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Old 11-26-2019, 07:19 PM   #31 (permalink)
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Quote:
Originally Posted by freebeard View Post
What you are seeing is a revolution in manufacturability. Folding metal is cheaper than stamping it. No paint is cheaper than paint. Flat glass is cheaper than molded glass.
I'd call this a revolution in re aligning the market's expectations, accepting a vehicle that looks like the shoddiest third world kit car. Those ideas are not new - dozens of flat panel vehicles out there:

https://www.theverge.com/2016/9/11/1...mclaren-africa

My immediate thought was of these Hummer kits made locally a while back:





Paint is cheaper than no paint, but stainless is more expensive than mild steel+paint. I'd say it's more about saving the time involved in painting to ramp up production more quickly, plus no paint issues like they had with the 3. There's talk of vinyl wraps which of course are very expensive and time consuming...

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Old 11-27-2019, 10:55 AM   #32 (permalink)
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nobody

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Originally Posted by redpoint5 View Post
Found out, and then shared the results with nobody. The article doesn't say how good the shape is.

I'm assuming it's pretty decent compared to typical truck design. Could be better with radiused curves instead of sharp ones, but maybe it didn't affect efficiency too severely.
He says that his reason for not sharing the drag coefficient was,that he had a low confidence in accurately modeling of the wheel openings, and how that might impact drag.
My SWAG is sub-0.30.I got Spirit to maybe 0.218 with the boat-tail,and 0.297 without ,but as a BEV (sealed cooling inlet). I'll be very surprised if the Tesla comes in at over 0.3.And we know from the Porsche 914 wind tunnel testing what the influence ground clearance can make.The Cybertruck has an 'ideal' belly and in the 'lowered' position,could come in below most passenger cars.And with aftermarket add-ons,approaching the best concept cars.
It's a coup.And with mods,a coup de grace.
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Old 11-27-2019, 11:02 AM   #33 (permalink)
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30-some %

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Originally Posted by freebeard View Post
By my 4" brass caliper (I had to zoom out three times) the peak is 45% of the length back. I believe the template has it at 30-some %. aerohead?

Modifying to a Ridgeline-style bed eliminates the retractable-in-flight feature. The peak would be a good place for a light bar.

edit: I tried again with a thumbnail on Youtube and got 42%.

2nd edit:
I watched a few more videos. The tonneau is a tambour that stores behind the rear seat, not over it. So the roof peak is an affectation.

It does have a light bar in the peak.
Technically,the frontal area would occur at 1/3rd body length,then utilize the next 2/3rds for decelerative pressure-regain.That would be based upon the full-length body.From there,one could do any degree of truncation and still maintain the 'Kamm-Fachsenfeld' form.
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Old 11-27-2019, 11:16 AM   #34 (permalink)
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ease of manufacturing

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Originally Posted by Piotrsko View Post
The ease of manufacturing is still to be debated. This is Elon we are talking about. Remember the 3 piece wheel tub and that we are talking about making parts of some sort of stainless. Whole different forming and machine processes than cold roll.

A couple of one off's is very different than making 10,000 identical items in a short time.
I've watched some programs on automotive manufacturing,and some of the body stamping operations required three different sets of tooling and separate operations in order to achieve the final degree of draw in the metal before clamping and robotic welding operations could commence.
I'm not a manufacturing engineer,but I suspect that their are inherent cost savings if body shaping operations can be limited to a single operation,even with quick-change dies as Fiat Chrysler uses in RAM pickup truck fabrication.
If hydro-forming is involved,the tooling would be a fraction of conventional tooling cost.Anyone with a subscription to Ward's Automotive will probably already know.
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Old 11-27-2019, 11:21 AM   #35 (permalink)
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See, you were brave enough to take a guess without having done any CFD. The guy isn't worth mentioning if he isn't going to be bold enough to take a stab at it. Afterall, that's exactly what he did for his own curiosity.

If we needed 100% confidence in anything to make a prediction, we'd never get anywhere.
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Old 11-27-2019, 12:18 PM   #36 (permalink)
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curiosity

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Originally Posted by redpoint5 View Post
See, you were brave enough to take a guess without having done any CFD. The guy isn't worth mentioning if he isn't going to be bold enough to take a stab at it. Afterall, that's exactly what he did for his own curiosity.

If we needed 100% confidence in anything to make a prediction, we'd never get anywhere.
I'm asking Santa to arrange for CAR and DRIVER's Don Sherman to put it in the AeroDyn wind tunnel (I think it's too much frontal area for the A2) in Mooresville,North Carolina,in 2021,and publish the Cd,as they already did for the Tesla Model S. Tesla has published Cds for all their vehicles so far,I presume they'll do it for the Cybertruck,once the production design is 'locked in.' The AeroDyn numbers would be a nice backup for the CFD which I presume Tesla will use again.
The NASCAR truck series better hope to ---l Tesla never enters the competition (with a quick-change pack).It's shape,alone,would sweep the field,as the Chrysler Charger Daytona did in the 60s.
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Old 11-27-2019, 12:27 PM   #37 (permalink)
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Quote:
Originally Posted by redpoint5
It amazes me how quickly I've got from an initial impression that the truck is hideous, to it kinda growing on me.
Scott Adams was amazed too. It took him three days before he threw down his $100. I'm trying to convince my son to do that. In two years his Silverado will be paid down and his SRT-8 will have appreciated. I don't think he appreciates needing one less parking space.

oldtamiyaphile — Thanks for mentioning the Ox. There's also the VW Hormiga.

Quote:
Originally Posted by aerohead
Technically,the frontal area would occur at 1/3rd body length,then utilize the next 2/3rds for decelerative pressure-regain....From there,one could do any degree of truncation and still maintain the 'Kamm-Fachsenfeld' form.
Thanks. I found out if you search for 'fashenfeld' you'll never find 'fachsenfeld'. I wanted that for the discussion of Peter Brock's Cobra Daytona Coupe. I think a key feature are the generous chamfers on the front corners.

Here's an article on edges: www.seattletimes.com/.../cutting-edge-aerodynamics-auto-designers-discover-surprising-new-things-about-saving-fuel/
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Old 11-27-2019, 01:12 PM   #38 (permalink)
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Daytona

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Originally Posted by freebeard View Post
Scott Adams was amazed too. It took him three days before he threw down his $100. I'm trying to convince my son to do that. In two years his Silverado will be paid down and his SRT-8 will have appreciated. I don't think he appreciates needing one less parking space.

oldtamiyaphile Thanks for mentioning the Ox. There's also the VW Hormiga.


Thanks. I found out if you search for 'fashenfeld' you'll never find 'fachsenfeld'. I wanted that for the discussion of Peter Brock's Cobra Daytona Coupe. I think a key feature are the generous chamfers on the front corners.

Here's an article on edges: www.seattletimes.com/.../cutting-edge-aerodynamics-auto-designers-discover-surprising-new-things-about-saving-fuel/
My geodesic dome-dwelling neighbor Bob,up the road, is friends with solar car and aircraft designer Larry Mauro,whom visits Bob from time to time.Larry's a many decades-old good friend of Peter Brock and has regaled me with many a fun tale of Brock's exploits,and Peter is held in the highest regard.
The Daytona can almost be considered a follow-on to the coupe that Kamm designed for Briggs Cunningham for LeMans, more than a decade before the Daytona,in which Carol Shelby was probably competing against. Brock,as we see, used Kamm's (Fachsenfeld's) 1930's signature truncation.
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Old 11-27-2019, 03:15 PM   #39 (permalink)
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Interesting:
https://en.wikipedia.org/wiki/Mauro_Solar_Riser

Tell us about that geodesic dome. Diameter/frequency? Wood, metal or concrete?

Over in the VW thread I posted about Peter Brock's low-light bay window. Jay Leno interviews him while they riding around in it. He does have some interesting stories.
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Old 11-27-2019, 04:07 PM   #40 (permalink)
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Interesting:
https://en.wikipedia.org/wiki/Mauro_Solar_Riser

Tell us about that geodesic dome. Diameter/frequency? Wood, metal or concrete?

Over in the VW thread I posted about Peter Brock's low-light bay window. Jay Leno interviews him while they riding around in it. He does have some interesting stories.
It's a 30-someting foot diameter,split-level,sunken living room,with a smaller dome glomed on,concrete foundation,all,over a below-ground concrete,multi-car garage.It has some south-facing passive-solar glazing, looking onto a pool- deck.Bob did a seven-well, ground-sourced heat pump (he retired from an heating and air conditioning career after a couple hitches in the USAF).
The home is all-wood construction,blown-cellulose insulation,composite roof,with bubble skylights.Acreage with shop/hangar,and landing strip,and flies ultralights from the property,hence Larry's shared aviation interest.Bob also has a reputation as a great ultralite 'builder.'

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