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Second,technology Tesla Automobile It's within the information once more after Elon Musk introduced that the automobile will speed up to 60 mph in lower than a second. That's nearly a full second quicker than that present document holder, which made me surprise: is that this actually potential? I crunched some numbers to get the reply: It's technically potential, however it will be so inconvenient that the entire effort can be nugatory. Let's see under what I discovered.
In 2021, when Musk was claiming that the Roadster would go from zero to 60 in 1.1 seconds, we checked his work And located that it may theoretically occur – if Tesla changed the rear seats with a big pressurized air tank and a compressor. Nonetheless, with this new declare, I went again to replace these numbers and see in the event that they nonetheless held up.
First, we are going to lay out the information we all know. The Roadster can attain 60 in “lower than a second”, which accurately means a most of 0.99 seconds. Out of the generosity of my coronary heart, that is the quantity we shall be working from, for an acceleration determine of two.763 Gs. We all know from the spec sheet that the Roadster claims 10,000 Newton-metres of wheel torque, however we don't know the load of the automobile. We to do Know Battery weighs roughly 1,800 kilos itself, whereas the load of the automobile is estimated by 3,500 kilos To 4,100, I went with 3,900, as a result of it's inside that vary and the approximate weight of the Nissan GT-R – a stable benchmark for acceleration.
First, we have to calculate how a lot drive the automobile can present from its personal electrical drivetrain. Utilizing that 10,000nm determine and the dimensions of the tires (seen in some press pictures, in case you In actual fact Zoom in) We are able to calculate that the electrical drive gives 27,435 Newtons of drive – sufficient thrust to bless a 3,900-pound automobile with 1.58 grams of acceleration. It's nothing to scoff at, nevertheless it's not sufficient to satisfy the 0.99-second goal. This is able to require a further 1.183 grams offered by Musk Different Different Different different firm: SpaceX, with compressed-air tank Blows of chilly air. For that, we're going to look again Work by Dr. Stephen Grenade from 2021,
Nonetheless, how efficient are chilly air propellants? The rocket equal of gasoline effectivity is known as “particular impulse”. The upper the precise impulse of a rocket engine, the extra environment friendly it’s. Particular impulse is measured in seconds, which sounds unusual till you notice that particular impulse itself is the reply to the query, “A selected engine, utilizing a selected gasoline, produces one gram of its personal In what number of seconds can the mass be elevated? The Falcon 9 first stage makes use of an engine with a selected impulse of 280 seconds at sea degree.
A chilly air blower that makes use of air? Since air consists principally of nitrogen, I’d use the precise impulse for a nitrogen thruster: About 70 seconds.
It's…not very gasoline environment friendly. However is it sufficient? To seek out out, we have now to have a look at how a lot thrust we’d like and, primarily based on that, how a lot air the thrusters will use to push the automobile with that quantity of thrust.
One other phrase for “thrust” is “drive”, and drive is the same as mass instances acceleration. I'll assume the Roadster is persistently quicker, which might be not true however shut sufficient for my functions. To achieve 60 MPH in 1.1 seconds, the automobile wants a momentum of greater than 24 meters per second squared, or about 2.5 g. Going again to highschool physics, we all know that the drive required shall be equal to the acceleration of the mass of the automobile. The battery pack can weigh round 800 kg, so I’d assume the automobile to be round 1600 kg. This implies the automobile wants about 39,000 Newtons of thrust to succeed in that pace.
Nonetheless, thrusters aren't the one factor pushing a automobile. The wheels and powertrain are imagined to propel the automobile to 60 MPH in 2.1 seconds. To do that, they have to present roughly 20,000 Newtons of drive. Assuming the thrusters don’t lose grip with the tires, this leads to the thrusters offering a drive of 19,000 Newtons.
Stephen and I’ve variations within the elementary math (issues like the load of the automobile and the quantity of drive offered by the electrical drive), however these variations are literally roughly balanced. His calculations resulted in a discount of 19,000 newtons, whereas my discount of 1.183 grams required 20,254 newtons – so shut that the remainder of the mathematics barely adjustments. So, let's see the way it seems to be in actual life:
The thrust of a rocket is the same as g instances its particular impulse instances how briskly the rocket engine expels mass. To generate the quantity of thrust we’d like, the thruster has to expel about 27 kilograms of air each second. The roadster is believed to be Use 10 thrusters as an alternative of only one, however this merely implies that every thruster will throw out 2.7 kilograms of air each second. The entire air required per second stays the identical.
(By the way in which, in some locations the thrusters will blow air 1,500 mph, Don't change lanes too shut to a different automobile if you're firing these thrusters!)
If you’re going to use thrusters to succeed in 60 MPH in simply 1.1 seconds, you will have 30 kg of air. At regular air strain, you will have a tank the dimensions of a transport container. However Tesla is utilizing compressed air saved in SpaceX's pressurized vessel, often called a COPV. SpaceX COPV incorporates nitrogen at 6,000 psi, At that strain, you will get the air you want in a 55 liter container.
55 liters is the same as 15 gallons. Not unhealthy! A COPV the dimensions of a small home water heater has this a lot capability. Tesla plans to take away the 2 rear seats to make room for the COPV (), which I estimate will depart room for a few 140-150 L tank.
Nonetheless, being within the neighborhood of admirable just isn’t the identical as being sensible. The strain contained in the COPV will drop because the air leaves the thruster, so you will have greater than 55 liters of air. Nonetheless, a worse case state of affairs can be refilling the tanks. Tesla has prompt that they are going to use an electrical pump to refill the tanks:
The trick is to discover a transportable electrical air compressor that may refill the tanks as much as a strain of 6,000 psi. What's worse, the upper the output strain, the slower the tank fills. You get these excessive pressures in SCUBA tanks, so I’d additionally check out a SCUBA tank air compressor. HPDMC manufactures a tool that has a working strain of 4,500 psi, It can take two and a half hours to fill our 55 liter tank. It additionally attracts 3,000 watts. There’s a whole lot of energy in it, however in you This may be changed with one from beamnova Or orion, They solely use 1,800 watts. After all, it’ll now take 4 hours to refill the tank.
Chances are you’ll consider compressors present in garages and workshops as loud, noisy and inconvenient – however don't fear, that's not the case with the compressor required right here. Most storage air compressors solely pack 150 to 200 psi of air, which is much lower than the 6,000 psi that roadster house owners shall be gunning straight for behind their heads.
It's all of the sort of theoretically potential however realistically absurd pondering that Musk loves – promising to deliver science fiction into actuality, no matter whether or not it's truly a good suggestion or not. Theoretically, if the Roadster is ever launched, it may speed up to 60 mph in lower than a second, however the price of doing so is so excessive that it’s going to by no means be value it.