A 10 year old Trains Magazine I just read had an article anout the wonders of the EMD GP60 and SD60. If I understand it correctly, the first demonstrator units had the classic GEEP style cabs and short hood, but the corners had been smoothed, in order to improve aerodynamics and fuel efficiency.
I don’t know if I’ve ever knowingly seen a GP60 or SD60. Did they retain the rounded corners for better aerodynamics?
Does train aerodynamics have a big effect on locomotive performance? I thought a moving vehicle had to be moving somewhat over 100 m.p.h., before aerodynamics made much difference in performance?
That was only ten years ago? I doubt it, Norris–ten years ago UP was getting its first SD70Ms.
CNW got some SD60s with “Spartan” cabs that were very normal looking–not the rounded-off edges. I don’t think that many EMDs were built with noses and cab fronts with the rounded corners–probably no more than a dozen, tops. You’re right–probably “overdesigning” for a scenario that rarely, if ever, could justify it.
You don’t need speeds in the 100’s for aero to make a difference in transportation…witness the aero mods that have been applied to over the road trucks in the past 30/40 years…the wind deflector’s that have been mounted over the truck cabs, the ‘skirts’ that are being mounted under the trailer floors between the tractor & trailer wheels to minimize the under trailer drag.
With the amount of fuel that is used in transportation, OTR, rail, water…very small improvements can result significant fuel savings for the carriers when replicated across their fleet usage.
Considering the varieties of traffic that railroads handle and the reality that trains are mostly powered for the tonnage they can handle over a territory, rather than the speed that they can handle that tonnage. The reality is most of the aero drag that comes from a train is from the characteristics of the various cars and their combinations within the train, not from the locomotives and how efficiently they go through the air themselves.
Reality check: The article was in the November, 2000 issue of Trains Magazine. It was a special 60th anniversary issue. Every article had a ‘60’ relevence. The first GP60 demonstrators were on the railroads in December, 1984.
I was an aircraft mechanic for the last thirty years of my working life so I think I have a handle on aerodynamics.
Airplanes are designed to have proper airflow around the wings to develop lift and to smooth the flow over the fuselage.
Trains are not designed with consideration of airflow. Depending on the consist they may be dragging many ‘barn doors’ against prevailing winds. Flat cars are not much of a consideration, but cars of height and square ends can surely cause more drag at higher speeds.
As far as aerodynamics are concerned rounded corners on locomotives are of little help. That may not apply to passenger trains where all cars are closely coupled.
BatACD mentioned the aerodynamic of the trucking industry and how they have advanced aiding particularly, fuel consumption… Kind of like **Norm48327’**s knowledge of aircraft and the involvement of aerodynamics of airplanes.### I was involvd with trucks, and in and out of the trucking industry for about thirty years.### In 1985 the Kenworth Truck Co, introduced the fist truck that specifically advertised added fuel mileage in a ‘somewhat’ aerodynamically designed cab the 1985 T600 called " Ant Eater’ as a term endearment or derision; depending on one’s involvement ( owner or driver or by-stander). Prior to that as BaltACD mentioned aerodynamics were pretty much generally confined to any number of cab mounted fairings or fairings systems.### Kenworth and Pete and International and some of the other manufacturers utilized big wide fronts to house larger horsepower engines in their trucks. Big wide nosed Marmon’s, and Autocar’s were noted for huge, wide-nosed chrome radiators and the fronts that housed them.### There were limited experiments with inflatables (as on the rear of the trailer- a sort of a boat tail effect), and all manner of fairings between the cab, and trailer; as well as under trailer mounted fairing systems).### Strick Trailer Co even fielded an experiment utilizing a cab-under trailer for use on doubles. More for length, but applicable to aerodynamics also.### American railroads have seemed to get away from any interest in aerodynamics. ASince the advent and later demise of long distance passenger equipment that was "Streamlined"and the locomotives designed to pull them; all seemed more designed for the sleek look provided.
I’m not sure if this addresses your question, but I remember running empty 112-car coal trains that would not get much above 35mph with only one SD40-2 locomotive, even though the train weighed only 3500 tons. All the empty hoppers acted like parachutes. I would guess the same (but to a smaller degree) would apply to a train of empty bulkhead flats. I would also guess that aerodynamics would be much more of a factor on IM trains rather than on a manifest.
Rounded hood corners weren’t for aerodynamics, but surely helped to make a lot of railfans love the Alco RSI-2-3’s. Along with their cleaner looking trucks, smokier exhausts, and burbling/galloping/comforting sound at rest, they were more friendly or even cuddlier to be with. Baldwin did a litle of the same thing on it’ AS’s,
FM trainmasters were ugly here on the Reading.
As a child, the only EMD geep I liked was the American Flyer one with the wire couplers. It could pull the whole yard or the paper off the walls.
Wow, cuddly for a locomotive, and now there’s Thomas and friends.
I wonder what the “accelerometer” function in a modern locomotive’s speedometer would show with such a train when hit by a sudden gust of wind. In theory, it would register a slowdown of maybe a couple tenths of an MPH . . . That might be a good way to get a handle on the’ real-life’ significance of aerodynamics to freight trains.
This touches on a question that has always been in the back of my mind regarding Superliner equipment. Recalling that, after some early experimantation with lower slung and articulated, streamlined passenger equipment (M-10000, Pioneer Zephyr, Land O’ Corn, etc.) higher speeds of the 30’s and 40’s were frequently attained with non-steamlined equipment in consists or (as in the case of the early 400’s) none at all.
So, aside from the design of the locomotive such as on French, Chinese and other HSR trainsets is there any particular aerodynamic problem with operating Superliners at HSR (180-200mph+) speeds? Or would it pay to redesign from the rail up?
Wind resistance increases with the square of the velocity, so when trains get quick aerodynamics start to matter, and really matter over 100mph. I’m afraid I don’t know the formal symbols, but doing the maths is salutory. Imagine a train with a resistance of 2. Travelling at 50mph resistance is 2x50squared ie 5,000. At 100mph is 2x100squared ie 20,000. Double speed, quadruple resistance. At 125mph it’s 2x125squared - 31,250. Add a quarter to the speed and resistance goes up by over half. At 200mph it’s 2x200 squared - 80,000. So comparing 50mph with 200mph speed has quadrupled, wind resistance has increased sixteeen times.
Clearly one can shove vast amounts of horsepower at something and speed will increase, but at diminishing returns if aerodynamics aren’t re-worked. Also while it’s less important with trains than cars much of high speed car aerodynamics (eg Formula 1) is designed to keep the car down, ie on the road so the wheels can transmit energy from engine to road.
One further point is that all aerodynamics need to be catered for - pressure sealing vehicles so that they can pass in tunnnels without truly horrible pressure waves. 125mph (ie 250mph closing speed) is about as quick as unsealed trains can pass in a tunnel, and even then passengers will notice their ears popping. Some of the German high speed lines have especially wide tunnel mouths to try allow air to escape as a train enters them.
All aerodymics also means the bottom of the train - really high speeds can generate forces big enough to move ballast, and stones hitting metal at 200mph is not welcomed. Caused a problem with German high speed trains on French high-speed lines. The latter are ballasted, the German high speed lines have concrete track formations with no ballast.
My conclusion is that even if you could put enough grunt in front of a superliner (which would need an electric engine) redesign would be needed.
Also recall that the power required to generate a given tractive effort scales with speed, so quadrupling speed will increase the amount of power to overcome aero drag by a factor of 64. IIRC, aero drag is just starting to become significant with American passenger equipment at around 50 MPH.
FWIW, the earliest UP streamliners had smooth bottoms, but the increase in maintenance costs outweighed fuel savings. These were not particularly high speed trains.
Wind resistance increases with the square of the velocity, so when trains get quick aerodynamics start to matter, and really matter over 100mph. I’m afraid I don’t know the formal symbols, but doing the maths is salutory. Imagine a train with a resistance of 2. Travelling at 50mph resistance is 2x50squared ie 5,000. At 100mph is 2x100squared ie 20,000. Double speed, quadruple resistance. At 125mph it’s 2x125squared - 31,250. Add a quarter to the speed and resistance goes up by over half. At 200mph it’s 2x200 squared - 80,000. So comparing 50mph with 200mph speed has quadrupled, wind resistance has increased sixteeen times.
Clearly one can shove vast amounts of horsepower at something and speed will increase, but at diminishing returns if aerodynamics aren’t re-worked. Also while it’s less important with trains than cars much of high speed car aerodynamics (eg Formula 1) is designed to keep the car down, ie on the road so the wheels can transmit energy from engine to road.
One further point is that all aerodynamics need to be catered for - pressure sealing vehicles so that they can pass in tunnnels without truly horrible pressure waves. 125mph (ie 250mph closing speed) is about as quick as unsealed trains can pass in a tunnel, and even then passengers will notice their ears popping. Some of the German high speed lines have especially wide tunnel mouths to try allow air to escape as a train enters them.
All aerodynamics also means the bottom of the train - really high speeds can generate forces big enough to move ballast, and stones hitting metal at 200mph is not welcomed. Caused a problem with German high speed trains on French high-speed lines. The latter are ballasted, the German high speed lines have concrete track formations with no ballast.
My conclusion is that even if you could put enough grunt in front of a superliner (which would need an electric engine) redesign would be needed.
I don’t believe that is true. HSR’s in Germany (ICE’s) largely run on right of way that has concrete sleepers on well-maintained stone ballast. Same for French TGVs and Japanese Bullet trains: all run on ballast bound tracks. Their way of avoiding the problem of stones being sucked up is having the underside of coaches enclosed and smooth and reducing the number of smaller loose stones in the track bed. Concrete slab track beds are used on some stretches in Germany and quite heavily used in China.
The German Neubaustrecke with 300 kph top speeds are all slab track. Older Neubaustrecke and all Ausbaustrecke with 250 kph top speeds use concrete ties with ballast. The slab track has ballast shoulders, but the slab rests directly on the sub-grade, the shoulders are ballasted to control sideways movement and for drainage. Remember the HSR trainsets have fairly low axle loadings, and are relatively light in total weight.
