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Next Gen TGV Duplex


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#21 Devil's Advocate

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Posted 27 August 2018 - 01:30 PM

 

There were only 2 double deckers out of 16 cars, and I was on the upper of one. I don't recall the configuration of the other three levels. The downstairs may have had Green compartments. Wow. It's been 30 years since I did that.

How did those two double deckers not result in an incredible amount of drag? They're taller than the single levels, right?

 

In order for a double decker train to be viable from drag coefficient standpoint it only needs to compare favorably with two single deck trains.


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#22 VentureForth

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Posted 27 August 2018 - 02:03 PM

It's all about the front end. Yes, there is more frontal area. On an airplane, the fuselage has an element of lift by acting sort of as an airflow. This cancels out a little bit of drag. Otherwise, nothing can't overcome drag with plenty of power.

These do the same.

Worth noting that the E1 and E4 both have max speeds of 240 kph, regardless of 12, 10 or 6 cars.

Back to the TGV, I'm fascinated that these have top speeds of 270 and 320 kph. Having power cars vs every car powered lengthens the train, offsetting capacity. But apparently the big difference here is the 6.72 MW vs 9.28 MW power output. In these two cases, though, the E4 Shinkansen carries 817 passengers vs 508 on the TGV.

It's all trades. Power, speed, passenger count, train configuration. Whatever meets the business case.

FWIW, the top speed Sanyo Shinkansen (the extension of the Tokaido) is the N700 at 300 kph. For a single level, 16-car-powered train, it's power output is 17.08 MW! But it also carries 1,323 people. So, 2.6x the capacity of the TGV, with only 1.84x the power.

Edited by VentureForth, 27 August 2018 - 02:03 PM.

14,223 Amtrak Miles. Many more to go.
Completed Routes: Capitol Limited, Palmetto
Also Ridden: Carolinian, Crescent, Pacific Surfliner, Piedmont, Southwest Chief, Silver Meteor, Silver Star, Texas Eagle


#23 cpotisch

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Posted 27 August 2018 - 05:33 PM

 

 

There were only 2 double deckers out of 16 cars, and I was on the upper of one. I don't recall the configuration of the other three levels. The downstairs may have had Green compartments. Wow. It's been 30 years since I did that.

How did those two double deckers not result in an incredible amount of drag? They're taller than the single levels, right?

 

In order for a double decker train to be viable from drag coefficient standpoint it only needs to compare favorably with two single deck trains.

Yes, but a full double decker train is likely going to have be more aerodynamically efficient than a single deck train with a couple bi-level cars, because there's significant drag where the bi-levels extend above the other cars. It's like how the Caltrans Siemens Chargers have a smooth spoiler at the back since they pull bi-levels a couple feet taller than itelf.

 

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Edited by cpotisch, 27 August 2018 - 05:38 PM.

Routes Traveled: Silver Meteor, Silver Star, CrescentLake Shore LimitedCalifornia Zephyr, Sunset Limited, Texas EagleEthan Allen Express, Empire Service, Maple Leaf, AdirondackAcela Express, Northeast RegionalKeystone Service, Downeaster w/ Great Dome
 
Wish List: Auto Train, Cardinal, CONO, Empire Builder, Southwest Chief, Crescent (overnight), Adirondack w/ Great Dome





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