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Old 02-24-2021, 01:01 PM   #1 (permalink)
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'Wing'-car talking points

I noodled some figures for the 1993 HONDA Dream-II solar racer, which is an airfoil-derived shape, considering applicability as a future 'production' vehicle.
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* In today's market, the lowest body height, acceptable to 'real' motorists falls in the range of Lamborghini's Huracan, @ 40.49- inches ( 1028.4mm ).
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* The Dream, at 31.276-inches ( 794.4mm ), would have to undergo a body 'inflation' of 129.46% in order to become the 40.49-inch minimum.
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* As all other dimensions would also require the same 'inflation', Dream's overall length would grow to 310.7-inches ( 7891.7mm ).
* Dream's width would swell to 101.88-inches ( 2587.7mm ).
* Dream's overall height would end up at 46.6-inches ( 1183.6mm ) lower, I believe, than any extant production car from any maker.
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I believe that the 'longest' contemporary production vehicle currently for sale may be the RAM 3500, 1-ton, 'Dually', pickup, @ around 249.9-inches ( 6347.4mm ) overall length. I apologize if that's eclipsed by another vehicle.
Losing enough of the knife-edge trailing surfaces to accommodate a rear license plate would reduce Dream's length, at an unknown drag penalty.
Using an 'extensible' tail to provide the 'long-tail' only on the open highway, would allow 'practical length' flexibility.
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Only 'high-cube' 18-wheeler trailer vans attain widths of 102-inches.

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Last edited by aerohead; 02-24-2021 at 01:03 PM.. Reason: add data
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Old 02-24-2021, 01:37 PM   #2 (permalink)
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Here's the part you left out:


http://sunlake.org/solar/archaeology...onda/honda.htm


What I notice is the triangular cross section:


http://www.hondaoldies.de/Korbmacher...ream/dream.htm

Similar to the ME-262. I think it superior to the hemicircular cross-section because it would kill lift driving sideways. Also similar to the Cybertruck/F-117.

Would width necessarily have to scale with the height and length? Does fineness ratio apply laterally?
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Old 02-24-2021, 02:58 PM   #3 (permalink)
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triangular

Quote:
Originally Posted by freebeard View Post
Here's the part you left out:


http://sunlake.org/solar/archaeology...onda/honda.htm


What I notice is the triangular cross section:


http://www.hondaoldies.de/Korbmacher...ream/dream.htm

Similar to the ME-262. I think it superior to the hemicircular cross-section because it would kill lift driving sideways. Also similar to the Cybertruck/F-117.

Would width necessarily have to scale with the height and length? Does fineness ratio apply laterally?
I suspect that there were many tradeoffs between interior packaging, drag, stability, and photovoltaic performance.
While it may have yaw-moment advantage, it might have roll-moment issues. I don't know.
With driver, Dream only weighed 583-pounds. And it had to operate near Australian land trains.
In 'calm' conditions, the car was reported as 'zero downforce' which is same as 'zero-lift', or 'neutral lift.'
Takahiro Iwata did report yaw-induced ' tail-wagging' @ 65-mph. He also said that, ' At 110 km/h. you will become very scared.'
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To maintain all dimensional fidelity, under the rules for verisimilitude ( dynamic similarity ) all dimensions would have to change proportionally, remaining 'identical' with the exception of frontal area.
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Old 02-24-2021, 03:19 PM   #4 (permalink)
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Quote:
Wing'-car talking points
I correct myself, you never promised pix.

I'd like to see that nose rendered in 30x stainless steel.
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Old 02-24-2021, 03:54 PM   #5 (permalink)
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rendered

Probably cost $ millions to pull that off, if at all.
200-ton blanking press.
600-ton transfer press.
Multiple tooling.
Multiple passes to achieve depth of draw without tearing.
Perhaps some heat treating ( annealing ) between strikes.
Today's high strength steel, B-Pillars, must be formed when red-hot.
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Old 02-24-2021, 06:28 PM   #6 (permalink)
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Braked edges and simple curves. No paint required.

The Austin Gigafactory is getting an 8,000-ton press.

Quote:
First Giga Press begins to take shape at Giga Texas ...
https://driveteslacanada.ca/news/tes...-austin-texas/
We also learned during the company's Q4 2020 earnings call an even bigger 8,000-ton Giga Press machine will be required to manufacture parts of the upcoming Cybertruck. The electric truck will also be manufactured in Austin, and deliveries are expected to begin later this year or early 2022.
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Old 02-25-2021, 10:15 AM   #7 (permalink)
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There's explosive hydro forming in a pool of liquid that can exceed those required forces if you have a deep enough swimming pool. Depending on your material, some metals go "plastic" when moved far and fast so they form better, but it probably need a couple of anneals and be triple thickness or more as a blank.
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Old 02-26-2021, 10:30 AM   #8 (permalink)
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no paint

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Originally Posted by freebeard View Post
Braked edges and simple curves. No paint required.

The Austin Gigafactory is getting an 8,000-ton press.
On a dated episode of 'Factory Made,' Hyundai of North America's U.S. factory representative claimed that their paint shop and paint process represented 1/3rd of the total manufacturing cost of the vehicle they produced.
I'll be in Austin on April 6th for a meetup with the AeroStealth's as they come in from a look at Space-X' Boca Chica facility.
We'll be taking a look at the Gigafactory progress the next day.
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Old 02-26-2021, 02:18 PM   #9 (permalink)
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One of my favorite things is watching the daily drone overflights (occasionally) of the Gigafactory at 2x.

You missed when they had two inches of snow over the whole project. They brought in road graders and piled up the snow plus two inches of topsoil, and then loaded it into dump trucks and dumped in one one of the numerous [bayous?] around the site.
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Old 02-26-2021, 10:21 PM   #10 (permalink)
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aerohead: You might be interested in this: Doug McLean | Common Misconceptions in Aerodynamics

youtu.be/QKCK4lJLQHU?t=2822

I sat through 47 minutes of this but he skipped the parts I was waiting for, but he buzzes though the slides in the last minute or so. 'Boundary Layer Separation in 3D' and 'Base drag and Hoerner's jet pump'.

He never gets to the jet pump. searching on the term leads to enginehistory.org/: Waste Heat Utilization in High Output Aircraft Piston Engines by Robert J. Raymond

An interesting article, but it suggests the Hoerner jet pump is synonymous with the Meredith Effect.

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