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The aerodynamic test "buck"

Discussion in 'Roadster' started by TEG, Aug 12, 2007.

  1. TEG

    TEG TMC Moderator

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    #1 TEG, Aug 12, 2007
    Last edited: Nov 20, 2007
    The aerodynamic test "buck"

    Along with "the Mule" (a drivable pre-prototype), Tesla build a clay model (to refine the body styling), and an aerodynamic "Buck" to go through the wind tunnel.

    These are pictures of "The Buck" at Tesla HQ:

    393801228_c4436f89fa.jpg
    397175385_6d99a6c67c.jpg
    393766369_ca88cd2662.jpg
     
  2. Martin

    Martin Tesla Founder

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    The black car in the background is not clay. It is a machined aerodynamic "buck" that was later used for some styling experiments. We still have that buck as a museum piece. We did build a clay model in the UK, and that model was indeed destroyed. Perhaps one day I will post pictures of its destruction :)
     
  3. vfx

    vfx Well-Known Member

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    "...clay model ...was indeed destroyed. Perhaps one day I will post pictures of its destruction."

    Would those be sold as cancellation proofs?
     
  4. TEG

    TEG TMC Moderator

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    #4 TEG, Oct 25, 2007
    Last edited: Oct 27, 2008
    Thanks, Martin...

    I updated the comment on the photo in this topic.

    Your MPG talk slides (page 62) do show a sledgehammer job on the (silver) clay model in Aug 2006.

    So it must be the "buck" ("museum piece") that showed up at Burning Man?
    1332823601_80896a6338.jpg
    1378444402_5f95927f77.jpg
    [​IMG]
     
  5. TEG

    TEG TMC Moderator

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    Perhaps this was the 'buck' before it got painted?
    [​IMG]
     
  6. TEG

    TEG TMC Moderator

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  7. doug

    doug Administrator / Head Moderator

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  8. TEG

    TEG TMC Moderator

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    From here: "The clay model... This was shipped form Norway after the wind tunnel tests. Normally the factory in Norway would break the model but the wise people at Tesla respected the future value that this historic model will have and shipped it to the US!"
     
  9. Cobos

    Cobos S60 owner since 2013

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    Why was the clay model ever in Norway ? Do we have any companies doing that kind of stuff?

    Cobos
     
  10. vfx

    vfx Well-Known Member

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    "we"?





    .
     
  11. TEG

    TEG TMC Moderator

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    As in him and all those other Norwegians...
     
  12. Cobos

    Cobos S60 owner since 2013

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    Yes, using we was maybe a bit presumptious, but I was refering to the collective Norwegian we :)

    Cobos
     
  13. vfx

    vfx Well-Known Member

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    So how would "we" know?
     
  14. Cobos

    Cobos S60 owner since 2013

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    I don't know :) I was just hoping someone had read or heard something?

    Cobos
     
  15. TEG

    TEG TMC Moderator

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    Nope, just the one reference on the Flickr photo.
    My guess is that there is/was a "buck factory" in Norway, and they did the aero testing at a wind tunnel in Europe (perhaps the MIRA one in the UK). Apparently the buck was shipped back to the USA as a "conversation piece" as (from what I can tell) it had already served its' purpose.
     
  16. vfx

    vfx Well-Known Member

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    :rolleyes::smile:
     
  17. Archaeopteryx

    Archaeopteryx New Member

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    Hmm... I've been using FLUENT 6.3 for a little while now, and I'm pretty familiar with the interface - It puzzles me that the above image has apparently been plotted as a graph of "Contours of Velocity Magnitude", when velocity magnitude graphs are used to describe fluid flow fields, rather than surface contours.

    You see, the following is a graph of the velocity magnitude contours of a fluid flow field around a rudimentary circuit board represented as a box attached to a plane; the colors you see are plotted on a plane slicing through the fluid, and are correspondent with the velocities of the channels of fluid flowing around the box:

    [​IMG]

    But the image you posted was apparently a graph of the velocity magnitude contours of the actual surface of the car, which makes no sense to me. Plotting the surface of a car according to its velocity would yield an image like this:

    [​IMG]

    Because it's not the surface that's moving [that has velocity], it's the fluid around the surface which does, and thus can be plotted. I don't see how the image you posted was a plot of the contours of velocity magnitude of the surface of the car itself, as it appears to be, and I WOULD PAY GOOD MONEY for someone to explain to me what's going on here.

    Seriously, if the aerodynamicist / computational fluid dynamicist of the Tesla Roadster does indeed participate in these forums, or can be reached via email or any other method, I would be extremely appreciative to ask him/her about this image.

    Doug, if you have any idea how I might be able to find out more about this image, or if you know how to reach maybe one of the technical directors of the Tesla team I would wash your dishes & shine your shoes for a month. :smile:
     
  18. doug

    doug Administrator / Head Moderator

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    #18 doug, Jan 7, 2009
    Last edited: Jan 7, 2009
    Ehh... my fluid dynamics is a bit rusty...
    I might be misunderstanding you, but I don't see why the velocity magnitude contours have to be restricted to a plane. Can't you plot them on an arbitrary 2D surface existing in 3 space? Yes, the surface of the car isn't moving, and classically the flow directly next to the surface is zero. But shouldn't you be able to define a new surface a small distance, say a few millimeters, from the skin of the car and then plot your contours there?

    At any rate, I don't know the guys at Tesla that work on this stuff. Your best bet would be to contact Fluent, since they should have aero experts able to support their software. Or perhaps even MIRA since they're the guys that likely produced the image.


    .
     
  19. malcolm

    malcolm Active Member

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    Doug's right.

    I think that if you do a plot of the true surface of the car then, as you would expect, the air in contact with the car body will be stationary and should be shown in blue.

    I think the image of the Tesla is made by calculating the air flow at a fixed distance above/away from the true surface of the vehicle. I think this is why the struts supporting the wing mirrors look a bit too chunky and why the windscreen wiper has been ignored. Presumably the aim is to try to keep the air moving as fast as possible over the vehicle.

    Since 30 m/s is about 108 km/hr or 68 mph does anyone know if the airflow over the wheels calculated with rotating or stationary wheels?
     
  20. doug

    doug Administrator / Head Moderator

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    Looks stationary.
     

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