Just kill it off already

[Earl]

It does nothing to advance the mission but distract from RoboTaxi and the Tesla compact.

That all depends on what the Roadster is in the way of. Robotaxi folks are definitely a different skillset than most who are needed to build a new automobile. Tesla compact folks probably would overlap a bit with the same ones as needed to build the Roadster. However, I suspect that the folks needed most for the Tesla compact are those who can wring every penny off of the cost while those for the Roadster would be the R&D folks who don't/can't deal with low costs but can eek out massive performance. Given the delays on the Roadster, it isn't obvious which car is getting what priority though. Both are taking time but, of course, given the halo aspect of the Roadster, it isn't surprising if it gets mentioned periodically, just to keep the buzz going.
I do wish I had those thrusters on my 3 when driving on ice last winter though, but a cheap compact would have a huge benefit for many throughout the world. They're both good, IMHO. There's no need to kill either.

 

[tstafford]

Buy a Taycan?

Taycan is more like an electric Panamera. Too big for me. The upcoming Boxster electric may be interesting. However Porsche's refusal to adopt one pedal is annoying.

 

[mborkow]

Taycan is more like an electric Panamera. Too big for me. The upcoming Boxster electric may be interesting. However Porsche's refusal to adopt one pedal is annoying.

I loved both my Porsches and an EV 718 might be hard to resist at around 80k.

 

[seenhear]

I do wish I had those thrusters on my 3 when driving on ice last winter though,

I have no idea why you think rocket thrusters would be beneficial for ice or hydroplaning. What's your background in physics?

 

[Earl]

I have no idea why you think rocket thrusters would be beneficial for ice or hydroplaning. What's your background in physics?

My background is sufficient in education and experience. Thrusters can provide thrust vectors that are independent of or increasing traction with the road depending on what direction they point. Ice and hydroplaning are a problem because the car loses traction with the road, hence you lose directional control.
That doesn't, of course, mean that Tesla is designing their thrusters to handle loss of traction with the road but what they are developing might very well be helpful if it reacts quickly enough.

 

[Darmie]

BYD's Yangwang reveals U9 electric supercar

BYD's new luxury spin-off brand Yangwang has revealed a surprise electric supercar that can do the 0-100km/h sprint in a claimed two seconds.

www.carexpert.com.au

Really, at this point, why bother with Roadster 20xx? It's almost comical.

... and this will be available in the States when?

 

[Darmie]

I loved both my Porsches and an EV 718 might be hard to resist at around 80k.

The MX5 has always been my kryptonite but I thought it was comical they are comparing it to being a level above the benchmark of Porsche's 718. Now if Mazda ever came out with great stats on an EV roaster, I'm all in.

 

[mborkow]

The MX5 has always been my kryptonite but I thought it was comical they are comparing it to being a level above the benchmark of Porsche's 718. Now if Mazda ever came out with great stats on an EV roaster, I'm all in.

I bought a Miata when I first moved to California; I wanted a Honda S2000 but it was just a little out of my reach. Miatas are great (and amazing value) but comparing them to Porsches is silly. I went from the Miata to a 911; there’s really no comparison.

 

[tangible1]

My background is sufficient in education and experience. Thrusters can provide thrust vectors that are independent of or increasing traction with the road depending on what direction they point. Ice and hydroplaning are a problem because the car loses traction with the road, hence you lose directional control.
That doesn't, of course, mean that Tesla is designing their thrusters to handle loss of traction with the road but what they are developing might very well be helpful if it reacts quickly enough.

and how do the thrusters manage to vector their thrust properly? how do they understand the intended direction of travel? integration to the navigation system?
nah, this is a half baked conjecture.

 

[seenhear]

and how do the thrusters manage to vector their thrust properly? how do they understand the intended direction of travel? integration to the navigation system?
nah, this is a half baked conjecture.

It's all plausible, but IMO the amount of thrust required to be meaningfully helpful in an emergency loss of traction situation (e.g. the ice/hydroplaning situation that @Earl described) is most likely way beyond what the thrusters will be able to provide. I haven't taken the time to do the math yet though. But just given the basics claimed so far (0-60 time going from ~2 seconds to ~1.1 seconds for a 4500lb car) it seems unlikely there'd be enough thrust to provide useful control in a zero friction situation.

Elon did state that the concept will include 10 thrusters positioned around the vehicle. That might be 3 in front to impart a braking force, 3 in back to impart a (forward) acceleration force, and one at each corner (pointing outward from the car probably???) to impart azimuth rotational moments.

One could envision that the activation of each individual rocket could be software implemented to be seamlessly synchronized with steering and braking inputs from the driver's controls (wheel/yoke and brake/accelerator pedals).

Again though, I do not think the proposed SpaceX package would have enough thrust and control authority to meaningfully help maneuver the vehicle in a zero/minimal traction situation. Not to mention the fact that the dynamics of the vehicle would be totally foreign to the typical driver who is used to friction/traction controls (i.e. tires on a dry road). It takes well-trained military pilots a long time to adjust to and learn how to control a space craft with thruster vectoring. There would need to be a lot of software implemented to make it remotely intuitive (and thus useful) to a typical automobile driver.

 

[tangible1]

It's all plausible, but IMO the amount of thrust required to be meaningfully helpful in an emergency loss of traction situation (e.g. the ice/hydroplaning situation that @Earl described) is most likely way beyond what the thrusters will be able to provide. I haven't taken the time to do the math yet though. But just given the basics claimed so far (0-60 time going from ~2 seconds to ~1.1 seconds for a 4500lb car) it seems unlikely there'd be enough thrust to provide useful control in a zero friction situation.

Elon did state that the concept will include 10 thrusters positioned around the vehicle. That might be 3 in front to impart a braking force, 3 in back to impart a (forward) acceleration force, and one at each corner (pointing outward from the car probably???) to impart azimuth rotational moments.

One could envision that the activation of each individual rocket could be software implemented to be seamlessly synchronized with steering and braking inputs from the driver's controls (wheel/yoke and brake/accelerator pedals).

Again though, I do not think the proposed SpaceX package would have enough thrust and control authority to meaningfully help maneuver the vehicle in a zero/minimal traction situation. Not to mention the fact that the dynamics of the vehicle would be totally foreign to the typical driver who is used to friction/traction controls (i.e. tires on a dry road). It takes well-trained military pilots a long time to adjust to and learn how to control a space craft with thruster vectoring. There would need to be a lot of software implemented to make it remotely intuitive (and thus useful) to a typical automobile driver.

even in a zero friction (ie no traction) environment, changing the inertial direction of a 4500lb vehicle going XXX mph..........requires a lot of energy.
of course it can be done, but as a practical engineering exercise the OP's conjecture is far fetched.
I see the thrusters as, best case, little more than acceleration/deceleration enhancements, certainly not directional change elements.

 

[kavyboy]

I always assumed the thrust would be down, to prevent slipping when accelerating. Any road debris would likely turned into dangerous projectiles. Lateral thrusters would dangerous to anything nearby, and wouldn't be strong enough to actually displace the car.
In reality, I doubt that such a thing is anything but a dream.

 

[Ben W]

[…] Not to mention the fact that the dynamics of the vehicle would be totally foreign to the typical driver who is used to friction/traction controls (i.e. tires on a dry road). It takes well-trained military pilots a long time to adjust to and learn how to control a space craft with thruster vectoring. There would need to be a lot of software implemented to make it remotely intuitive (and thus useful) to a typical automobile driver.

I imagine they would implement it to make the vehicle dynamics precisely mimic a very-high-grip tire on a dry track surface, even when the road is wet. If they could use the thrusters to e.g. simulate tires with 1.5 g lateral grip, that could be intuitive enough for high-performance track use. (And 1.0 g lateral grip for real-world driving on wet surfaces, perhaps with a warning chime when the thrusters are in use, though I imagine they may be VERY loud all by themselves!)

 

[seenhear]

I mean, all this assumes the thrusters are a viable thing in the first place. I'll honestly be very surprised if Tesla and SpaceX engineers have come up with a viable, safe (key point there) way to store the claimed 10,000 psi (what Elon claimed on the Joe Rogan podcast). I also wonder what kind of compressor Elon thinks he or his team are going to invent that can compress 25-30 lb of air to 10,000 psi in a reasonable amount of time without adding several hundred pounds to the vehicle.

But to go back to safety. SpaceX has been doing a great job with their rockets. But they are not to the level of safety that cars need to be. Not even within an order of magnitude. I for one don't want a 10 kpsi pressure vessel in the back seat of my car. Instant death if that fails.

 

[seenhear]

I always assumed the thrust would be down, to prevent slipping when accelerating. Any road debris would likely turned into dangerous projectiles. Lateral thrusters would dangerous to anything nearby, and wouldn't be strong enough to actually displace the car.
In reality, I doubt that such a thing is anything but a dream.

Really, the most optimal direction to face the thrusters if using them for emergency control enhancement, is opposite the direction the car is sliding (again assuming sliding on ice or water and needing to regain control ASAP).

A massive instantaneous impulse aimed opposite the vehicle's current velocity vector, would not only slow progress toward whatever hazard lies ahead, but immediately result in regained traction and thus regained control with steering and brakes via the tires.

Again though, this is all a pipe dream, IMO. There's no way they are getting the necessary volume of gas into a 10,000 psi chamber, safely, and efficiently. I'll have to take some time and run the numbers, but this just doesn't make sense on the face of it.

 

[tangible1]

Really, the most optimal direction to face the thrusters if using them for emergency control enhancement, is opposite the direction the car is sliding (again assuming sliding on ice or water and needing to regain control ASAP).

A massive instantaneous impulse aimed opposite the vehicle's current velocity vector, would not only slow progress toward whatever hazard lies ahead, but immediately result in regained traction and thus regained control with steering and brakes via the tires.

Again though, this is all a pipe dream, IMO. There's no way they are getting the necessary volume of gas into a 10,000 psi chamber, safely, and efficiently. I'll have to take some time and run the numbers, but this just doesn't make sense on the face of it.

we be deep on this one.
suffice it to say "it's Elon, let it go"

 

[Earl]

and how do the thrusters manage to vector their thrust properly?

inertial sensors, of course.

how do they understand the intended direction of travel?

Do I really have to answer this? Toward the front of the car, aligned with the road, on the vector before yaw began, of course.
How do you think they know to activate lane-departure warnings, active yaw control, etc?

this is a half baked conjecture.

Yep, but now there are smart people (and others) now discussing it

 

[Earl]

changing the inertial direction of a 4500lb vehicle going XXX mph..........requires a lot of energy.

When you hit ice, the most important thing and initial challenge is to keep the vehicle pointed forward. Today, counter-steering is the only means available. It has worked for me all times but one (car flipped ends and I jumped a ditch - backward. Then drove back to road). You don't actually need to affect the inertial direction, only the point of the car and keep it basically pointing in the way directed by the wheel.

 

[Earl]

I always assumed the thrust would be down, to prevent slipping when accelerating. Any road debris would likely turned into dangerous projectiles. Lateral thrusters would dangerous to anything nearby, and wouldn't be strong enough to actually displace the car.

My half-baked idea is also that lateral thrust would be a problem. You'd survive the ice but blow the poor guy beside you completely off the road. However, down thrust, possibly at ~45 degree angle would increase road traction while still having a lateral component that might help with yaw control.

we be deep on this one.
suffice it to say "it's Elon, let it go"

Why let it go? You have a $250K supercar to test it all out on.

 

[Earl]

it seems unlikely there'd be enough thrust to provide useful control in a zero friction situation.

Yep, if the plan is to just to provide semi-static downthrust when launching or entering a curve then the thrusters might not respond fast enough to control slipping on ice.

Elon did state that the concept will include 10 thrusters positioned around the vehicle. That might be 3 in front to impart a braking force, 3 in back to impart a (forward) acceleration force, and one at each corner (pointing outward from the car probably???) to impart azimuth rotational moments.

He also said it might be able to fly - that implies there may be upforce that exceeds the car's weight, somewhere but I don't see any value in that. Clearly, there was a lot of Elon conjecture, not proven concepts. I don't know that any rear thrusters would be needed for acceleration, downforce should be fine for that. It would seem that down thrusters at an angle, at the corners would provide enough traction for the wheels to do the acceleration while also enabling yaw control. Maybe they'd be gimballed to vector the thrust back and down for acceleration and sideways or forward and down while driving?

Not to mention the fact that the dynamics of the vehicle would be totally foreign to the typical driver who is used to friction/traction controls (i.e. tires on a dry road). It takes well-trained military pilots a long time to adjust to and learn how to control a space craft with thruster vectoring. There would need to be a lot of software implemented to make it remotely intuitive (and thus useful) to a typical automobile driver.

Yep, it would have to be automated and tuned very carefully in order to be usable.
Probably crazy but that's ok in my book.