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Joined: Dec 2009
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Tricky Dicky
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Tricky Dicky
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It will be a looong time until they are capable of visits down here in the country..


2009 4/4 Sport Henrietta
1999 Indigo Blue +8
2009 4/4 Sport Green prev
1993 Con Green +8 prev





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Just barreling along
Needs to Get Out More!
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Just barreling along
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On the last Amazon construction job I was involved with there will be 300 charge points for vans, oh and a massive private substation plus 24/7 security to stop cables being nicked during install


Jon M
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Originally Posted by Hamwich
Originally Posted by Peter J

As speed increases drag increases with the square of speed


<pedant>
Actually it increases with the cube. And of course the critical thing is CdA, not Cd, so a van with a large frontal area is even worse.

But on the other hand you wouldn't expect to go nearly as fast in a van as you would in a car. A Tesla has a CdA of around .56 compared to a VW Transporter of around 1.3, so as you say, twice the drag, but the impact would be greatly lessened by a reduction in speed. A Tesla at 70mph would need 0.5 x .56 x 30666 = 8586W, a VW at 50 mph would need 0.5 x .1.3 x 11089 = 7207W to overcome air resistance.

So yes, to get equivalent performance would be punitive, but if you accept a lower cruising speed then I can't see it would make that much of a difference, especially in a van with a comparatively low payload.

</pedant>

Interesting post. Where do you get the 30666 and 11089 from? Can you expand on the calculation please.

However, the idea of a lower cruising speed in a white van is completely unacceptable to the yoof who drive them.

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Scruffy Oik
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Scruffy Oik
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Originally Posted by howard

Interesting post. Where do you get the 30666 and 11089 from? Can you expand on the calculation please.


The formula for calculating the energy needed to overcome aerodynamic drag is

0.5 x Air Density x CdA x Speed**3

Air Density can be ignored for comparative purposes, CdA is the drag coefficient multiplied by the frontal area of the vehicle in m**2

All values in SI units, so 50 mph is 22.3m/s which cubes to 11089.567. 70mph is 31.3m/s hence 30666

The result of the formula is expressed in Joules/second, ie Watts. Divide by 746 to get HP of course.

Note that although aerodynamic drag increases with the square of the speed (which is what Peter quite correctly said, and I rather sloppily corrected by not using clear enough terminology), the power expenditure necessary to overcome drag increases with the cube of speed. For a detailed explanation of why this is, see:

https://physics.info/drag/


Tim H.
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Talk Morgan Sage
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Originally Posted by Saxonian
All the Amazon delivery vans that deliver in my neck of the woods are EV's



In MK they have these, that deliver Amazon stuff and Takeaways......

[Linked Image]


"Y mae dafad ddu ym mhob praidd"
1972 4/4, 1981 MGBGT, 1984 FLHT1340, 1980 XLH1000, 1990 ZX10
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I'd love to see a few of those crossing the road......bystanders reactions would be good.
Nick

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Peter J Offline OP
Formerly known as Aldermog
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Traditionalists should sit down....

This is a EV Plus 4 conversion

https://youtu.be/m8HJjUEVpGQ

Made by Electrogenic REV...

they claim 150 miles range and 3X the torque of the original...

www.electrogenic.co.uk if you are tempted.


Peter,
66, 2016 Porsche Boxster S
No longer driving Tarka, the 2014 Plus 8...

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Smile, it confuses them
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Smile, it confuses them
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I suspect this one might need to go behind the spider wall before it gets into a flame war wink


Everyone loves a Morgan. Even me, unless it's broken again.
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S
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Throwing another spanner into the works.........
Local M4 speed limits have been reduced to 50 mph for air pollution improvement.
Will an EV be able to exceed this limit as it is emissions free?
We are entering an era where the “speed kills” mantra is now allied to air cleanliness.
Speed kills by impact in a collision AND by poisoning people with the exhaust.
Remember, there was a recent case that won in a court when a girl with asthma died and her exposure to vehicle exhaust was deemed to trigger a fatal attack.


Plus Four MY23 Furka Rouge
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Peter J Offline OP
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Logically EVs should not be subject to "environmental speed limits" but what has logic got to do with these things?


Peter,
66, 2016 Porsche Boxster S
No longer driving Tarka, the 2014 Plus 8...

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