Elon Musk says the new Tesla Roadster will hit 60 MPH in less than 1 second. Don't count on it

 

The second-age Tesla Roadster is back in the news after Elon Musk announced that the vehicle will hit 60 miles per hour in less than a moment. That's almost a full second faster than the previous record holder, which made me wonder: Is that really conceivable? I calculated to find a solution: It is indeed possible, but it would be so embarrassing that the whole enterprise would not be worth the trouble. How about we meet, what I found.

In 2021, when Musk was guaranteeing the Roadster would go from zero to 60 in a stumbling 1.1 seconds, we actually took a look at his work and found that it could hypothetically work — in the unlikely event that Tesla replaces the rear seats with a huge compressed air tank and blower. However, with this new case, I went back to restore those numbers and check that they really held up.

 Elon Musk says the new Tesla Roadster will hit 60 MPH in less than 1 second. Don't count on it

In the first place, we will list the realities that we know. The Roadster can hit 60 in "short one second," which definitely means 0.99 seconds at most. Out of the liberality of my heart, that's the number we're working off for a 2.763g increase in speed. We know from the specs that the Roadster puts 10,000 newton meters of force at the wheels, however we don't have the foggiest idea of ​​the vehicle's weight. In fact, we realize that the battery alone weighs around 1,800 pounds, while the gauges for the vehicle's weight territory from 3,500 to 4,100. I went with 3,900 because it's the two inside that reach and the Nissan GT-R's estimated weight — strong scale to increase speed.

First, we want to find out what power the vehicle can provide from its own electric powertrain. Using this figure of 10,000 Nm and the size of the tires (obvious in some of the press photos, provided you really zoom in) we can calculate that the electric drive provides 27,435 newtons of power, which is enough thrust to favor a vehicle with 3,900 pounds. A speed increase of 1.58g. That in itself is nothing to laugh at, but hitting a 0.99 second target adequately is not. This will require an additional 1.183 g provided by another of Musk's organizations: SpaceX, with its compact air tanks, cold air engines. To this end, we look back at the work of Dr. Stephen Granade from 2021:

But how powerful are cold air engines? What could be equated to environmental friendliness is classified as "explicit driving". The higher a particular rocket engine drive, the more productive it is. Explicit driving is estimated in short order, which sounds unusual until you understand that the specific motivation is to answer the question, "How long can a particular engine, using a particular fuel, accelerate its own weight to one g?" Hawk 9's most memorable stage uses engines with a special motivation of 280 seconds of drifting level.

A viral air engine using air? Since air is generally nitrogen, I will include a specific motivation for a nitrogen engine: about 70 seconds.

That's...not very eco-friendly. However, is it enough? To solve this we really want to sense how much pressure we really want and considering how much air the engines will pass pushing the vehicle with that amount of compression.

Another way of saying "push" is "infinite force is the equivalent of weight multiplied by an increase in velocity. I expect the Roadster to accelerate with a consistent increase in speed, which is most likely not correct, but it's close enough to my motivations. to get to 60 MPH in 1.1 seconds, the vehicle needs an increase in velocity of more than 24 meters per second squared, or nearly 2.5 g. Going back to high school physics, we realize that the power required will be that the speed increases times the weight of the vehicle. The battery pack can be around 800kg so I expect the vehicle to be around 1600kg. That means the vehicle needs almost 39,000 newtons of thrust to reach that speed.

Despite the fact that the engines are not the main thing that pushes the vehicle. Bargaining evidently can accelerate the vehicle to 60 miles per hour in 2.1 seconds. That's something to do, they should give a power of around 20,000 newtons. Expecting the engines won't cause the tires to lose their grip, which conveys the 19,000 newtons of power the engines can deliver.

Stephen and I contrasted in the initial math (things like the weight of the vehicle and how much power the electric drive gives), yet the differences balance out a lot. His estimates resulted in a shortfall of 19,000 newtons, while my shortfall of 1.183g calls for 20,254 newtons - which is almost enough that the rest of the math doesn't change much. So we should explore what it actually resembles:

 The thrust of the rocket rises to its particular motivation times g times how fast the rocket engine removes mass. In order to achieve the required pressure, the engine must constantly release almost 27 kilograms of air. The Roadster will, as far as anyone knows, use 10 engines, not just one, but that simply means each engine will expel 2.7 kilograms of air every second. All the air needed every second remains similar.

(By the way, air will come out of the engines at about 1,500 mph. Try not to change lanes too close to another vehicle when you shut down those engines!)

In case you simply use the engines to reach 60 MPH in 1.1 seconds, you will need 30 kg of air. For normal pneumatic stress, you would need a tank the size of a steel trailer. In any case, Tesla uses compressed air stored in a SpaceX pressurized vessel, known as a COPV. SpaceX COPVs maintain nitrogen at 6,000 psi. At this voltage you can get the air you want into the 55 liter chamber.

55 liters is the same as 15 gallons. That's not terrible! A COPV the size of a small domestic water heater would be sufficient. Tesla envisages removing the two rear seating arrangements to account for the COPV (), which I estimate will leave room for a 140-150 liter tank.

Regardless, being in the neighborhood of thinkable isn't exactly the same thing as being functional. The voltage inside the COPV will decrease as the air leaves the engine, so you will need more than 55 liters of air. More pitiable, however, will be the tanks. Tesla suggested they use an electric siphon to refill the tanks:

Try to find a suitable electric air blower that can top off the tanks to their 6,000 psi pressure. More ominously, the higher the resulting pressure, the slower the tank fills. You can find these high voltages in scuba tanks, so I also looked into scuba air blowers. HPDMC makes one that has a working stress of 4,500 psi. It would take over two hours to fill our 55L tank. In addition, it consumes 3000 watts. That's a ton of power, but you can swap it out for one from BEAMNOV or Orion. They only use 1,800 watts. Obviously, currently it would take four hours to refill the tank.

You might think of blowers like those tracked down in carports and studios - noisy, rattling and out of order - but you can definitely relax, the blower needed here isn't what's going on. Most car air blowers only push air to about 150 to 200 psi, well below the 6,000 that Roadster owners carry right behind their heads.

That's all hypothetically imaginable, but reasonably silly thinking, which Musk seems to appreciate — promising to bring science fiction to the real world, whether it's really smart or not. The Roadster can basically, assuming it arrives at any point, hit 60 miles per hour in less than one second, but the cost of doing so will be perfect to the extent that everything works.