Author Topic: Capability of SpaceX cold gas thrusters in the Roadster 2  (Read 44023 times)

Offline cscott

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Re: Capability of SpaceX cold gas thrusters in the Roadster 2
« Reply #80 on: 06/15/2018 04:46 pm »
Air bags do require that you stop driving after they are used.

Offline Welsh Dragon

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Re: Capability of SpaceX cold gas thrusters in the Roadster 2
« Reply #81 on: 06/15/2018 05:10 pm »
Only on NSF would we get four pages of discussion over something that is clearly a joke. No jurisdiction would ever allow this.

https://en.wikipedia.org/wiki/Jet_car So this shouldnt exist ?

Many jet cars on the public road around where you live?

Offline mme

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Re: Capability of SpaceX cold gas thrusters in the Roadster 2
« Reply #82 on: 06/15/2018 05:14 pm »
Only on NSF would we get four pages of discussion over something that is clearly a joke. No jurisdiction would ever allow this.
See: Space Thruster Technology for Motorcycles To Avoid Low Side Crash!

He starting the Boring Company funded by selling hats and not-a-flamethrowers, used his roadster as a mass simulator and has convinced multiple municipalities to let him start digging tunnels under their cities.  I've decided to take a wait and see attitude about everything he says. (After my initial, "that's clearly a joke" reaction to everything he says.) :)
Space is not Highlander.  There can, and will, be more than one.

Offline QuantumG

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Re: Capability of SpaceX cold gas thrusters in the Roadster 2
« Reply #83 on: 06/16/2018 03:20 am »
Only on NSF would we get four pages of discussion over something that is clearly a joke. No jurisdiction would ever allow this.

I'll say it one more time: this options package is for the track, not the road.
« Last Edit: 06/16/2018 03:20 am by QuantumG »
Human spaceflight is basically just LARPing now.

Offline docmordrid

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Re: Capability of SpaceX cold gas thrusters in the Roadster 2
« Reply #84 on: 06/16/2018 03:47 am »
>
I'll say it one more time: this options package is for the track, not the road.

Which would likely cause some rules committee to create an updated "Chaparral 2J* Rule."

* Can-Am car which created massive downforce using two vacuum fans. Banned after one season.
« Last Edit: 06/16/2018 03:48 am by docmordrid »
DM

Offline QuantumG

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Re: Capability of SpaceX cold gas thrusters in the Roadster 2
« Reply #85 on: 06/16/2018 03:58 am »
>
I'll say it one more time: this options package is for the track, not the road.

Which would likely cause some rules committee to create an updated "Chaparral 2J* Rule."

* Can-Am car which created massive downforce using two vacuum fans. Banned after one season.

Who said anything about competitive racing?

Are people really not aware how rich tech-bros spend their money? They buy fancy cars. They put them in garages. They tow them to the track. They drive around in circles. They tow them back to the garage. It's much like owning a horse - yes, some people race them, but most people just keep them so they can go riding.

Human spaceflight is basically just LARPing now.

Offline Ludus

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Re: Capability of SpaceX cold gas thrusters in the Roadster 2
« Reply #86 on: 06/16/2018 04:05 am »
>
I'll say it one more time: this options package is for the track, not the road.

Which would likely cause some rules committee to create an updated "Chaparral 2J* Rule."

* Can-Am car which created massive downforce using two vacuum fans. Banned after one season.

Who said anything about competitive racing?

Are people really not aware how rich tech-bros spend their money? They buy fancy cars. They put them in garages. They tow them to the track. They drive around in circles. They tow them back to the garage. It's much like owning a horse - yes, some people race them, but most people just keep them so they can go riding.

https://m1concourse.com/private-garages/

There are car condos. Like a place to stable your car at a track.

Offline docmordrid

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Re: Capability of SpaceX cold gas thrusters in the Roadster 2
« Reply #87 on: 06/16/2018 04:08 am »
>
I'll say it one more time: this options package is for the track, not the road.

Which would likely cause some rules committee to create an updated "Chaparral 2J* Rule."

* Can-Am car which created massive downforce using two vacuum fans. Banned after one season.

Who said anything about competitive racing?

Are people really not aware how rich tech-bros spend their money?
>

I was thinking about a derivation of the Electric GT (EGT) series Model S will be in.
« Last Edit: 06/16/2018 04:08 am by docmordrid »
DM

Offline intrepidpursuit

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Re: Capability of SpaceX cold gas thrusters in the Roadster 2
« Reply #88 on: 06/17/2018 01:24 am »
The idea that bursts of air coming out of nozzles around a car going at high speed is a safety concern is ridiculous. The air pressure will diffuse extremely quickly and nothing should be super close to a car at high speed anyway. Some performance cars blow fire out of their exhaust, they release pressure from blow off valves, have tanks of compressed nitrous oxide, they have giant wings, etc. We are talking about a car that can accelerate at over 1G and go 250+ mph and we are worried about puffs of air? Every KIA Soul has capabilities that would be dangerous to use on neighborhood roads, that doesn't make them illegal to use there.

If you hate lavish sports cars that is fine, but compressed air thrusters are a really silly place to draw a line.


Offline Welsh Dragon

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Re: Capability of SpaceX cold gas thrusters in the Roadster 2
« Reply #90 on: 06/17/2018 02:34 pm »
The idea that bursts of air coming out of nozzles around a car going at high speed is a safety concern is ridiculous. The air pressure will diffuse extremely quickly and nothing should be super close to a car at high speed anyway. Some performance cars blow fire out of their exhaust, they release pressure from blow off valves, have tanks of compressed nitrous oxide, they have giant wings, etc. We are talking about a car that can accelerate at over 1G and go 250+ mph and we are worried about puffs of air? Every KIA Soul has capabilities that would be dangerous to use on neighborhood roads, that doesn't make them illegal to use there.

If you hate lavish sports cars that is fine, but compressed air thrusters are a really silly place to draw a line.
You think the worry might be more about high pressure tanks?

Offline meekGee

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Re: Capability of SpaceX cold gas thrusters in the Roadster 2
« Reply #91 on: 06/17/2018 03:37 pm »
The idea that bursts of air coming out of nozzles around a car going at high speed is a safety concern is ridiculous. The air pressure will diffuse extremely quickly and nothing should be super close to a car at high speed anyway. Some performance cars blow fire out of their exhaust, they release pressure from blow off valves, have tanks of compressed nitrous oxide, they have giant wings, etc. We are talking about a car that can accelerate at over 1G and go 250+ mph and we are worried about puffs of air? Every KIA Soul has capabilities that would be dangerous to use on neighborhood roads, that doesn't make them illegal to use there.

If you hate lavish sports cars that is fine, but compressed air thrusters are a really silly place to draw a line.
You think the worry might be more about high pressure tanks?
CNG cars already have them, and that comoressed flammables gas.  Air will be even safer.

Too bad they can't compress CO2...  Damn exhaustless electric motors.

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Offline intrepidpursuit

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Re: Capability of SpaceX cold gas thrusters in the Roadster 2
« Reply #92 on: 06/17/2018 07:26 pm »
The idea that bursts of air coming out of nozzles around a car going at high speed is a safety concern is ridiculous. The air pressure will diffuse extremely quickly and nothing should be super close to a car at high speed anyway. Some performance cars blow fire out of their exhaust, they release pressure from blow off valves, have tanks of compressed nitrous oxide, they have giant wings, etc. We are talking about a car that can accelerate at over 1G and go 250+ mph and we are worried about puffs of air? Every KIA Soul has capabilities that would be dangerous to use on neighborhood roads, that doesn't make them illegal to use there.

If you hate lavish sports cars that is fine, but compressed air thrusters are a really silly place to draw a line.
You think the worry might be more about high pressure tanks?

I already mentioned nitrous oxide. That is extremely flammable and stored at 750psi in cars all the time, and you can't safely vent it. The air pressure tanks can just have a relief valve tied to an inertial switch that bleeds the air quickly and safely if something goes wrong, just like fuel cut-off valves in gas cars.

Offline unkulunkulu

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Re: Capability of SpaceX cold gas thrusters in the Roadster 2
« Reply #93 on: 06/17/2018 09:46 pm »
I think the thrusters as more of adaptive aerodynamics than providing thrust to the car.  Isp is really too low for the latter.  Something along the lines of the patent linked below.

https://patents.google.com/patent/US5908217A/en

Effectively, by controlling drag, they could control the amount of downforce on the car, and by introducing drag at an edge or corner they could adjust the pitch and yaw.  Also, since they could also reduce down force at speed it could also be used to do a controlled launch of a moving roadster in the air by turning it into a lifting body. 

Somehow I think some SpaceX engineer just plugged a roadster model into their sim for stage 1 reentry and found out that they could guide it with the CGTs just the same.   

Offline meekGee

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Re: Capability of SpaceX cold gas thrusters in the Roadster 2
« Reply #94 on: 06/17/2018 09:57 pm »
>
I'll say it one more time: this options package is for the track, not the road.

Which would likely cause some rules committee to create an updated "Chaparral 2J* Rule."

* Can-Am car which created massive downforce using two vacuum fans. Banned after one season.

Who said anything about competitive racing?

Are people really not aware how rich tech-bros spend their money? They buy fancy cars. They put them in garages. They tow them to the track. They drive around in circles. They tow them back to the garage. It's much like owning a horse - yes, some people race them, but most people just keep them so they can go riding.

QG - most road accidents happen with warning, but not enough warning for the car and driver to react in time.

Computers can help with detecting an impending collision or loss of control, but even computers can't make up for limited tire traction, especially if the road is wet or icy or oily.

I don't think it's a hard sell to the NTSB to have this system considered as an active safety system, and just cap the maximum speed it can achieve while on a public road.

Also, because of noise issues, maybe inhibit the forward thruster under 55 MPH while on public roads.
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Offline JamesH65

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Re: Capability of SpaceX cold gas thrusters in the Roadster 2
« Reply #95 on: 06/18/2018 11:41 am »
IMO braking and cornering are the main benefits. Good braking means you can remain faster for longer before entering a turn. Cornering means you can stay faster while inside the turn.

On public roads this is a huge safety feature. Braking or performing an aggrrssive avoidance maneuver on an icy road without losing traction?  Handling an unexpected slippery patch in mid turn?  Braking on a dime when a prdestrian pops into your lane?

Those are life savers. I don't see why this would be disallowed, especially if auto-controlled like automatic stability control.


The problem is that if the driver knows that the thrusters will save him on unexpected situations, he will start taking more risks. And then he takes two risks in short time frame and the system has not had time to recharge in between.

The system should be such that if it activates on normal traffic, it automatically calls the police, gives the driver ticket for reckless driving, and allows continuing driving only after it has rechaged itself ;)

No, not really. 99.9% of drivers never even get remotely close to the actual performance levels of their cars round corners (anyone can drive fast in a straight line). If I take people out in a standard car and use a heavy right foot, they generally cannot believe how much faster the cars are capable of going around the bends. (As a citation, I used to race karts then spend two years racing cars in the UK, and I don't do it very often on the roads!)


Offline Cologan

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Re: Capability of SpaceX cold gas thrusters in the Roadster 2
« Reply #96 on: 06/18/2018 12:37 pm »
Only on NSF would we get four pages of discussion over something that is clearly a joke. No jurisdiction would ever allow this.

https://en.wikipedia.org/wiki/Jet_car So this shouldnt exist ?

Many jet cars on the public road around where you live?

Please read my sentence directly below the quote :)

EDIT: You can see enough crazy contraptions on tracks these days, is there any point in discussing whether or not it should be street legal ? as far as i remember this threads title is about the "Capability" of such system, lets focus on that.
« Last Edit: 06/18/2018 12:45 pm by Cologan »

Offline Ludus

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Re: Capability of SpaceX cold gas thrusters in the Roadster 2
« Reply #97 on: 06/19/2018 04:02 am »
Only on NSF would we get four pages of discussion over something that is clearly a joke. No jurisdiction would ever allow this.

https://en.wikipedia.org/wiki/Jet_car So this shouldnt exist ?

Many jet cars on the public road around where you live?

Please read my sentence directly below the quote :)

EDIT: You can see enough crazy contraptions on tracks these days, is there any point in discussing whether or not it should be street legal ? as far as i remember this threads title is about the "Capability" of such system, lets focus on that.

They can be related questions. If the system can for example significantly reduce stopping distance in an emergency it will get more consideration as an active safety system.


Offline hkultala

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Re: Capability of SpaceX cold gas thrusters in the Roadster 2
« Reply #98 on: 06/19/2018 04:50 am »

No, not really. 99.9% of drivers never even get remotely close to the actual performance levels of their cars round corners (anyone can drive fast in a straight line).

Please try to understand the difference between 75% and 99.9%. Your "99.9%" is actually about 75%.

Also, there are things like ice and water on the real roads in the real world.
« Last Edit: 06/19/2018 04:50 am by hkultala »

Offline JamesH65

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Re: Capability of SpaceX cold gas thrusters in the Roadster 2
« Reply #99 on: 06/19/2018 11:32 am »

No, not really. 99.9% of drivers never even get remotely close to the actual performance levels of their cars round corners (anyone can drive fast in a straight line).

Please try to understand the difference between 75% and 99.9%. Your "99.9%" is actually about 75%.

Also, there are things like ice and water on the real roads in the real world.

75%? No way. Absolutely no way the 25% of drivers are capable of driving (safely) at the limits of whatever car they are driving.

Of course, quite a few exceed the limits, which is why they crash. But the number of people who drives safely AT the limits is few.

Ice/rain has nothing to do with it.

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