[Leader Bee]

Just browsing the internet for cool physicsy stuff i came accross this:



"New "Flying Train" prototype: Apart from aerodynamic drag, trains usually suffer from mechanical resistance in their drive system as well as rolling resistance from the wheels on the track. Researchers at the Kohama Laboratory, Institute of Fluid Science at the Tohoku University in Japan (link) tried to lower overall resistance by adapting another aspect of aerodynamics on its Aero-Train concept. Using the aerodynamic wing-in-ground (WIG) effect, the Aero-Train is able to fly above the track at a height of 10 centimetres (4 in).
The WIG effect occurs when flying very close to the surface. Cruising at its maximum speed of 500 kilometres per hour (310 mph), the aerodynamic lifting force becomes extremely large with a much smaller drag force.
Solar panels are placed on the guide-way's roof, while wind generators are placed alongside in those places where wind energy is generally available. The generated electricity can be fed to the train directly or stored in its on-board batteries. The researchers expect the system to generate much more energy than is consumed by the Aero-Train, thereby making it double as an electric power plant.
The next stage in the development is to build a larger Aero-Train prototype with room for six passengers and a maximum operating speed of 350 kilometres per hour (217 mph). The final, full-scale Aero-Train, with a length of 85 metres (279 ft) and seating capacity for 325 passengers, is aimed to begin service in 2020.


TECHNICAL SPECIFICATIONS:
DRIVE SYSTEM -- Ducted electric fans + WIG-effect
MAXIMUM SPEED -- 500 km/h (310 mph)
LENGTH -- 85 m (279 ft)
WIDTH -- 12 m (40 ft)
WEIGHT -- 70 tons (154,300 lbs)"

The part i've bolded I don't really understand and was hoping it could be explained to me. What i see is that it's somehow a magical perpetual motion device that powers it'self by moving and charging the wind generators; I could perhaps forgive the solar panels part but am I missing something?

[J.C.MacSwell]

Leader Bee, on 5 July 2011 - 02:55 PM, said:

Just browsing the internet for cool physicsy stuff i came accross this:



"New "Flying Train" prototype: Apart from aerodynamic drag, trains usually suffer from mechanical resistance in their drive system as well as rolling resistance from the wheels on the track. Researchers at the Kohama Laboratory, Institute of Fluid Science at the Tohoku University in Japan (link) tried to lower overall resistance by adapting another aspect of aerodynamics on its Aero-Train concept. Using the aerodynamic wing-in-ground (WIG) effect, the Aero-Train is able to fly above the track at a height of 10 centimetres (4 in).
The WIG effect occurs when flying very close to the surface. Cruising at its maximum speed of 500 kilometres per hour (310 mph), the aerodynamic lifting force becomes extremely large with a much smaller drag force.
Solar panels are placed on the guide-way's roof, while wind generators are placed alongside in those places where wind energy is generally available. The generated electricity can be fed to the train directly or stored in its on-board batteries. The researchers expect the system to generate much more energy than is consumed by the Aero-Train, thereby making it double as an electric power plant.
The next stage in the development is to build a larger Aero-Train prototype with room for six passengers and a maximum operating speed of 350 kilometres per hour (217 mph). The final, full-scale Aero-Train, with a length of 85 metres (279 ft) and seating capacity for 325 passengers, is aimed to begin service in 2020.


TECHNICAL SPECIFICATIONS:
DRIVE SYSTEM -- Ducted electric fans + WIG-effect
MAXIMUM SPEED -- 500 km/h (310 mph)
LENGTH -- 85 m (279 ft)
WIDTH -- 12 m (40 ft)
WEIGHT -- 70 tons (154,300 lbs)"

The part i've bolded I don't really understand and was hoping it could be explained to me. What i see is that it's somehow a magical perpetual motion device that powers it'self by moving and charging the wind generators; I could perhaps forgive the solar panels part but am I missing something?

Are the wind generators not placed along the route/track? The advantage would be less transmission losses and of course generating electricity from the wind itself, not the apparent wind produced from the train's movement.

[Leader Bee]

J.C.MacSwell, on 5 July 2011 - 03:02 PM, said:

Are the wind generators not placed along the route/track? The advantage would be less transmission losses and of course generating electricity from the wind itself, not the apparent wind produced from the train's movement.

That would make more sense to me; Though on the test area it doesn't appear there is any roofing. How would the energy be transmitted to the train if there were no conductive surfaces?

[tomgwyther]

It reminds me of the USSR's Ekranoplan, albeit with an electric propulsion as opposed to internal combustion engine.

Here's a short (8min) documentary on the Ekranoplan.

http://youtu.be/Ch2zs-7je_s

[Enthalpy]

Steel wheels produce very little drag, far less than a wing, even with ground effect.
In a train, the biggest drag is from the air flow (and the brakes' cooling!), so the proposed short train would consume much more power per passenger.

The only advantage I see is that at seriously high speed, ground effect accepts a track not as perfect as a rail must be.

Then, the story with Solar panels and wind turbines is decoupled from the train.
They produce expensive electricity, whether on a train track or on a house's roof.
And you could install them at any train track.

[imatfaal]

Enthalpy, on 3 August 2011 - 02:58 AM, said:

Steel wheels produce very little drag, far less than a wing, even with ground effect.
In a train, the biggest drag is from the air flow (and the brakes' cooling!), so the proposed short train would consume much more power per passenger.

You got a citation/backup for those claims. They seem counter-intuitive - and whilst I realise that much that is counter-intuitive is also true - these seem to be pushing that limit.

[J.C.MacSwell]

imatfaal, on 3 August 2011 - 11:26 AM, said:

You got a citation/backup for those claims. They seem counter-intuitive - and whilst I realise that much that is counter-intuitive is also true - these seem to be pushing that limit.

http://www.engineeri...nce-d_1303.html



Rolling Resistance Coefficient

c cl (mm)
0.0002 - 0.001 steel wheels on steel rails
0.0015 - 0.0025 low resistance tubeless tires
0.005 tram rails
0.006 - 0.01 truck tire on asphalt
0.01 - 0.015 ordinary car tires on concrete
0.03 car tires on tar or asphalt
0.04 - 0.08 car tire on solid sand
0.2 - 0.4 car tire on loose sand

A wing that would have a lift to drag of over 50 to 1 would be equivalent to 0.02. You may do better but I doubt you get much better than "truck tire on asphalt" range

[imatfaal]

J C Mac - cool, thanks for that. Makes sense when I read it - I think I was unable to stop considering the huge mass of the train and break it down to a lift/drag weight/friction comparison, where as you point out it becomes clear you would struggle to even reach tires on asphalt.