From: gl4317@yahoo.com   
      
   In article ,   
    peterwezeman@hotmail.com wrote:   
      
   > On the Talgo trains operated by Amtrak the passenger cars are much lower in   
   > height than the locomotives. The trains have fin-like structures adjacent to   
   > the locomotives to give a gradual change in roof height over a distance of   
   > about a car-length. Is there a measurable reduction on aerodynamic from this   
   > feature or is it more of a styling thing?   
   >   
   >   
   > Peter Wezeman   
   > anti-social Darwinist   
      
      
   I don't know that this would produce any noticeable change in drag, as   
   any comparison to any other equipment Amtrak operates is going to be   
   severely hampered by several facts:   
      
   1. These trains are very light, so it doesn't take that much to move   
   them.   
      
   2. There is a fair amount of drag associated with conventional equipment   
   due to the multiple cars creating multiple aerodynamic drag faces.  In   
   the 1930s they attempted to address this with full-width diaphragms   
   which proved problematic enough that the concept fell into disfavor.   
   The Talgos, however, do the same thing with an articulation joint.   
      
   3. You would have to compare duplicate trips under the exact same   
   circumstances, and that would be hard to do with the variability of   
   trips.  There's a lot of train interference, so different runs drop to   
   lower speeds a lot or stop, then start back up at various locations.   
      
   4. The fins might actually act as a slight barrier to better air flow,   
   as they might set up a second drag face.  However, they may be close   
   enough that it doesn't matter too much.   
      
   Every little bit helps, which is why every year there are more and more   
   truck cabs and trailers with various streamlining added.   
      
      
   > I have seen pictures of Spanish Talgo trains where special locomotives the   
   > same height as the Talgo cars were used. Is there any advantage in stability   
   > on curves or in aerodynamic drag from this? If so, has Amtrak ever considered   
   > getting such locomotives?   
      
      
   The problem is the sheer lack of any economy of scale as it would only   
   be a very few such locomotives operating in the USA.  It would be nice,   
   and the two new Talgo cab cars delivered last year (basically demotored   
   Talgo locomotives with the not so hot looking unique front end) prove   
   that the cab car body could at least be made to meet FRA standards.   
   However, I'm not sure if this could have an engine added to it and have   
   it still be light weight.   
      
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