Those silly jets

[D.E.]

I keep reading about those “jets” that are going to make the roadster quicker. The last said the license plate would drop down and the high pressure air would then drive the car forward.

Any idea how much high pressure air would be needed to push a 5000 pound car forward. And what about anyone parked or standing in the air blast zone. The weight of the hardware for that high pressure air compressor and storage tanks seems unlikely to result in a net positive for acceleration let alone handling. To vent meaningful amounts will be very noisy.

The whole idea seems absurd to me. Why not spend that extra weight and that money putting in a 4th motor?

 

[ThomasD]

It would probably need close to 200 lb of force to maintain a speed of around 60 miles an hour. You have to figure in the frontal area of the car. The co efficient drag of the car and the rolling resistance of the tires

 

[Uncle Paul]

This is a track use only option. Not practicle for street use.

Will need to delete rear seat to carry necessary gear. Mostly powered by vehicle regeneration system as well. This additional regeneration capability will also be a giant advantage by taking much of the decelleration load off the brakes.

Big jet out the rear will give an instant pulse of acceleration off corners, verticle jet will add welcome downforce in the corners, as well as horizontal jets to provide additional stability control under high G turns.

They are not intended to have any practicle benefits in normal street driving.

 

[Chaserr]

The whole idea seems absurd to me. Why not spend that extra weight and that money putting in a 4th motor?

Theoretically, they can enhance braking and cornering if they fire the jets up instead of just back, helping the tires grip more without making them physically wider. Another motor is probably better than those license plate jets but if they fire some up to make the tires work harder they could help hide some of the battery's weight when it comes to handling. That is more important than acceleration on the track - not slowing down is better than speeding back up a a little faster.

 

[AMPd]

This is a track use only option. Not practicle for street use.

Will need to delete rear seat to carry necessary gear. Mostly powered by vehicle regeneration system as well. This additional regeneration capability will also be a giant advantage by taking much of the decelleration load off the brakes.

Big jet out the rear will give an instant pulse of acceleration off corners, verticle jet will add welcome downforce in the corners, as well as horizontal jets to provide additional stability control under high G turns.

They are not intended to have any practicle benefits in normal street driving.

Can you post proof of that please?

 

[Kevy Baby]

Can you post proof of that please?

Why let a lack of evidence get in the way of a perfectly good rumour?

 

[iwannam3]

Ever cracked the valve on an O2 tank? Comes out at supersonic speed and makes a hell of a lot of noise.

 

[ThomasD]

What will the compressed air tanks and related hardware weigh? After they are empty you will have to refill them I would not want to be in that car if a tank got punctured

 

[Uncle Paul]

I had the great pleasure of being able to push a Chaparrel race car into the pits at a track event. It had a snowmobile engine in the rear that powered a fan to evacuate air from underneath the car. It had skirts all around the sides and rear. This additional suction/downforce allowed it to out corner every other car on the track.

It was soon outlawed by the sanctoning body, but when it was legal it was far faster than anything else in it;s class.

 

[n2mb_racing]

It does seem incredibly stupid. I definitely won't be ordering that option. I need a rear seat to carry a child. That's why I had to sell my original Roadster....

I would prefer that they finish the car sooner, rather than waste time on silly things like gas thrusters.

 

[Skyball]

Here's a good explanation of the math and physics - 0-60 in 1 second!

 

[D.E.]

Here's a good explanation of the math and physics - 0-60 in 1 second!

He claims 66 pounds of compressed air for each second of use. That’s three 130 lb compressed air cylinders plus the 66 lbs of air. So about 450 pounds of extra weight, and that’s before the equipment needed to pipe and vector all that gas. If you want to have the equipment needed to compress all that gas on board, that’s a lot of additional weight as well. Then there are the thermal concerns of gas fairly suddenly being decompressed from 2200 PSI to ambient pressure. Compressing that gas will produce a lot of heat. If you’ve ever seen what damage is done when a scuba tank explodes, multiply that by 30 or so, and put this bomb into a race car racing around a track at what, 170 mph? What could possibly go wrong?

I’d love to be wrong. I’d like to see a Tesla firing off jets of compressed air going around a track absurdly quickly. Then as a bonus, lifting off the ground a few inches, blasting big divots out of the road, spraying sharp lumps of high speed asphalt in all directions. I think I’m not wrong, though. This wasn’t well thought out. Someone needs to put down the funny cigarette and pick up a calculator.

 

[ThomasD]

Not to mention you will have to periodically drain the tanks if they still have air in them to prevent corrosion in the tank. These tanks are nothing to play around with Watch at the 1:30 mark

 

[ThomasD]

You will have to have some sort of dryer system to keep moisture out of the lines If the valve becomes damaged it can turn the cylinder into a missile. There is no way Tesla will take on the liability of this setup

 

[Kevy Baby]

...plus the 66 lbs of air.

How is there a weight to air?

Not trying to be facetious; I am seriously confused by this.

 

[mongo]

How is there a weight to air?

Not trying to be facetious; I am seriously confused by this.

Air has mass, just like all matter. 1.225 kg/m^3 (.0765 lb/ ft^3) at 15C sea level.

 

[mongo]

Mostly powered by vehicle regeneration system as well. This additional regeneration capability will also be a giant advantage by taking much of the decelleration load off the brakes.

Not tied to drive unit, uses additional motor.
Elon's Tweet on the subject:

Using the config you describe, plus an electric pump to replenish air in COPV, when car power draw drops below max pack power output, makes sense. But we are going to go a lot further.

Twitter

 

[VegasBlue]

First of all, I was quite impressed by the physicist's video. Quite level headed and sensible from a mathematical point of view, given the limited information we know.

As a physician (not a physicist) the most alarming part is not the acceleration, but the Deceleration, which can be particularly harmful to the human body. Rapid deceleration is not fun; it doesn't feel good which is why you don't see it in amusement park rides, and can be fatal. And the potential harm increases with age. As a single example, the aorta is the biggest blood vessel in your body. If it bursts, you die in seconds. With hard acceleration the aorta is pressed back against the spine, and is safe. With hard deceleration it rips off its small tethering points as it moves forward in your body and bursts. Similar occurrences happen in your eyes, brain and stomach. Now a 2.4 g deceleration is obviously not as severe as slamming your car into a stationary object, which is where I see most fatal car injuries, but it makes one wonder what the long term effects might be with repeated occurrences at the track. Perhaps cars equipped with the space X option should be fitted with 5 point harnesses.

 

[Saghost]

I had the great pleasure of being able to push a Chaparrel race car into the pits at a track event. It had a snowmobile engine in the rear that powered a fan to evacuate air from underneath the car. It had skirts all around the sides and rear. This additional suction/downforce allowed it to out corner every other car on the track.

It was soon outlawed by the sanctoning body, but when it was legal it was far faster than anything else in it;s class.

Now that’s an interesting idea. Tesla already has very flat sealed under bellies. I wonder if they can get the same downforce advantage for less weight and energy by creating a partial vacuum under the car, either by sucking the air out or through Bernoulli effect suckdown from pushing the air underneath sideways.

 

[mongo]

First of all, I was quite impressed by the physicist's video. Quite level headed and sensible from a mathematical point of view, given the limited information we know.

As a physician (not a physicist) the most alarming part is not the acceleration, but the Deceleration, which can be particularly harmful to the human body. Rapid deceleration is not fun; it doesn't feel good which is why you don't see it in amusement park rides, and can be fatal. And the potential harm increases with age. As a single example, the aorta is the biggest blood vessel in your body. If it bursts, you die in seconds. With hard acceleration the aorta is pressed back against the spine, and is safe. With hard deceleration it rips off its small tethering points as it moves forward in your body and bursts. Similar occurrences happen in your eyes, brain and stomach. Now a 2.4 g deceleration is obviously not as severe as slamming your car into a stationary object, which is where I see most fatal car injuries, but it makes one wonder what the long term effects might be with repeated occurrences at the track. Perhaps cars equipped with the space X option should be fitted with 5 point harnesses.

5 point is a good idea.
Relatedly:
Colonel John Paul Stapp, 46.2 g deceleration, forward facing, well secured.
John Stapp - Wikipedia