The Physics Behind That Tesla Model X Towing A Boeing

MAY 24 2018 BY DOMENICK YONEY 12

It’s not size that matters, but the force of the friction

Last week, Australian airline company Qantas gave the world a video of a Tesla Model X towing one of its Boeing 787-9 Dreamliner aircraft across the tarmac of the Melbourne Airport. According to them, it’s the first time the stunt has been pulled (no pun intended) using an electric vehicle.

While it’s a pretty great party trick, did you stop to think about the physics at play here? No? Well, neither did we. However, physics guy Rhett Alain did, and wrote about it for Wired. So, how is it that a vehicle rated to tow a mere 5,000 lbs can haul an airplane that weighs 286,601 lbs?

According to Allain, it’s mostly about overcoming the force of friction. In this case, friction arises where the wheel rotates on its axle, and rolling friction is produced by its wheels moving over the ground’s surface. Here, we’ll let the expert explain that rolling friction part:

If you look at a tire closely, you will get a good sense of how rolling friction works. Although it looks round, it’s not. The bottom of the tire is flatter than the rest of the tire because it’s pushed against the ground. As the wheel rolls over, a new part of the tire has to be flatter—and it takes a force to deform this tire. That’s the basic idea of rolling friction.

Got that? Good. Now, to move this bewinged behemoth takes torque — something electric vehicles are notably blessed with. But it also takes something else: mass with which to create frictional force. Imagine gearing a motorcycle (an electric one, of course) so that it produces the same 487 pound-feet of torque as the Model X. There’s a good chance the Boeing wouldn’t budge, and the back wheel would just turn in place, creating a smoke show.

Luckily for the electric SUV, it’s got a pretty massive battery pack, allowing the vehicle to weigh in at 5,381 lbs and create plenty of its own frictional force. Could an SUV powered by internal combustion done the same thing? Possibly, depending on its ability to produce torque. Indeed, Chevrolet produced a commercial back in the day featuring a new-at-the-time 1972 C-10 pulling a 747. You can watch both  feats of physics below. If you want to get a more thorough understanding at the forces at work here, check out this piece on Wired.

Source: Wired

Categories: Tesla

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12 Comments on "The Physics Behind That Tesla Model X Towing A Boeing"

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Spin

A Tundra pulled the Space Shuttle.

bro1999

Hell, a man pulled a plane. With his TEETH! Now that’s news!
https://www.mirror.co.uk/news/weird-news/strongman-sets-world-record-pulling-1979125

Ambulator

Friction is usually modeled as being part static friction and part kinetic friction. Once the static friction is overcome it becomes easier to keep something in motion.

If they wanted to be as impressive as possible, they would use an additional force, from something like a tractor, to get it started, then disconnect the tractor and film it.

As to whether this was done, I don’t know.

SparkEV

For shiz and giggles, you can measure your own rolling resistance by placing a bathroom scale against the bum and pushing at constant speed on level road. I measure about 40 lb, which is about 1.4% of weight.

I suspect the plane is similar, so 1.4% of 290K lb is about 4000 lb. SparkEV makes 1250 ft-lb of torque at low RPM with about 1 ft radius tire, so it can only “lift” 1250 lb. Good thing, too, wouldn’t want people abusing it by towing such porker.

rad

In the Chevy commercial, did you notice the haze? Was that fog or just the normal pollution in 1972?

Rafael Sabatini

As you note in the close, any modern SUV would be capable of performing the same feat– much like the Chevy truck did over 45 years ago.

Everybody makes a big deal out of the “massive torque” at the wheels of the Model X, but the 300 ft-lbs at the flywheel of a 350 V8, combined with two stages of gearing (first gear in the transmission plus a 4:1 in the differentials) easily turns that 300 ft-lbs into 4000-5000 ft lbs at the wheels.

The fact that people are impressed by the Model X demo says more about physics literacy than it does the vehicle.

Dave

Actually you forgot they probably had the transfer case in low range as well, which gives 3X more torque at the wheels in the Chevy. I would love to see a Modern Chevy pickup with a diesel hooked to a Model X P100D, and watch it drag that Tesla around like a rag doll, actually if the Tesla got traction, it would probably rip the Tesla in half.

Neromanceres

Fully agree. Get me 7 other people and we will pull a 787 by hand. Once you break the static friction it’s actually fairly easy to do.

rad

I think you are right. Although it did remind me of Los Angeles in the 60’s.

wavelet

The Model X story is indeed a worthless party trick. Any car can do it; it’s mostly a question of the plane’s wheels’ bearings and the friction of the surface.
A single person can, and has towed a much heavier and larger plane by hand, in 2009: CC-177 Globemaster III, which weighs 50% more than the 787 by hand, and it’s a published Guinness World Record:
http://www.guinnessworldrecords.com/world-records/heaviest-aircraft-pulled-by-a-man
The fact that PR flacks & journalists are too lazy to actually look up the subject is a problem.

aairfccha

A bit more recently than the Chevy example: A Porsche Cayenne pulled an A380.

https://www.digitaltrends.com/cars/porsche-cayenne-airbus-a380-guinness-world-record/