if he advances beyond TE, then the potential for really fupping duck will increase.
I think of it as good old fashioned entropy, the tendency for things to deteriorate from order to disorder over time.
Overmod charlie hebdo I believe you are that with Murphy's law, which is merely an adage: "Anything that can go wrong will go wrong". Citation for your source, please? Among (many, many!) other things, the original wisdom attributed to Murphy (who was just as real as that great Canadian Laurence Peter) was "if there is any way to do it wrong, he'll find it" which is much more appropriate to the original sense of personal contribution, and ineptitude, than a general observation on the ways things are.
charlie hebdo I believe you are that with Murphy's law, which is merely an adage: "Anything that can go wrong will go wrong".
Wikipedia offers the explanation that Edward Murphy was a real person, a test engineer working on the Air Force experiments where the then Captain John Stapp subject his own body to extreme g-loads in rocket sled experiments to determine if pilots could survive ejection from supersonic jets. This research also contributed to standards for seat belts and later air bags in automobiles that have saved many people in automobile crashes.
Read https://en.wikipedia.org/wiki/Murphy%27s_law for the full story, but the summary is that Murphy was told to check the instruments for one of these tests, he told the other team members that this check was unnecessary, the team ran the test and the instruments didn't function because they were installed incorrectly by Murphy's assistant, and then Murphy blamed his assistant rather than accepting responsibility for his role in not checking that his assistant did the work correctly.
The Wikipedia article discusses whether we can properly ascribe intent to inanimate objects. It appears that what Murphy's law applies to are humans who can misinterpret instructions or training, in the process get something consistently wrong instead of randomly in error. For example, a technician misunderstands a diagram and wires all the instruments in the same wrong way.
But the buck-passing aspect of the Murphy story has to have some application to the Mega Coal Train and its difficulties.
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
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