Reeler
Decade of Pure EV Driving
There is a reason that Tesla didn't give this number in the reveal. Past reveals bragged about the amazing Cd.
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There is a reason that Tesla didn't give this number in the reveal. Past reveals bragged about the amazing Cd.
Apples and oranges. Keep in mind, Cd is a coefficient we use to compare and not the actual load.
In airfoils, we’re mostly worried about lift, and as a result that drag coefficient is set up to match that lift coefficient - to get the drag force from it you multiply by the wing planform area (and other factors.)
The drag coefficient for cars is usually defined using the flat plat cross section area I believe.
As a result, they aren’t comparable and the airfoil Cd should be one fifth to one tenth the car Cd for bodies of identical shape/drag.
No one expects it to match the cars, but for a truck it will be very good. Also they already packed a lot of information into the presentation, too much info tends to be counterproductive. No doubt they will do some followups closer to the release date.
I actually think the Cd might be as good as the cars or even a little better.
Longer shapes usually have less drag, and that long rear deck lets you dump half the cross section in a very smooth even way. The air dam up front appears to be pretty effective in blanking the front wheel wells from the CFD folks have been tossing around, and there aren’t any mirrors or other awkward protrusions except the rear wheel wells.
Of course, I’m talking about Cd here. There’s no avoiding the fact that it’s got a bunch of cross sectional area - substantially more than even an X, so the total drag force will be higher.
scottf200
Well-Known Member
Quote: Turns out an aerospace engineer had the same question and ran the Cybertruck through CFD software (computational fluid dynamics, a computer version of a wind tunnel) to find out whether the truck drives like a brick — or only looks like one.
Aerospace engineer Justin Martin built a model of the truck from every angle he could see in photos and video of the event. Martin says he researched photos and videos from all angles for around 24 hours before running the simulation. While not everything is perfect, the general body shape of the car is as close as he could get it.
He declined to share a Cd (coefficient of drag) number because his assumptions with the wheels and fenders could affect the result significantly, such that his results were likely conservative. Cd numbers have gotten more popular lately as a rough measure of how efficient a car is (though they don’t mean everything — cross-sectional area is also important).
Martin sent us the results of his Cybertruck aerodynamic study, which you can see below:
Via: Are the boxy Tesla Cybertruck's aerodynamics any good? An engineer found out - Electrek
Aerospace engineer Justin Martin built a model of the truck from every angle he could see in photos and video of the event. Martin says he researched photos and videos from all angles for around 24 hours before running the simulation. While not everything is perfect, the general body shape of the car is as close as he could get it.
He declined to share a Cd (coefficient of drag) number because his assumptions with the wheels and fenders could affect the result significantly, such that his results were likely conservative. Cd numbers have gotten more popular lately as a rough measure of how efficient a car is (though they don’t mean everything — cross-sectional area is also important).
Martin sent us the results of his Cybertruck aerodynamic study, which you can see below:
Via: Are the boxy Tesla Cybertruck's aerodynamics any good? An engineer found out - Electrek
Uncle Paul
Well-Known Member
Don't believe that Tesla would send us a vehicle with poor aerodynamics. They have access to computational simulations they use during the design phase and also to tweek the final designs. They also have access to wind tunnels, and usually use small models early on in the design stage to address aero issues.
Of course, with the bed open and perhaps a ATV in there things could be different, but looks like this is just a made up issue.
Of course, with the bed open and perhaps a ATV in there things could be different, but looks like this is just a made up issue.
Doggydogworld
Active Member
For the same cross-sectional area, yes. But the truck is taller than the X. The ratios look similar to me (15% longer and taller).
The gradual rear taper is a big win, no doubt.
I'd need a lot of convincing on this.
Even in the production version?
The wheel areas are a mess. Justin's CFD model has flush wheels with no protruding wheel well arches. He also has flush side windows vs. the problematic inset windows on the concept truck. That's not a criticism of his model - it's just a first pass. A more detailed one would require much more time and detailed measurements he can't access.
IMHO Tesla has a design with much slipperier wheels/arches and LRR tires, similar to this CFD model, but they didn't look nearly macho enough for the reveal. Expect the look (and specs?) to evolve.
That's the intention. Tesla is one of a group of auto makers that have already started lobbying the government to catch up to the rest of the world on this front and allow camera/screen mirror equivalents. This is at the point of the NHTSA seeking public comment already
Tesla, Alliance seek U.S. regulators' OK to ditch side mirrors
U.S. to test mirrorless, camera-based systems in autos
Should cameras replace car mirrors? NHTSA wants to know
Regulations.gov
Getting back to reality how much do we really actually care what the aerodynamic numbers are it it practical to even care as long as it produces the range/speed/torque numbers promised to within the same accuracy as their existing models. Again the shape is a design constraint so it's pretty much guaranteed that any aerodynamic deficiencies are understood and factored in and/or made up for elsewhere. What does the Cd actually change here?
Tesla Cybertruck - Is it more streamlined than it looks?
.48 and that still doesn't have side mirrors. This is what the OP was talking about. .48 isn't terrible for a 20 year old pickup but it will be the worst 2022 full size pickup on the market in that area.
Ditch the wheel flairs, keep the tires inside the body, and flatten the roof and they will have it. At .48 the 500 mile version is going to need a 225 kWh pack, maybe even more if they keep the aggressive mud terrain tires.
.48 and that still doesn't have side mirrors. This is what the OP was talking about. .48 isn't terrible for a 20 year old pickup but it will be the worst 2022 full size pickup on the market in that area.
Ditch the wheel flairs, keep the tires inside the body, and flatten the roof and they will have it. At .48 the 500 mile version is going to need a 225 kWh pack, maybe even more if they keep the aggressive mud terrain tires.
JRP3
Hyperactive Member
Some were just about right....
OP and some others...not so much.
No matter what the end results it is going to be the best (aerodynamic) truck on the market.
OP and some others...not so much.
No matter what the end results it is going to be the best (aerodynamic) truck on the market.
Yup, put the CT into a wind tunnel and compare to the F-Xxx trucks.
I fail to see the scientific validity of hand drawings with color shading, and/or the cd listings of shapes, as being supportive for the OP's debate. Our order is to replace an F250 PSD with this CT electric torque monster. We're not Tesla fanboys or girls, or eco-warrior greenies, but we probably WILL be now.....
I fail to see the scientific validity of hand drawings with color shading, and/or the cd listings of shapes, as being supportive for the OP's debate. Our order is to replace an F250 PSD with this CT electric torque monster. We're not Tesla fanboys or girls, or eco-warrior greenies, but we probably WILL be now.....
Uncle Paul
Well-Known Member
^this
And compare to other ev’s like rivian, and lets throw in Bollinger for fun (this one I’d expect high cd)
MichaelP90DL
Active Member
Once you take delivery, find a cop with a radar gun. Tell the cop to park to switch on the radar and keep it running continuously. On a long, flat, straight and empty road, approach the radar gun. Have the cop flash his lights when he "acquires" the CT. Then note the distance from the acquisition point to the radar gun. Back when I was in the radar jamming biz, a half mile was the common distance of acquisition. If you can get closer than that, congratulations. A good radar detector will pick up the radar signal well before the gun can pick you up. I could tell you some really comical stories about what we did with police radar guns.
