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High speed passenger trains such as the French TGV reduce drag by
having the back end of the train configured as what the aerodynamics
people call an "afterbody", bringing the air together smoothly
behind the train without creating a low pressure wake. Such
afterbodies are also coming into use on highway semi-trucks.
I have wondered if such a thing could be of possible benefit to
freight trains as well, or if a freight train is dragging so
much air with it in its boundary layer that an afterbody would make
no difference. I am interested in hearing from anyone who
has had occasion to watch a train of box cars or hopper cars
pass by in conditions of drifting snow. Was the snow settling
on the top of the cars or was there enough relative wind to
sweep the snow off? Was a low-pressure "bubble" visible
behind the train, as I have seen behind highway trucks
in snow?
Thank you for any replies,
Peter Wezeman
anti-social Darwinist
At Wed, 12 Dec 2018 16:35:55 -0800 (PST) peterwezeman@hotmail.com wrote:
High speed passenger trains such as the French TGV reduce drag by
having the back end of the train configured as what the aerodynamics
people call an "afterbody", bringing the air together smoothly
behind the train without creating a low pressure wake. Such
afterbodies are also coming into use on highway semi-trucks.
I have wondered if such a thing could be of possible benefit to
freight trains as well, or if a freight train is dragging so
much air with it in its boundary layer that an afterbody would make
no difference. I am interested in hearing from anyone who
has had occasion to watch a train of box cars or hopper cars
pass by in conditions of drifting snow. Was the snow settling
on the top of the cars or was there enough relative wind to
sweep the snow off? Was a low-pressure "bubble" visible
behind the train, as I have seen behind highway trucks
in snow?
The aerodynamics become more of an issue at higher speeds. I expect the >freight trains do no travel fast enough to have enough gain from aerodynamics.
The TGV and other super high speed trains have much more to gain at the higher
speeds and more importantly, and high acceleration rates (leaving stations and
getting back up to speed quickly is an important consideration).
Thank you for any replies,
Peter Wezeman
anti-social Darwinist
On Wed, 12 Dec 2018 20:40:05 -0600, Robert Heller
<heller@deepsoft.com> wrote:
At Wed, 12 Dec 2018 16:35:55 -0800 (PST) peterwezeman@hotmail.com wrote:
High speed passenger trains such as the French TGV reduce drag by
having the back end of the train configured as what the aerodynamics
people call an "afterbody", bringing the air together smoothly
behind the train without creating a low pressure wake. Such
afterbodies are also coming into use on highway semi-trucks.
I have wondered if such a thing could be of possible benefit to
freight trains as well, or if a freight train is dragging so
much air with it in its boundary layer that an afterbody would make
no difference. I am interested in hearing from anyone who
has had occasion to watch a train of box cars or hopper cars
pass by in conditions of drifting snow. Was the snow settling
on the top of the cars or was there enough relative wind to
sweep the snow off? Was a low-pressure "bubble" visible
behind the train, as I have seen behind highway trucks
in snow?
The aerodynamics become more of an issue at higher speeds. I expect the >freight trains do no travel fast enough to have enough gain from aerodynamics.
The TGV and other super high speed trains have much more to gain at the higher
speeds and more importantly, and high acceleration rates (leaving stations and
getting back up to speed quickly is an important consideration).
Thank you for any replies,
Peter Wezeman
anti-social Darwinist
I thought UP had some air smoothed containers to put at the front of a
train, immediately behind the engine, for aerodynamic purposes. Then
there's the attachments you see on the back of some trucks which look
to me like they would suck air in to the rear but since I don't
believe truckers would worsen their gas mileage deliberately must have
some kind of benefit.
At Thu, 13 Dec 2018 09:51:28 +0000 Graham Harrison <edward.harrisom.one@btinternet.com> wrote:
Another point to consider is a train has one front end and one rear end for potentially hundreds of intermediate cars, so the benefits per car of streamlining the front and rear are small compared with a (road) truck that has one front and one rear per trailer (occasionally two). For railways, an important consideration is streamlining of the underframe and achieving as smooth a transition, with a small a gap as possible, between adjacent cars. High speed passenger trains put a lot of design effort into these factors, most freight trains conspicuously don't.On Wed, 12 Dec 2018 20:40:05 -0600, Robert Heller
<heller@deepsoft.com> wrote:
At Wed, 12 Dec 2018 16:35:55 -0800 (PST) peterwezeman@hotmail.com wrote:
High speed passenger trains such as the French TGV reduce drag by
having the back end of the train configured as what the aerodynamics
people call an "afterbody", bringing the air together smoothly
behind the train without creating a low pressure wake. Such
afterbodies are also coming into use on highway semi-trucks.
I have wondered if such a thing could be of possible benefit to
freight trains as well, or if a freight train is dragging so
much air with it in its boundary layer that an afterbody would make
no difference. I am interested in hearing from anyone who
has had occasion to watch a train of box cars or hopper cars
pass by in conditions of drifting snow. Was the snow settling
on the top of the cars or was there enough relative wind to
sweep the snow off? Was a low-pressure "bubble" visible
behind the train, as I have seen behind highway trucks
in snow?
The aerodynamics become more of an issue at higher speeds. I expect the >freight trains do no travel fast enough to have enough gain from aerodynamics.
The TGV and other super high speed trains have much more to gain at the higher
speeds and more importantly, and high acceleration rates (leaving stations and
getting back up to speed quickly is an important consideration).
Thank you for any replies,
Peter Wezeman
anti-social Darwinist
I thought UP had some air smoothed containers to put at the front of a train, immediately behind the engine, for aerodynamic purposes. Then there's the attachments you see on the back of some trucks which look
to me like they would suck air in to the rear but since I don't
believe truckers would worsen their gas mileage deliberately must have
some kind of benefit.
I'm not saying that adding aerodynamic features would not help freight trains,
just that I expect that cost / benefit analysis might not be good enough to warrant extraordinary measures for typical mixed freight, which might not travel at high enough speeds to matter or that there are too many complications (eg a wide variaty of freight car shapes). For some kinds of unit trains, partitularly hot-shot container trains, it might make some sense.
Super high speed *passenger* trains have uniform car shapes, run at high speeds with the need for fast acceleration, so aerodynamic features become critial. Truckers have a narrower margin, so it makes sense to squeze every penny's worth of advantage they can get, and again, rapid acceleration is also
a consideration as well.
I have wondered if such a thing could be of possible benefit to
freight trains as well,
At Thu, 13 Dec 2018 09:51:28 +0000 Graham Harrison <edward.harrisom.one@btinternet.com> wrote:
On Wed, 12 Dec 2018 20:40:05 -0600, Robert Heller
<heller@deepsoft.com> wrote:
At Wed, 12 Dec 2018 16:35:55 -0800 (PST) peterwezeman@hotmail.com wrote:
High speed passenger trains such as the French TGV reduce drag by
having the back end of the train configured as what the aerodynamics
people call an "afterbody", bringing the air together smoothly
behind the train without creating a low pressure wake. Such
afterbodies are also coming into use on highway semi-trucks.
I have wondered if such a thing could be of possible benefit to
freight trains as well, or if a freight train is dragging so
much air with it in its boundary layer that an afterbody would make
no difference. I am interested in hearing from anyone who
has had occasion to watch a train of box cars or hopper cars
pass by in conditions of drifting snow. Was the snow settling
on the top of the cars or was there enough relative wind to
sweep the snow off? Was a low-pressure "bubble" visible
behind the train, as I have seen behind highway trucks
in snow?
The aerodynamics become more of an issue at higher speeds. I expect the >freight trains do no travel fast enough to have enough gain from aerodynamics.
The TGV and other super high speed trains have much more to gain at the higher
speeds and more importantly, and high acceleration rates (leaving stations and
getting back up to speed quickly is an important consideration).
Thank you for any replies,
Peter Wezeman
anti-social Darwinist
I thought UP had some air smoothed containers to put at the front of a train, immediately behind the engine, for aerodynamic purposes. Then there's the attachments you see on the back of some trucks which look
to me like they would suck air in to the rear but since I don't
believe truckers would worsen their gas mileage deliberately must have
some kind of benefit.
I'm not saying that adding aerodynamic features would not help freight trains,
just that I expect that cost / benefit analysis might not be good enough to warrant extraordinary measures for typical mixed freight, which might not travel at high enough speeds to matter or that there are too many complications (eg a wide variaty of freight car shapes). For some kinds of unit trains, partitularly hot-shot container trains, it might make some sense.
Super high speed *passenger* trains have uniform car shapes, run at high speeds with the need for fast acceleration, so aerodynamic features become critial. Truckers have a narrower margin, so it makes sense to squeze every penny's worth of advantage they can get, and again, rapid acceleration is also
a consideration as well.
snip
None the less, I always liked the 1950s look of a bulldog
streamlined locomotive hauling an unbroken line of streamlined
coaches. When Amtrak came along with Amfleet and hi-levels
it distorted the look.
Actually, I don't know how the shape of Metroliner/Amfleet came
about. They were based on the Metroliner MU design. Was
the tubular shape for wind resistance or just to look cool?