TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker and becoming a Supporting Member. For more info: Support TMC
  1. TMC is currently READ ONLY.
    Click here for more info.

Speculative Aerodynamic Model of Thrusters

Discussion in 'Roadster 2022' started by MESM, Jul 20, 2018.

?

Is this how Elon does it?

Poll closed Aug 4, 2018.
  1. Impossible/ Ridiculous

    0 vote(s)
    0.0%
  2. Your explanation is terrible

    0 vote(s)
    0.0%
  3. Interesting but wrong

    15.4%
  4. Interesting

    69.2%
  5. Yes

    15.4%
  1. MESM

    MESM Member

    Joined:
    Jul 5, 2018
    Messages:
    24
    Location:
    Cheltenham
    You are right - Elon might be using actual thrusters that can push and corner a two tonne car but I also think that you are right to guess that that solution might not be road legal.

    My bet is still for suction using an air curtain rather than small directed nozzles. In the last month or two I redid the estimates and I got about 400 mph for the speed of the air in the curtain. Pebbles that were thrown up would not break your skin (surprisingly).

    (PS I have assumed 10,000 psi because that was a figure that Elon used in an interview. My earlier calculations used 5,000 psi but it turned out that 'ordinary'/typical was not good enough for SpaceX!)
     
  2. AirKuhl

    AirKuhl Member

    Joined:
    Dec 23, 2016
    Messages:
    42
    Location:
    SCruz Mtns CA and way north ID
    #42 AirKuhl, May 16, 2019
    Last edited: May 16, 2019
    Thank you Megan for digging into the science behind a fascinating topic. I just have 2 comments that may be useful.

    A rubber car tire on pavement has many forces involved besides friction, thus there is nothing magical about 1 G. Dragsters and F1 cars can break 3-6 G's during acceleration, braking and cornering. Note that early acceleration and late braking are too slow to involve aerodynamics.

    You may want to look into the Chaparrral 2J race car from 1970, which used active aerodynamics much like you describe in actual race conditions (quite effectively).
     
  3. MESM

    MESM Member

    Joined:
    Jul 5, 2018
    Messages:
    24
    Location:
    Cheltenham
    @AirKuhl Thanks for that. I am hoping that he will announce the car soon.
     
  4. Brando

    Brando Active Member

    Joined:
    Sep 27, 2016
    Messages:
    2,841
    Location:
    Bainbridge Island, WA
    #44 Brando, Jun 28, 2020
    Last edited: Jun 28, 2020
    • Informative x 1
  5. Brando

    Brando Active Member

    Joined:
    Sep 27, 2016
    Messages:
    2,841
    Location:
    Bainbridge Island, WA
    side note: Drag Race - Thruster only need to operate for about 1 second, maybe 2 seconds to improve 0-60 mph.
    Obvious, right?
     
  6. MESM

    MESM Member

    Joined:
    Jul 5, 2018
    Messages:
    24
    Location:
    Cheltenham
    It is better than 1.8 to 60 according to the test driver. In an early model I experimented with Bernoulli for 0 to 30 because in that regime you are friction limited - at (some) higher speed you will be traction limited.

    If you still like the pure thrust story then a similar argument could be applied.

    But of course Elon might choose to use the thrusters for longer to go faster anyway. Those tanks have phenomenal energy content

    (Finally there is a detail about the Bernoulli solution - because the gas flow rates are lower you have time to warm the exhaust gas - and that would affect your timing choices as well.

    It sounds as though we will find out soon enough!
     
  7. MESM

    MESM Member

    Joined:
    Jul 5, 2018
    Messages:
    24
    Location:
    Cheltenham
    If you are interested in this stuff there is a really good Sandy Munro interview with NowYouKnow here .
     
    • Informative x 1

Share This Page

  • About Us

    Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.
  • Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


    SUPPORT TMC