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Old 11-29-2019, 09:12 AM   #51 (permalink)
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Originally Posted by redpoint5 View Post
Anyhow, I have my own Cybertruck now:
I love the detail on the side glass.

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Old 11-29-2019, 02:20 PM   #52 (permalink)
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Originally Posted by kach22i
Thank you for posting the article, as it shows how much eductaion has yet to be done - starting with Life Style authors like PHIL PATTON.
Self-own in bold.

Journalism is in dire straits compared to aerodynamics. Tim Pool ranted this morning about journalists who spun their narrative off the President's published schedule and then buried the correction in the weeds at the bottom of the story instead of changing the headline.

It's too bad we can't sit around with journalists and spin tales about the turbofan gondolas on the Graf Zeppelin. That would be fun.

Quote:
Originally Posted by RedDevil
Would a boat tail do any good or would it just dangle about in the wake?
The tailgate is larger than the nose (minus chamfers). There's no taper aft the rear axle. It would be huge-mungus.

More likely a bullet boat tail with electric plasma actuators. That could be done in one additonal foot in length.
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Old 11-29-2019, 06:45 PM   #53 (permalink)
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Originally Posted by freebeard View Post
It's too bad we can't sit around with journalists and spin tales about the turbofan gondolas on the Graf Zeppelin. That would be fun.
In defense of the author I think perhaps he took out of context things Wayne Koester was saying, or perhaps Wayne Koester was hinting at current going on's regarding the new Ford Bronco and used the Flex/Fairlane as a historic example as to not upset Ford.

There might even be a possibility that Wayne Koester was remembering an earlier Flex/Fairlane scheme that didn't even make the public's eye at the concept level and was a wind tunnel only scale model.

However all those excuses aside there in an underlying faulty base that the author was working from I suspect. Again some more photos to make the theories at work stick would have prevented the leaps we read through.

EDIT:

http://forums.pelicanparts.com/off-t...ertruck-9.html
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Last edited by kach22i; 11-29-2019 at 07:56 PM..
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Old 11-29-2019, 08:11 PM   #54 (permalink)
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Make of this what you will, I have not verified anything just passing it on.

November 28, 2019
Tesla's Cybertruck Aerodynamics Do Flow Smoothly, as per a CFD Analysis
An aerospace engineer couldn't wait to find out, so he tested the truck's aerodynamics for himself.
https://interestingengineering.com/t...a-cfd-analysis




Quote:
One note to point out is that Martin decided not to share a coefficient of drag number as his assumptions of the wheels and fenders could have affected his results.
Video- Analysis in link.

EDIT:

Fri November 29, 2019
Why Tesla's weird new Cybertruck could be a hit
https://www.cnn.com/2019/11/29/persp...usk/index.html
Quote:
Musk has tweeted that the company received more than 200,000 reservations just days after the unveiling. A remarkable number, even if reservations only require a $100 deposit.
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Last edited by kach22i; 11-29-2019 at 09:40 PM..
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Old 11-29-2019, 10:12 PM   #55 (permalink)
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Even if half the people take their $100 off the table, it's still worth it to overcome the static friction and get it moving. I think they took the idea from Arcimoto.

The situation with the wheels is complex because of the active suspension. I want to see how low it will go. And it would be interesting to compare low-poly models of cars like the 911, etc.
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Old 11-29-2019, 10:42 PM   #56 (permalink)
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Quote:
Originally Posted by kach22i View Post
The author neglects to mention these new sharp front corners are feeding Air-Curtains for the front wheels and the pressure is being redirected. This lack of understanding and attempt to tie it into other things such as minimum radius on the Ford Flex concept (actually called 2005 Ford Fairlane Concept) leads to some distorted assumptions and conclusions in my opinion.
Keep in mind, this article was written in 2009--three years before the first air curtains appeared on a production car.

The most egregious line is the last, in my opinion: "Still, the wind tunnel continues to bring new discoveries. 'Aero,' said Michael Simcoe, a veteran exterior designer at GM, 'remains a black art.'" To contrast, here's an excerpt from W.H. Hucho's keynote paper delivered at the 1976 GM conference on aerodynamic drag:

"As has been shown, most of the knowledge in vehicle aerodynamics is qualitative in nature. Some attempts to transfer results from other fields of aerodynamics to the flow around cars have been quite successful. Nevertheless, what can be deduced from them is guided empiricism rather than systematic design procedures. Unlike other disciplines of fluid dynamics, as for instance turbomachinery or aeronautics, little quantitative information is available on which a rational design procedure for road vehicles can be based.

"What is needed first is a complete picture of the flow field surrounding a car. The various flow modules have to be identified, and their contributions to drag elaborated. The only way to do this is by experiment, and appropriate techniques are available. However, in order to generate complete understanding and to develop design procedures which will convert aerodynamics from an art to a subject of rational engineering, the experiments have to be supported by theory.

"In the course of this Symposium it will be indicated what can be expected from the application of fundamental theoretical flow models, namely: potential flow, boundary layer theory, wake flows and vortex flow-fields. Despite the fact that a complete theoretical model can not be expected in the near future, this theoretical penetration of the subject is not meaningless. Theory must serve to both guide and interpret the experiments. This should bring a better understanding of the flow around cars. This deeper understanding would be of great help in solving the problems related to all four categories of vehicle aerodynamics outlined in Fig. 2 [performance, stability; flow field in detail; engine cooling; heating, ventilating]." (Hucho, W.H. "The Aerodynamic Drag of Cars: Current Understanding, Unresolved Problems, and Future Prospects." In Aerodynamic Drag Mechanisms of Bluff Bodies and Road Vehicles, Sovran, G., Morel, T., and Mason, W., ed., [New York: Plenum Press, 1978], 37)

The publication of books such as Hucho's own Aerodynamics of Road Vehicles in 1987 and the advent of computer simulation have changed ground vehicle aerodynamic engineering, yet designers such as Simcoe still believe it's some sort of magic or intuition. The major problem is still, as is hinted in the article, that these designers get to decide the "look" of a car and then aerodynamic engineers have to make it work without changing that look significantly (as we saw with the Volt, which was still compromised aerodynamically compared to its competitors such as the Prius). It should be the other way around. How much of the Cybertruck's steampunk look was decided on before aerodynamic efficiency was considered, I wonder?
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Old 11-29-2019, 11:02 PM   #57 (permalink)
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How much of the Cybertruck's steamcyberpunk look was decided on before aerodynamic efficiency was considered, I wonder?
The material and fabrication state-of-the-art likely preceded particular design decisions.
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Old 11-30-2019, 12:37 AM   #58 (permalink)
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Quote:
Originally Posted by kach22i View Post
Make of this what you will, I have not verified anything just passing it on.

November 28, 2019
Tesla's Cybertruck Aerodynamics Do Flow Smoothly, as per a CFD Analysis
An aerospace engineer couldn't wait to find out, so he tested the truck's aerodynamics for himself.
https://interestingengineering.com/t...a-cfd-analysis






Video- Analysis in link.

EDIT:

Fri November 29, 2019
Why Tesla's weird new Cybertruck could be a hit
https://www.cnn.com/2019/11/29/persp...usk/index.html
I don't understand (apart from just Tesla fan clubbing) why this article gets so much play and the detailed in depth analysis with detailed specifics and exact results I posted a link to gets zero play. I'm no engineer but am enough of one to know I would be embarrassed to even remotely claim to be an engineer and then scratch together that chicken drawing laking any details and run it through the most basic program and then not even give specifics. If you look at the detailed analysis that was done, the basic limited separation on the roof shown in the chicken scratch model is the same, but put in some details, still leaving out side mirrors any kind of wiper setup, having perfectly flush side glass, etc, and still it spits a .48 Cd. Seems like that is a best case number and people are acting like somehow somebody is getting a .30 on the thing.
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Old 11-30-2019, 10:00 AM   #59 (permalink)
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Perhaps the issue is cognito ergo sum. Or some derivative. We called it the 57 chevy rule way back in college where you "SEE" things that reinforce your beliefs, truth be damned.

I don't think anybody has had the time or compute power to generate hard dimensional data based on the reveal pictures.
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Old 11-30-2019, 12:38 PM   #60 (permalink)
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best case

Quote:
Originally Posted by Hersbird View Post
I don't understand (apart from just Tesla fan clubbing) why this article gets so much play and the detailed in depth analysis with detailed specifics and exact results I posted a link to gets zero play. I'm no engineer but am enough of one to know I would be embarrassed to even remotely claim to be an engineer and then scratch together that chicken drawing laking any details and run it through the most basic program and then not even give specifics. If you look at the detailed analysis that was done, the basic limited separation on the roof shown in the chicken scratch model is the same, but put in some details, still leaving out side mirrors any kind of wiper setup, having perfectly flush side glass, etc, and still it spits a .48 Cd. Seems like that is a best case number and people are acting like somehow somebody is getting a .30 on the thing.
Considering the numbers generated by Spirit at DARKO,and considering the Cybertruck's lack of cooling system,perfect belly pan,mirror delete,and lack of a cab-to-bed gap,as the prototype sits,it has the potential to come in under Cd 0.25.Compared to the Cd 0.36 RAM 1500, with cooling shutters,factory tonneau cover,and active suspension.
We need its frontal area when lowered,and we need it's EPA test weight.From its range we can estimate its power consumption per mile compared to other Teslas.With the weight and a guess at rolling force coefficient,we can guestimate its rolling resistance portion of total load,isolating the aero portion.And from the frontal area,the Cd should fall out of the math.
Pulling a range-extender trailer like BamZipPow's,the combination might crack Cd 0.17.I hope to know more about that next November.

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