r/SipsTea • • 23h ago

SMH Museum of Useless Inventions

Post image
16.7k Upvotes

2.9k comments sorted by

View all comments

375

u/TheCerpent 20h ago

I am constantly baffled by the people taking that demo at face value.

That's not a real car. It's a hollow shell shaped like a car. The speed and precision it moves entirely suggest a lightweight object, especially since we don't see any flames or other indication of high powered jet fuel coming out of those nozzles.

It is physically impossible for a 1.5 ton vehicle to make that sort of leap with jets with that little buildup and that little apparent power. Momentum is a BITCH. Think about how much time it takes to get your car up to speed, or make a quick turn. The math ain't mathin'.

Questions of street legality or even entering any sort of production model aren't even in the picture here. This was an expensive tech demo of a fancy toy that isn't even a car, and they're trying to pretend it's an actual car. Think about the fact that they never show you the interior of it either immediately before or immediately after it does the stunts. That's because there's nothing inside.

If you believed it was real, you fell for the con.

5

u/Romeo9594 19h ago

I really want to know, if they made anything real like what they showed off, how much pressure would be in the tank in order to do what what was shown with an actual EV. Like do we really want to be driving around with the next best thing to a bomb in the back seat?

7

u/TheCerpent 19h ago

Well, think about it this way. Let's assume that the vehicle weighs around 3000 lbs, or 1.5 tons. If that's the case, the jets would need 1.5 tons of thrust to merely -equal- the mass of the vehicle. That's not enough to lift it. It would require even more thrust to push it upward. To push it upward at that sort of acceleration would likely take an order of magnitude more thrust.

To do that midair flip? That's right, something powerful enough to rotate 1.5 tons of machine without sending it crashing into the ground. Then, to land softly, still putting out massive forces to counteract gravity and prevent damage to an incredibly heavy vehicle. And that sort of force likely would have been reflected on the vehicles the "car" jumped over.

The fact that they used cold gas thrusters is basically the final proof that this isn't a real car. It would need something far more powerful to move something of real mass, which is why I mentioned jet fuel or rocket fuel. Which brings us to the biggest problem of all: the inverse square law.

Basically, if we need rocket fuel to do the jump, then we need to account for the weight of the fuel. Which means we aren't solving for a 1.5 ton vehicle anymore, but rather a 1.5 ton vehicle AND the weight of the fuel necessary to perform the stunt. Which means we need more thrust, and thus means we need more fuel, which requires more thrust, etc. It does finally reach an equilibrium point, especially if you have particularly efficient thrusters, but the space and fuel required to pull this off would likely exceed the remaining internal space of the car, meaning you couldn't even drive the damn thing.

1

u/amsync 17h ago

So what is the point of demoing a concept car that cannot even be made real?

3

u/Inexorabilis 17h ago

Selling an idea, and selling the car later. It’s an advertisement.

3

u/Jessir12 17h ago

Pushes up the hype & stock price?

3

u/Haunting-Ear875 16h ago

Isn't that Elmo's schtick? Promise things are just around the corner. Except this time he can feign its actual existence fairly convincingly

3

u/t65789 16h ago

Elon Musk is our version of P.T. Barnum.

2

u/redneck-it-guy 13h ago

Car companies have always made one-off concepts to show off and get attention. 

Most of them don't start taking preorders. That is an Elon thing that comes from tech bro culture. 

For everyone else, some of the ideas eventually make it to production cars after the tech is refined.

1

u/Bannedagainnohomo 16h ago

Sir, I don't know those words. Inverse square...

0

u/Equivalent-Process17 9h ago

You describe why it's an awesome technical achievement but hate Elon so much you refuse to believe your own eyes