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Originally Posted by aerohead
Thanks,
1) It may take until you've completed your 3rd year of mechanical engineering studies, when you'e completed fluid mechanics before you understand. $ 75,000 ( US ) ought to get you there.
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In the decades over which I have been writing about cars, I've met many people with undergraduate engineering qualifications who know very little, so it doesn't much surprise me to find another.
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2) If you'll ask your world-class aerodynamicists for assistance, they ought to be able to walk you through Hucho's text, especially the part where fineness ratio is probably the single-most important criteria for the drag coefficient, and has been well established with empirical testing in the real world since 1922.
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Hucho (1987) page 200 for anyone who wants to look. There's just one index reference to fineness ratio in the whole book! And the current - fifth edition - drops 'fineness ratio' entirely from the index. So as I said:
There seems to be a lot of oversimplification happening here - eg "Since drag is directly related to fineness-ratio". No, that's not the case on any real-world car.
If we were striving for shapes with the lowest drag in free air, then I'd imagine fineness ratio would be important. (Say, in the design of airships.)
But we're talking here about cars, so more misleading material from Aerohead.
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3) You can take 25 different homes, of identical size, built on the same street, by 25-different builders, maintained at identical indoor temperatures, year-round, exposed to the same weather, yet yield 25-different energy bills each month. This would be a direct analog for what the L/ square-root of Af offers.
Perspicacity is the game.
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What a great analogy! And so, using your logic, the parallel to fineness ratio would be the house's north-south versus east-west length ratios! That's all we need to do to assess the energy efficiency of these houses - just measure their shape....