An email from BMW this morning tells me I can have my i8 in a variety of new colours. Which is nice. But it also tells me:
The BMW i8 is the embodiment of a forward thinking approach...
...All of this technology is wrapped in an elegant shell, modeled [sic] around [sic] the natural aerodynamic marvel of a raindrop...
Now, I hate to be picky and I don't know if they checked this with their own aerodynamics department, but isn't a raindrop spherical, at least when it's moving quickly? It only becomes 'drop shaped' when it's stuck on something. Maybe that's a comment on how we (have to) drive today.
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Does it say what shape they think a rain drop is?
If i think back i think they are aerofoil shaped when falling.
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Something like i remember, not quite but there abouts.
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It will be necessary to translate the NASA graphic into the shape of the PLAN view of the car.
"Flattened on the bottom and with a curved dome top, " translates to 'Flattened on the FRONT and with a curved dome BACK,'
Does this look like i8? Not to me! Only after impact with a flat concrete surface :)
Last edited by: sherlock47 on Sat 21 May 16 at 10:04
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>> Can we trust Nasa on aerodynamics?
They lied about the moon landing.
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>> the natural aerodynamic marvel of a raindrop...
Not sure about the 'marvel' bit - how about (quoting NASA)
the natural aerodynamic top half of a hamburger bun shape of a raindrop...
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"the natural aerodynamic top half of a hamburger bun shape of a raindrop..."
The shape of a hamburger (minus a bite) was inspired to design the hull of the Millennium Falcon, as we all know. (except Old Navy who never saw the film and doesn't get how a hamburger could look like a tramp freighter)
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The implication is that a raindrop has the ideal aerodynamic shape for a car, which seems unlikely.
Last edited by: Manatee on Sat 21 May 16 at 12:59
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>> The implication is that a raindrop has the ideal aerodynamic shape for a car, which
>> seems unlikely.
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It would be the ideal aerodynamic shape for a capsule in free fall, in the open air, accelerating up to terminal velocity.
But a car travels a few inches away from a flat surface, trapping air underneath itself, which has to escape somewhere. I'd have thought that would have a major influence on the airflow, and hence on the ideal shape?
I'd have thought a more realistic comparison in nature might be the shape of a fast bottom-swimming fish - ie very flat?
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>> It would be the ideal aerodynamic shape for a capsule in free fall,
Just as unlikely IMO. A raindrop isn't even the best shape for a raindrop if minimal drag is the objective. I'm quite sure there are shapes that with the same mass and density would have a higher terminal velocity ceteris paribus.
Raindrops are the shape they are because of the effect of surface tension, which per unit mass diminishes as size increases so not all Raindrops are the same shape anyway. I don't think anybody has designed a plane with a fuselage like half a burger bun that goes flat side first.
If you are an aerodynamicist, I retract my theory:)
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>>
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>> Raindrops are the shape they are because of the effect of surface tension, which per
>> unit mass diminishes as size increases so not all Raindrops are the same shape anyway.
>
Good point. There's stuff you can add to water to destroy its surface tension. I wonder what shape rain drops would be if made of it?
Of course there's quite a lot of tension in a car - how fast am I going, can I overtake that car on this bend, that car's newer or more expensive than mine, have I just gone through a speed camera, can I clip 10 minutes off this journey time? Do all BMW owners drive like this or is it just me?
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>>Good point. There's stuff you can add to water to destroy its surface tension. I wonder what shape rain drops would be if made of it?<<
Very simple just add a wetting agent - like w/up liquid.
Turn your i8 into rust more quickly - oh dear will not work - made of " body structure of the BMW i8 is made of carbon fiber-reinforced plastic (CFRP). "
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>> A BMW with sole?
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Certainly. Have you never muttered Ah sole! When you were cut up by one?
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Only if the other driver was booting it at the time, or at least giving it a bit of welly...
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>> >> A BMW with sole?
>> >>
>> Certainly. Have you never muttered Ah sole! When you were cut up by one?
>>
Ultimate thread drift from religon to fish, and to rescue........
some interesting overview here, www.boronextrication.com/2016/03/10/2016-bmw-i8-body-structure/
Last edited by: sherlock47 on Sun 22 May 16 at 10:12
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BMW - Surface tension - sooty123
