Tesla Cybertruck vs. a Ford F-150: It's All About Friction | Hacker News Reader

Tesla Cybertruck vs. a Ford F-150: It's All About Friction

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I'm normally not one for "conspiracy theories", but I can't shake this idea that there might be some really clever marketing happening here.

Tesla releases a "clearly one-sided" marketing video, and waits for the inevitable backlash from social media. Secretly Tesla knows their truck will win in just about any 1v1 competition with a Ford (at least when it comes to towing power or max torque), so they just wait for more impartial tests which will all reaffirm the results from the first. And then they get to not only extend how long people are talking about it, but they also get "impartial" tests which can help convince those who don't trust Tesla at all.

I mean it's one thing to see Tesla show that they can tow more, but it's another to see your favorite auto blogger or tv program show it.

And at the end of the day this is just another good rivalry, which I absolutely love! I love seeing Porsche and Tesla take shots at one another about performance around the ring, and I'd love to see Ford and Tesla get in a similar battle. Each company one-upping the other with every release, each one trying to make the better vehicle both on paper and in various tests.

The goal is not for Ford to bring out their beefiest ICE pickup to try to win. It is to force them to bring out their EV prototype F150 model, as it's the only way to "win" against Cybertruck (due to friction, torque, etc). An unloaded F150 with an internal combustion power train and traditional torque converter is never going to beat an EV with a 1200 lb battery and torque from 0 RPMs (Cybertruck is putting down at least 1000 ft lbs of torque, perhaps more, based on a tri motor config).

Tesla can't build a million electric F150s a year (~1 million internal combustion F150s are currently sold each year). Ford can. They might even buy powertrains from Tesla. Ford's EV team should send a nice gift to Elon.

>An unloaded F150 with an internal combustion power train and traditional torque converter is never going to beat an EV with a 1200 lb battery and torque from 0 RPMs

Put the F150 on some high performance season specific tires and put the Tesla on some economy brand E-rated all seasons and the F150 will win every time and it won't be obvious to 99.9% of observers.

This is not how the friction coefficient works. Swapping tires isn't going to negate the weight differential between an ICE truck (heavy engine, empty bed over half the drivetrain) and an EV battery pack applying downward force across the entire sled, nor EV traction control vs a torque converter and the disadvantaged mechanical transmission attempting to vector torque. "Physics is the law, everything else is a recommendation."

Fundamentally, an internal combustion powertrain is an inferior mode of locomotion (efficiency losses all the way from the well to the cylinders to the wheels), and energy storage has finally caught up to support the rest of the superior (and arguably, more simple) powertrain an EV provides (Train locomotives have used electric motors for decades, with a diesel generator; there is no transmission that exists that can reliably distribute that torque, for example).

>This is not how the friction coefficient works

Yes, it very much is. The harder tire has a lower friction resulting in the total force to break static friction being lesser than that of the lighter object with the higher friction tires. Go get some cleats and push a heavy object around on ice if you want to see this in action.

> the weight differential between an ICE truck (heavy engine, empty bed over half the drivetrain) and an EV battery pack applying downward force across the entire sled,

The weight transfer (when the truck tries to rotate the wheels and can't the truck tries to rotate about the rear axle) mostly negates this. Watch some videos of pulling trucks and tractor. By your reasoning the massive weights they hang in front of the front axle would be counterproductive because they would remove weight from the rear axle. In practice enough of the weight transfers to the rear axle to result in a net improvement.

>nor EV traction control vs a torque converter and the disadvantaged mechanical transmission attempting to vector torque.

Your statement is fantasy. Both systems are inputting torque to a differential (presumably an open one since these are base spec 2wd models). The traction control is going to modulate the brakes on the spinning tire to fudge the same effect as a more conventional traction aid installed in the differential would provide.

Electronic traction control introduces yet another variable to the equation, some traction control systems behave like an electronic nanny and cut throttle. Some just assume the customer is right and slam the brake on the spinning wheel. I'm going to assume they both have the latter type because it makes this comparison simple but any vehicle equipped with the former type is going to be at a disadvantage.

That's not what "conspiracy" means.

But yes, it could absolutely be intentional marketing. How would we know what his intentions were? Or are we just crediting Musk with the eventual results?

For me it was either your theory above or they slapped the prototype together in a very short period of time and just grabbed the first F-150 an employee volunteered.

It does setup a perfect situation where they slowly ramp up the stakes ending with it dragging an F350 backwards or something.

>Secretly Tesla knows their truck will win in just about any 1v1 competition with a Ford

i'm not sure how this counts as clever marketing? making a product that's legitimately better than the competition is the opposite of clever marketing.

Making a better product isn't marketing. Making everyone aware your product is better is, though.

A superior product can be marketed poorly, right? Well this is must a superior product and good marketing.

If I understand them correctly, Klathmon is claiming that the marketing dept at Tesla is leveraging Cunningham's Law to get free publicity from reviewers/bloggers/you-tubers.

Indeed, this doesn't show which truck is more powerful / greater torque. It shows which truck is better at towing, which is arguably more relevant for a truck. Greater mass also means greater control while towing.

I don't think it's showing anything more than an entertaining bit of marketing. There are plenty of ways it could be terrible at towing but still appear better at this test.

More importantly, the wider wheelbase will be important for towing. Long, tall trailers (like RV's, or long cargo trailers) get a lot of wind force, and on smaller tow vehicles (SUV's and smaller trucks) you can get in a very dangerous situation where the tail wags the dog. For a similar reason, the heavier weight of the Tesla truck will help at stability when towing.

Towing has more to do with braking than anything else.

Isn't regenerative braking amazing?

Braking is also a question of traction. Pretty much all brakes can apply a much greater force than the traction at the wheels, hence the motivation for anti-lock breaking systems. Having the truck be more massive relative to the trailer improves the breaking performance.

A more relatively massive truck also helps reduce the propensity for jackknifing.

I think the issue with this display is the weight distribution. The Tesla is loaded down with batteries and the Ford bed is empty so it's real wheels start to spin immediately and friction of tires on road goes way down the moment that happens. I wonder if the Ford was 4WD if the front wheels would have made it more difficult for the Tesla. At any rate, it's kind of pedantic at this point, both trucks are probably good at pulling stuff, but it is interesting.

If they could have pulled a 4wd they likely would have.

> I wonder if the Ford was 4WD if the front wheels would have made it more difficult for the Tesla

From the video you see the front wheels rolling back, rather than trying to grip forward. This was rear wheel drive.

Engineering Explain has a fantastic whiteboard breakdown of the maths: https://www.youtube.com/watch?v=jzKCJsou10w

I like my pet theory: the Cybertruck has a much lower level of detail; this frees up more resources for pulling things.

Elon tweeted that even if the beds were loaded the Cybertruck will still win. Seems plausible to me given the enormous torque of electric engines. But I'd love to see the battle!

Did you read the article? Of course it would be the same result if they put equal weight in the truck beds. The key is the weight, not the torque.

So what, though? The Tesla will won do its weight and weight distribution. Does it not count because it’s not purely due to torque?

Even if you weighted the F150 up to match the weight of the Cybertruck, the Cybertruck would almost certainly still win. Electric motors have much higher starting torque, and as soon as the F150's wheels start slipping, it would be game over. Dynamic friction is much lower than static friction.

It's silly to say "it's just friction".

Friction is what allows the application of that torque into something actually meaningful. But a $39K Cybertruck being better at some things than a $28K F150 shouldn't be surprising. Bumping it up to at least a $35K F350 makes the comparison at least reasonable spec-wise.

It's not apples to apples. I'd like to see a 4 wheel drive F-150 vs the Cybertruck with equal weight.

>Elon tweeted that even if the beds were loaded the Cybertruck will still win.

Load them both down with a couple yards of sand and whichever one doesn't break some drive-line component is gonna win. Considering nobody's torn down and reviewed a Tesla truck yet it's kind of hard to say which but I feel very safe saying both trucks have more than enough power and torque at zero (wheel speed) rpm to break things given the kind of traction a couple yards of sand makes availible.

The Cybertruck started pulling first. I wonder what would happen if the F150 started first, and had the Cybertruck moving before it started to pull itself. I wonder if this is an example where they had the order right...

Im also wondering if both vehicles had 4 wheel drive engaged. I'd love to see these 2 vehicles really square off.

The Verge reported that the F-150 was a RWD model.

You can see this in the video, even. The front wheels of the truck are rolling backwards as it's being pulled.

Anyway, the bit about who's being pulled first also interests me; anyone else wondering about the difference of static vs dynamic friction of rubber on pavement?

I'm pretty certain you're right that, as expected, for tires on pavement, static friction is great than dynamic friction.

That is certainly what I've observed in my own firsthand experience.

Also, as I understand it, it's why anti-lock brakes help a car stop faster. (Though anti-lock brakes also help you retain the ability to steer, which is different but also important.)

In the video you can clearly see just the rear wheels spinning on the F-150; e.g., it was RWD.

One other bit about the mechanics of it-

If the two trailer hitches are not exactly level with eachother, whichever truck has the higher hitch has a big advantage.

Is the Cybertruck 4wd? That F-150 certainly was not.

single motor is RWD dual and tri motor are all wheel drive according to this page.

https://www.tesla.com/en_gb/cybertruck

What kind of realistic test is a truck tug of war? Do a test where you load the beds and another test with a heavy trailer. Put comparable tires on the f150 instead of mall crawlers. Take it through paved roads, an incline, unpaved roads, and maybe some snow or ice. All of this is just PR.

We all know the electric motor with have a torque advantage. What we don’t know is when the CyberTruck will over heat.

Does the Cybertruck have a clutch pack for AWD or have a low gear like the F150? What about a locking rear diff? Ask some Subaru owners what happens to their clutch pack when they did some serious off-roading.

Clearly, they need to take the electric Ford F-150, the Tesla Cybertruck, and this 1 million pound train, and hook them all together for a proper test.

https://www.youtube.com/watch?v=bXFHgoon7lg

(The above demonstration with low rolling resistance is also not a great way to show how well a vehicle can pull things, at least not in scientific terms!)

Seems like if you really wanted to compare you would have both trucks tow the same loads and then report back on things like range etc. for each different load.

That doesn't make for a viral video though.

Right, this further indicates F150 is inferior, as it does not even have enough friction to compete, let alone HP and torque

That friction is relevant most when it's loaded, which is arguably the main use case for a pickup truck. That was not tested in this case.

In the article, it talks about how the weight of the vehicle is one of the greatest factors in determining friction, and weight is not a universally superior factor in trucks.

(It is for specific tasks, and up to a certain point, but there's a reason why Ford replaced their steel bodies with aluminum.)

In other words, given that the Cybertruck wins on torque, there may be better ways to demonstrate it than showing that it's heavier (as stated in the article.)

No. That's just an unequal comparison of different classes given the significant differences in size, weight, and price. Why not compare the to an F350 then?

This isn’t much different than the truck commercials with contrived pulling “demonstrations” that Ford, Chevy/GMC, and Dodge have peddled for years. Good on Elon to troll them a bit.

I'd bet that Tesla has it batteries over the rear axle. Toss a load of gravel in the back of the F-150 for a better comparison.

It probably uses the same skateboard design for the battery pack that all of Tesla's other vehicles use. The battery pack spans nearly the entire bottom of the vehicle, giving it a low center of gravity which helps prevent tipping and provides more trunk space.

Is it really a better comparison though? What is being compared? Seems like a legitimate design decision.

That Tesla had better be good. Like circa 2013 Model S good.

Otherwise, the ugliness will make owners total laughinstocks.

> As long as both vehicles have sufficiently powerful engines, the more massive one will win.

I know they're trying to write an accessible article here and they probably realize this, but that is a simplified version of the physics.

So just to be clear, since the vehicle has 4 wheels, and the force due to gravity (proportional to mass) is distributed among them, you need to individually analyze the situation for each of the wheels. You can't treat the vehicle as a single unit.

Things are going to fall apart when the first one of the drive wheels loses traction. (From there, things get strictly worse because the other drive wheels take on more of the burden.) So that means you need to consider the normal force on each wheel.

And you need to consider the power delivered to each drive wheel and the control systems that achieve this. It's entirely possible the Cybertruck has an advantage here because electric motors might very well allow more precise and faster control of power applied than you can achieve in an ICE vehicle. (I'm not a car expert but I believe ICE vehicles apply brakes if the force gets too much because that allows better, faster control than varying the throttle. So that's an improvement, but I doubt it gives control as good as an electric motor.)

TLDR: Mass matters, but so does weight distribution and so does the quality of traction control. All of these could be factors which differ between F-150 and Cybertruck.

s/friction/traction/

True, although the main thing they're trying to say is it's not about power or torque.

Draw all the free body diagrams you want, barring massive disparities in size, obscene inclines or crazy tow rope angles (i.e. "in any reasonably even competition") the vehicle with the better tires will win every single time.

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