May the DownForce be with you-(Lots of Reading but WORTH IT)

Discussion in 'The Garage' started by CrystalWhiteStallion, Nov 28, 2015.

  1. CrystalWhiteStallion

    CrystalWhiteStallion New Member

    Messages:
    27
    Likes Received:
    0
    Joined:
    Nov 27, 2015
    So here is the setup two 94-98 mustangs( excludes cobra) one is factory specification and the other is not. Now before I continue any further these numbers are based on a 100 % resistance free environment eliminating mechanical and natural limiting factors and i will be simplifying a majority of the information if you have any further questions don't be afraid to ask , now lets get down to the dirty stuff. Have any of you ever heard the statement "That wing/spoiler doesn't do anything" well i know i have and it is always so fun explaining why it is not a wing but that is for later. It is pretty obvious the sn95 mustang was not built in a wind tunnel however curvaceous and robust its hips and ass may look. But what kind of numbers does a sn95 put down in the aerodynamics category...? Well i'm glad you asked a base model 1994-1998 mustang w/spoiler puts down a whopping 300lbs of downforce across the platform of the vehicle with a slight increase in the front end due to the 54/46 weight ratios. But what does this mean i can just hop in my car and cruise at 55mph and assume i'm getting 300 extra pounds to keep me stuck to the road, well.... not really. After several tests and using Ford's specified top speed as one of the set data points i summarize that in order for a completely stock 1994-1998 mustang to generate 300lbs of downforce it has to travel at 150mph continuously while its ragtop counter part needed 157.2mph to generate this. Ya, i know :mad::cool: "my car isn't stock so it can hit 150mph easy and i have a chin splitter, a spoiler and a diffuser i made with super glue and crayons.", well i am proud of you and i hope you are killing corvettes in your dreams , but that isn't what this is about.:rolleyes: This is more about what the air does to our mustangs and how we can harness it and understand why our cars do what they do at certain speeds. If your still reading this congratulations you know more than all ADHD mustang owners out there. So on that bombshell lets take a look at what a stock mustang does at 55 and 150 mph. The image of the car may look bad but the numbers and dimensions of car are exact this is just a rough cut image on top of a single outline (easier to see) for all the older guys out there!


    This a mustang at 55mph provided 32.7lbs of downforce as you can see the red goes almost directly toward the ground as it swirls between the decklid and the bumper .The fuel tank cover is releasing air from underneath the car again in an almost vertical fashion as well. This creates a low pressure zone and exists in some form on every car. The real problem in this photo is where the green begins to form back pressure ie drag.

    [​IMG]


    Our 150mph provided 300lbs downforce Mustang looks slightly different as we can see a more fluid transition of the red of the back of the car and if you notice the red at the end has similar shape and angle to the rear spoiler! :shocked: And now the low pressure zone is in majority controlled by the green as it helps the red maintain its trajectory. We do see one small area on the rear glass where green escapes the vortex and all this is doing is attempting to fill all low pressure zones for red.


    [​IMG]


    And now we are going to check out my guinea pig and brave test subject for this demonstration. He has one of the baddest ragtops i have ever seen and is not afraid to test the limits of the sn-95s aerodynamic capabilities. Ferocious has generously donated dimensions and a picture of his car (all dimensions will we be retained to protect designs and individuality.) So as most of you know he has a front splitter and air dam extending toward the motor and yes size matters, front canards, rocker flashing, rocker winglets , rear diffuser , s281 rear spoiler. And finally the most defining piece of aero equipment on the vehicle a soft top.


    Ferocious traveling at 55mph generates a downforce poundage of 41lbs however his drag is slightly higher than a stock mustang. This test confirms that his mustang is able to not only send red over the car but it is significantly lowered to the boundary of drivability pushing green over the car. This picture as you may realize does look quite different toward the rear of the car and this has to do with the turbulence the mixing of red and green caused by excessive pressure on the ridged portion of the roof causing a chop effect. However the slip stream for his car is astounding as it already provides the proper trajectory off the rear of the car and almost meeting the derived prime value of greens tangent slope .
    (ITS DAMN NEAR PERFECT)..

    [​IMG]


    And finally the number you have all been waiting for Ferocious' ragtop Mustang at 150mph produces an incredible 402.397lbs of downforce. As you can see the low pressure zone is being diffused rapidly enough that it is effectively reducing drag and outperforming the stock mustang by 12.6% in the anti lift test. If you have ever heard someone say or have gone over 150 mph it is commonly referred to as spooky floating feeling almost as if the front tires are about to come off the ground . But momma didn't raise no quitter so you don't brake until you see jesus type of feelings. Well in his car you can go even faster before this starts happening and this is where i get to explain my wing/spoiler comment from earlier at 150mph a wing on the rear of his car would pull the front tires off of the ground , a spoiler makes the front of the car weigh 400lbs more. Anyways here's the second picture


    [​IMG]


    In summary you can now effectively and confidently make snide remarks to people who refer to that thing on your trunk as a wing that's there just for looks and until you get up to 150mph it might as well but they don't have to know that. ;);) I hope you all enjoyed and if you have any questions feel free to message away! And a big thank you to Ferocious for being a team player and letting me do this analysis!!!:headbang::headbang::slowclap::slowclap ::wave::wave::thumbsup: One last thing ( i do not condone or support exceeding designated speeds on public roads if you want to run it hard and test the science behind aerodynamics take it to the track guys).
     
  2. ttocs

    ttocs Legend

    Messages:
    25,419
    Likes Received:
    2,456
    Joined:
    Oct 9, 2009
    Location:
    Evansville Indiana
    interesting stuff. just curious, what is your experience with aerodynamics?
     
  3. Justang

    Justang Active Member

    Messages:
    847
    Likes Received:
    18
    Joined:
    May 4, 2010
    Location:
    1001110111
    So, do a buck-fifty everywhere? Got it.
     
  4. 96blak54

    96blak54 Legend

    Messages:
    7,457
    Likes Received:
    771
    Joined:
    Feb 21, 2011
    Location:
    Ky
    Excellent write up! Air sure is funny stuff!
     
  5. blackdemon007

    blackdemon007 Active Member

    Messages:
    286
    Likes Received:
    0
    Joined:
    Aug 31, 2013
    Location:
    Ohio
    Interesting, would you be able to do this study with the convertible top down?
     
  6. Wichers123

    Wichers123 Well-Known Member

    Messages:
    1,203
    Likes Received:
    0
    Joined:
    Apr 21, 2013
    Location:
    Covington, louisiana
    I'd be interested in to see what my wing does for the car.

    [​IMG]
     
  7. CrystalWhiteStallion

    CrystalWhiteStallion New Member

    Messages:
    27
    Likes Received:
    0
    Joined:
    Nov 27, 2015
    ttocs i have a bachelors in physics and am currently working on my masters degree , and i have lab grade equipment capable of calculating viscosity and fluid dynamics focused on compressible flows and turbulence analysis based on results in a mostly computational nature which is more useful in common circumstances such as airfoils on vehicles. Blackdemon 007 i'm sure we could work something out however those results may be skewed based on the interior of the car ie the saleen covers for the rear seats, seat deletes, stock vs aftermarket racing seats. Wichers 123 ya we could definitely do that however i would need some measurements among other things.
     
  8. 96blak54

    96blak54 Legend

    Messages:
    7,457
    Likes Received:
    771
    Joined:
    Feb 21, 2011
    Location:
    Ky
    I love that wing!
     
  9. ttocs

    ttocs Legend

    Messages:
    25,419
    Likes Received:
    2,456
    Joined:
    Oct 9, 2009
    Location:
    Evansville Indiana
    that's cool I was just wondering if you had any serious education behind it or if you just stayed at a holiday in.
     
  10. CrystalWhiteStallion

    CrystalWhiteStallion New Member

    Messages:
    27
    Likes Received:
    0
    Joined:
    Nov 27, 2015

    lol i completely understand and that was hilarious!:laughing4:
     
  11. Ferocious

    Ferocious Legend SN95 Supporter

    Messages:
    12,255
    Likes Received:
    592
    Joined:
    Jun 1, 2011
    Location:
    San Diego
    spoiler*

    [​IMG]
     
  12. Wichers123

    Wichers123 Well-Known Member

    Messages:
    1,203
    Likes Received:
    0
    Joined:
    Apr 21, 2013
    Location:
    Covington, louisiana
    Correction spoiler.. Lol
     
  13. 96blak54

    96blak54 Legend

    Messages:
    7,457
    Likes Received:
    771
    Joined:
    Feb 21, 2011
    Location:
    Ky
    I love that spoiler!
     
  14. lutter94

    lutter94 Well-Known Member

    Messages:
    3,011
    Likes Received:
    133
    Joined:
    Apr 11, 2008
    Location:
    South Dakota/Iowa
    Is your axle about to fall out???
     
  15. Wichers123

    Wichers123 Well-Known Member

    Messages:
    1,203
    Likes Received:
    0
    Joined:
    Apr 21, 2013
    Location:
    Covington, louisiana
    No?
    [​IMG]
    [​IMG]
     
  16. alex302

    alex302 Active Member

    Messages:
    940
    Likes Received:
    16
    Joined:
    Aug 27, 2010
    very cool! now tell me what i need to do to keep the rear bumper and tag area clean from road grim and dirt...... :-]
     
  17. Mustanger

    Mustanger Well-Known Member

    Messages:
    2,310
    Likes Received:
    115
    Joined:
    Dec 3, 2006
    Location:
    Southern Oregon
    Take two headlight washer- wipers from some furrin' car (bmw? i saw onct....mount 'em upside down on the trunk lid & put truck blades on them....hook up a line to the washer fluid & connect the wires to your brake lights! Then everytime you step on the brakes you will wash & wipe your rear....your welcome. hehe....
     
  18. ttocs

    ttocs Legend

    Messages:
    25,419
    Likes Received:
    2,456
    Joined:
    Oct 9, 2009
    Location:
    Evansville Indiana
    Do you mean the water marks that form in that area after you wash/dry the car? If this is the case its pretty easy. Take that pair of old holey socks that you have been meaning to throw out and before you wash the car open the trunk and lay one on each side. They will soak up the water that normally drips down when you drive off and prevent it from happening. Holey socks are also great for polishing under the hood. Super soft and you can get into the smallest area when you just stick your hand in it.