[FoRK] LA Traffic - solution?

Stephen D. Williams sdw at lig.net
Fri Aug 31 22:49:53 PDT 2012


Electric Ducted Fans (EDF) are also known as electric jets.
The "jet" in jet engine is more about "rearward exhaust of a jet of flued or heated air and gasses". If you removed "heated", which 
is more a how than what, it fits OK.

http://dictionary.reference.com/browse/jet+engine

Other definitions make the connection of a gas turbine being a jet engine. I think that is an example of temporary assumptions of an 
era that one thing means another. That seldom holds forever (phone, mail, lamp, etc.).

But also, a jet plane has a certain set of characteristics of size, carrying capacity, speed, efficiency, etc. That one element of 
it uses a gas turbine isn't central or necessary to the overall definition. I invoke duck typing on any derivative of a jet plane 
that is substantially similar.

All-electric passenger aircraft in the jet aircraft categories have been explored and analyzed, in 2007-2009 apparently.
http://www.drives.co.uk/fullstory.asp?id=2033
Technology news: July 2007

Superconducting motors could propel all-electric aircraft

Researchers in the US are predicting that superconducting motors could be used to propel a new generation of all-electric passenger 
aircraft which, they say, will be quieter, more efficient, less polluting, more controllable, and cheaper and easier to maintain 
than today’s jet aircraft. The researchers, funded by NASA and the US Department of Defense, suggest that future aircraft could be 
fuelled using liquid hydrogen which could also be used to cool the propulsion motors down to the cryogenic temperatures needed to 
achieve superconductivity.

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=5153109&isnumber=5166701&punumber=77&k2dockey=5153109@ieeejrns&query=%28%28masson%29%3Cin%3Eau+%29&pos=5&access=no
http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=5067019&isnumber=5166701&punumber=77&k2dockey=5067019@ieeejrns&query=%28%28masson%29%3Cin%3Eau+%29&pos=6&access=no

sdw

On 8/31/12 7:14 PM, John Parsons wrote:
>
>
>
> ________________________________
>   From: Stephen Williams <sdw at lig.net>
> Sent: Friday, August 31, 2012 9:41:17 AM
> Subject: Re: [FoRK] LA Traffic - solution?
>   
>> "Although only barely possible for even 2 seaters, the possibility of electric jets..."
> Contradiction in terms. For an engine or other device to produce a true "jet" for propulsion, some chemical or combustive process is required. If you are alluding to ducted fans driven by electric motors, they cannot be construed as true "jets". While this tech is used in RC modelling, the tech is a long way from prime time.
>
> For electrically powered ducted fans to be prime movers, we would need to replace the heavy iron and copper in traditional electric motors with lightweight and electro-magnetically conductive materials, to say nothing of the weight of the on-board storage (presently batteries, but possibly super-capacitors in the future). AFAIK the most efficient possibilites for electric airplanes continues to be propeller driven tech.
>
> Still, I've been out of that particular field for some time now, and while the physics hasn't changed, inventiveness continues. Am I seriously out-of-date or was this a typo?
>
> JP



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