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Thoughts on the new Roadster’s “over 250mph” top speed claim by Elon

Discussion in 'Roadster 2022' started by ecarfan, Nov 17, 2017.

  1. Krash

    Krash Data Technician

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    Can't you use the compressed air for cooling as well? I mean if you could pickup any heat energy from say a heat pump you just get extra gas expansion, right?
     
  2. mongo

    mongo Well-Known Member

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    Only if you cooled the compressed air to begin with. Even then, without a phase change, it's way less efficient than adding additional AC compressor capacity.
     
  3. Krash

    Krash Data Technician

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    #83 Krash, Jul 18, 2018
    Last edited: Jul 18, 2018
    But the compressed air is already cooler than the heat coming out of the motor. I can see how the expansion benefit might be outweighed by the weight of the heat pump and any mechanism for transfer from solid to gas if the transfer rate is low.

    Speaking of phase change, at current COPV pressures do you still have to cool air below -200C to make it liquid? I realize a COPV is no vacuum container.
     
  4. mongo

    mongo Well-Known Member

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    If the tank of air is at ambient sure, but for freshly compressed air (active cooling), the temp rise of a 10:1 compression without heat removal is ~896 F Adiabatic process - Wikipedia
    Compressing and releasing the air without intermediate cooling provide hotter air due the work done.

    SpaceX runs sub-cooled liquid oxygen, the additional pressure is there for structural reasons. The COPVs hold helium to maintain tank pressure. I can't find a reference regarding pressure to liquefy air, for Nitrogen, the phase change charts stops at 100 atm (14,700 psi). It's likely not possible What pressure would Air Liquify - Ars Technica OpenForum
     
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  5. Krash

    Krash Data Technician

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    #85 Krash, Jul 18, 2018
    Last edited: Jul 18, 2018
    Looks like you can get room temperature liquid Nitrogen at 45,000 psi. Considering Space X COPVs may be 4500 psi we are closer than I would have expected.

    Pressure of sealed in liquid nitrogen
     
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  6. mongo

    mongo Well-Known Member

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    Interesting!
    So a 10 layer COPV could do it...
     
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  7. scaesare

    scaesare Well-Known Member

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    Incidentally, I hope the top speed is 256MPH.

    Because.. you know... binary.
     
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  8. Krash

    Krash Data Technician

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    #88 Krash, Jul 18, 2018
    Last edited: Jul 18, 2018
    I wonder if Tesla will try to adjust cabin temperatures by using the temperature difference in compressing and releasing air. Like internal combustion exhaust is used to heat.
     
  9. Krash

    Krash Data Technician

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    Anyone know the color frequency of maximum plaid?
     
  10. mongo

    mongo Well-Known Member

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    I hope the speed value is not a byte. Otherwise, if it goes above 255 you get....
    rollover....
     
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  11. ICUDoc

    ICUDoc Active Member

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    Known frequency of Maximum Plaid is just above visible light (UV spectrum): 2 to the power of 50 exactly.
    That's 1125899906842624 Hz, FYI.
     
  12. MESM

    MESM Member

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    I think that playground rides are limited to 2 or 2.5 g.

    I think that the SpaceX options put the car in that range for several seconds; I think that it is initially limited by grip and then later by maximum power)

    For example 2 g at 60 mph is ~ 1,000,000 Watts (assuming low losses) At zero mph power is ~ 0 Watts (ignoring losses heating etc).
     
  13. oneday

    oneday Active Member

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    Elon said at the hyper loop competition last week that he was putting cold gas thrusters on the SpaceX pod and expecting it to hit 350mph. He also mentioned he was going to test it in the new Boring tunnel, so perhaps not under vacuum.
     
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  14. aikisteve

    aikisteve Member

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    I'm betting more he wants to be the first production car to crack 300mph. Of course, there's only like 2 or 3 places in the world where you can actually do this. But then again, the Chiron also sells on numbers...
     
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  15. Brando

    Brando Active Member

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    450 Bugatti Veyrons have been made and sold. 300 coupés and 150 roadsters have been made, the last Veyron was an open-top Grand Sport Vitesse variant, called La Finale. The 450 Veyrons were sold for an average price of about 2.3 million euros ($2.6 million) each
    May 30, 2016

    450 x 2,600,000 = 1,170,000,000/50,000 = 23,400 model 3 at average price of $50,000
    ==============
    Bugatti have manufactured 450 Veyrons till date. There have been 270 Veyron 16.4 (the first variant), 30 Veyron 16.4 Super-Sport (the world record variant), and 150 Veyron Grand-Sports and Grand-Sport Vitesse's. The 450th Bugatti Veyron, Grand-Sport Vitesse La Finale, was unveiled at the 2015 Frankfurt Motor Show. Bugatti have now increased the number of Chiron's to 500, over a product cycle of around 8 years.

    500 (average price over 8 years?? how about $2,000,000?) = $1,000,000,000/50,000 = 20,000 model 3 at average price of $50,000

    You get the idea - put in your own numbers. The revolution has started, I think.:rolleyes:
     
  16. CarlK

    CarlK Active Member

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    it will not be limited by grip if power is provided by thrusters.
     
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  17. FlatSix911

    FlatSix911 Porsche 918 Hybrid

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    The Bugatti Veyron EB 16.4 is a mid-engined sports car, designed and developed in Germany by the Volkswagen Group... think Dieselgate :cool:

    Bugatti Veyron - Wikipedia
     
  18. RDoc

    RDoc S85D

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    Does anyone think this speed is going to be under its own power on level ground?

    Elon's personal Roadster has reached well over 8000 mph.
     
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  19. Ludalicious

    Ludalicious Active Member

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    I would like to know how they are going to get that torque to the ground. I mean my P100D leaves rubber all over the side of my car. It's just nasty. The torque rips the crap out of tires. wonder if the rims will have beedlocks on the inside to stop the tires from slipping.

    Here's a photo of the road rash my current tires leave. Just nasty 20180813_112003.jpg material. get it on all 4 corners too after hard launches.
     
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  20. Cosmacelf

    Cosmacelf Well-Known Member

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    I was about to say, but that is only true if your road is very straight, because good luck turning without grip. But then I remember that Elon was even envisioning the thrusters helping to turn the car.

    Heck, Elon, just make a fully rocket powered car. You know you want to :p
     

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