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Thread: Aerodynamics of the new Mirage (0.27-0.31 drag coefficient varies with options)

  1. #91
    Senior Member Mitz's Avatar
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    This is for trial ..

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    but I still want the Airtabs ..



  2. #92
    Senior Member Cani Lupine's Avatar
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    On a sidenote, did that aftermarket antenna improve radio reception? I just can't get the radio to come in very clear on mine.

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage DE 1.2 manual: 49.2 mpg (US) ... 20.9 km/L ... 4.8 L/100 km ... 59.1 mpg (Imp)


  3. #93
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    Quote Originally Posted by Cani Lupine View Post
    It's better to just seal the gaps, VGs would add some drag, which ends up with a lower net gain. The other reason is crosswind, you'd end up with a worse Cd.

    Overall, this gets into the "splitting hairs" category.
    If it were for the panel gaps only, then yeah, not worth it.

    However the VGs had shown to improve efficiency of spoilers, so without tests it is hard to say if they will improve or hurt our car.

    If you are interested in subject, there are a couple links:
    http://ecomodder.com/forum/showthrea...ors-32641.html
    http://ecomodder.com/forum/showthrea...car-33237.html
    https://www.researchgate.net/publica...Passenger_Cars

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 46.4 mpg (US) ... 19.7 km/L ... 5.1 L/100 km ... 55.7 mpg (Imp)


  4. #94
    Senior Member Cani Lupine's Avatar
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    Though comparing our roofline to the rear end of a Lancer is definitely apples to oranges, considering the Evo wing/VG study is looking at air flowing over and under the wing, and hatchbacks don't have trunks.

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        click to view fuel log View my fuel log 2014 Mirage DE 1.2 manual: 49.2 mpg (US) ... 20.9 km/L ... 4.8 L/100 km ... 59.1 mpg (Imp)


  5. #95
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    Quote Originally Posted by Cani Lupine View Post
    Though comparing our roofline to the rear end of a Lancer is definitely apples to oranges, considering the Evo wing/VG study is looking at air flowing over and under the wing, and hatchbacks don't have trunks.
    Agree hatchback is more similar to tractor trailer or wagon. Read this:
    http://s89686473.onlinehome.us/airtabs-test.html

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 46.4 mpg (US) ... 19.7 km/L ... 5.1 L/100 km ... 55.7 mpg (Imp)


  6. The Following User Says Thank You to cyclopathic For This Useful Post:

    Mitz (12-23-2015)

  7. #96
    Senior Member Mitz's Avatar
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    Quote Originally Posted by cyclopathic View Post
    Agree hatchback is more similar to tractor trailer or wagon. Read this:
    http://s89686473.onlinehome.us/airtabs-test.html
    A good read

  8. #97
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    Not sure if this has been discussed before. One of the aerodynamic quirks of Mirage is the A-pillar placement. It looks like car is the widest at that level at A-pillar.

    This pushes air over the roof and reduces side flow. Better aerodynamics, less wind noise with windows up and down.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 46.4 mpg (US) ... 19.7 km/L ... 5.1 L/100 km ... 55.7 mpg (Imp)


  9. #98
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    Quote Originally Posted by MetroMPG View Post
    Optimal VG placement depends on the depth of the boundary layer, height & angle of the VG's. You place them close to the point of separation, but far enough ahead of it that the top of the VG can mix the faster flowing air in the upper part of the layer with the slower bottom layer. You've probably seen this: Mitsu wrote an entire research paper on the size & placement of VG's on the EVO's roof...

    http://mirageforum.com/downloads/16E_03.pdf

    You can see why getting it right is hard to guess at.

    ---

    If flow is actually separated on the 2012-2015 Mirage's rear spoiler, then VG's might help a tiny amount... if they're placed right.

    Changing the angle of the spoiler itself would be better since it avoids the drag penalty of generating the vortices in the first place, which are really just a band-aid.

    I'd love to see a tuft test of the '12-15 spoiler.
    Bringing this back for discussion (This is actually x-post from Prius C bad highway MPG thread at ecomodder):
    =======================================
    So got to travel on the same road in very similar conditions (load, temperature, wind, etc). Once again using cruise control to take driver out of consideration.

    Computer calculated MPG was 41.4 vs 38.7 last time, this is average over almost an hour (had to abandon test after ~50mi as we ran into construction zone with lower speed limit). 7% improvement.

    Difference? A set of EVO-style vortex generators installed alone the roof trailing edge.

    I am building the underbelly panels when it warms up.
    ==================================

    Prius C computer collects the MPG data on monthly basis, and the data collected in past 4 month seem to confirm the trend, though they are too imprecise to use in calculations. Since car gets ~2,300-3,000mi a month, this is result of ~11k worth of miles.

    Also it looks like my suspicion is correct, and Prius C aerodynamically slightly worse than Mirage, despite both rated at 0.28 Cd.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 46.4 mpg (US) ... 19.7 km/L ... 5.1 L/100 km ... 55.7 mpg (Imp)


  10. #99
    Moderator Eggman's Avatar
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    cyclopathic, are wind speed and direction being noted in your data?

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 49.6 mpg (US) ... 21.1 km/L ... 4.7 L/100 km ... 59.5 mpg (Imp)


  11. #100
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    Quote Originally Posted by Eggman View Post
    cyclopathic, are wind speed and direction being noted in your data?
    That section of interstate is forested no wind to speak of, and it was both during night time when wind is blowing the last. Also both times winter gas E10 now not sure about previous time.


        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 46.4 mpg (US) ... 19.7 km/L ... 5.1 L/100 km ... 55.7 mpg (Imp)


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