all the stuff ive done to my Scort in the past month. Ford Contour mirrors 96-99, Took the rear wing off and sealed the holes, Took all the inter out of the back of the car to get rid of ruffly 75 LBS and the door ding protectors

Tell me what you think, still in progess getting ready for rims and paint soon!!!!!!!!


Matt

let me use that wing for a little while, i want to see how it'll look on my car.

are you serious?

@matt- nice work man! I got all your texts about what you did. that car will look really sweet soon. I know your dad can do some great body work and the paint will be perfect

Wing broke when i took it off my car and no friggin way i would let you use it it looks so gay man.

Matt

of course it does, when it's purple. you never know what it'll look like on another car, it might look ok.

Joking right. Whats the point of having a wing on a front wheel drive car?

Car looks like its coming together. What color are you going to paint it?

probally wont be for a while because my baby is here now but ill be looking at gray white or blue! Not for sure im leaning more tords white and gray but i have a long time to figure it out

Matt

Front-wheel cars need traction in the rear just like any rear-wheel drive car does. Strangely enough, all four wheels having traction is necessary when cornering at high speeds. Especially in a front-wheel drive vehicle, since the ass end weighs about as much as a paper plate.

Now, whether or not Matt routinely drives speeds necessary for one, or even has the proper type of wing, is a different story.

i was about to say the same thing except in a different way.

yeah but the wing on my car looked stupid i could see i one that would actually do something working on for me but all it did was add use-less weight.
And i like they way it looks now and that i took out a lot of weight it drives a lot better now. (FASTER) not to much but i can tell a differents


Matt

raced my friend in my new ZX2 vs my old escort today kinda funny i smoked the living shit out of it!!! lol ZX2's all the way!


Matt

I never thought of that... I guess I have to look into it more cause I am pretty much ignorant right now.
But still... its like what 10 or more pounds on the back... Just leave your spare and jack in there and put some groceries back there. I still don't see it really serving a purpose, but then again I feel this way because I see alot of cars out there with huge ass aftermarket aluminum wings that lok like poo and don't match the vehicle at all. If I ever put a wing on my car it would be an OEM one.

Matt, did you get a new car? Am I missing something?

yeah pretty sure you posted in his new car thread, the yellow zx2...

as for the wing in the rear and downforce for fwd and rwd cars. the stock wing i would say is useless, on both cars. as for the tall "ricey" aluminum and carbon ones. yeah they help add downforce. they may look weird but they can greatly help hold the car down during high speeds. think of the ZX2 and im sure the neon has similar charactistics stock. throw it into a corner doing 40 or so. the car doesnt want to turn, it almost acts like its turning the opposite way you have the wheel turned. thats understeer, too much weight in the front, naturally its the first weight thrown to the outside when cornering.

rwd cars are a bit more balanced depending on the car. a lot of times because they have several hundred more pounds of weight in the back, and a little less in the front, or at least a smaller weight ratio from the front to rear. this makes their cars usually better for such things as road racing, but can be dangerous because they have oversteer, where the back end comes around and can cause you to spin...

now to tie this together. what does a wing do? next time your on the highway, stick your arm out the window and hold it somewhat straight. hold your hand out flat so its horizontal and the wind really doesnt affect your hand does it? start turning your hand so the wind is hitting your palm. notice how the closer to verticle you get the more the wind presses back? this is downforce. now consider a wing being about twice that wide and much wider... see how much pressure the wind/air is pressing down on the wing and the car? we are talking a couple/few hundred pounds of pressure pushing the rear down depending on how the wing is set up. this will also help keep that unloaded rear wheel from coming off the ground... the more rubber you have in contact with the ground, the more grip and control you can have over the car...

hope everyone enjoyed my little lesson... im sure with the calculus class im taking i will be able to give you a more accurate estimate of the downforce pressure on a given sized wing in a few weeks

Holy shit man that was a long ass post!!!!!

How is my spare car treated you?? The "Scort"

I hope it doesnt finally break down when u have it. If it does o well but i really wouldnt like to come get your ass when i get stock somewhere. lol well i hope your car looks good ill see it sometime tomorrow when i come over to get the street glow install to completion! just in time for the car show. Well everyone stop replying on this topic move too my new S/R topic to complete conversations!

Matt

Let’s start by defining what creates traction; friction creates traction, correct (assuming suspension geometry [aka wheel alignment during a turn] does not change).
Friction is...


The normal force would be the weight of the car plus the down-force (lift in the negative, downward direction).

Lift is determined by...

Dynamic pressure is determined by…

Therefore, lift (in this case the downward direction) is given by...


Let’s say the car in question weights 3,000 pounds (force). This gives 750 lbf per tire (given an equal weight distribution). Also, let’s say we want to increase traction by 10% of that having no wing, thusly adding 75lbf to a tire. Assuming the wing is mounted in the rear we will have a required lift load of 150lbf that the wing must produce. For all practical purpose, let’s use a wing that is 5 feet wide and 2 feet deep (a surface area of 5*2= 10ft. sq). Let us also assume that the airfoil section (the cross-section shape) of the wing is wisely chosen and creates a coefficient of lift that is 1.2 (a nominal coefficient for a "typical" airfoil shape). Now a required velocity (at mean-sea-level altitude non the less, lift performance decreases with altitude) can be determined to achieve the required lift load.

Calculating the required velocity yields 70 mph. That is to only create 150 lbf of down force, given unubstructed airflow, and a wisely choosen airfoil (cross-section).

KEEP IN MIND THIS IS FOR ONLY 150 POUNDS OF FORCE AT THE REAR WHEELS WHILE GOING 70 MILES PER HOUR GIVEN AN UNOBSTRUCTED AIRFLOW TO THE WING!

From a practical view, you really won't notice ANY difference at all in a practical view. It would take an extremely tuned and proficient driver who is striving to reduce lap times by hundredths of a second to notice these effects. And to mention again, the calculations I did are for a wing that has 10 square feet of area! [That is one big-ass wing to put on your civic! Go out and measure the surface area (looking from the top-down) of a Neon Sxt wing] I did a little studying of my own.

i may have missed something but where is the angle of the wing mentioned... and if the wing is only producing a nominal amount of drag... that means it not producing much downforce.... nice math though, not bashing you, just curious and wanting to know more

You forgot one thing though, CG. Your calculations are for an airfoil, not a static obstruction in the airstream. You're essentially talking about mounting an upside-down aircraft wing to a car, which isnt' what's done.

Rather, consider a piece of unfoiled metal 5 feet wide, one foot deep, proped at a 45 degree angle. You end up with a frontal face of 0.84 ft x 5ft wide. Surface area is roughly 4.25 ft^2. Assuming an airspeed velocity of 100ft/sec (just under 70mph), we end up with 4250 ft^3/sec traveling past this wing.

Air has a mass of 0.080 lbs/ft^3 (source). Assuming a near-perfect deflection (which could be possible given eddies caused by the car's body and vacuum behind the wing), the downforce from the wing alone is 340lbs! Nearly 15% of the vehicle's loaded weight, and it's concentrated in the rear alone. That's just the F=ma number from the wing having to push that much air upwards.

Of course, you also now have to contend with drag. My paper-napkin math shows me it's roughly 200 lbs of drag trying to pull the car to a stop. Here's what I came up with, please feel free to double-check me. The ZX2 at 4000 RPM in 4th gear should be traveling around 70mph: (4000 revolutions per minute / (.98 ratio * 4.10 differential)) * 2ft diameter tire * 3.14 / 5280 ft per mile * 60 minutes per hour = 71 miles an hour. Looking at a ZX2 Dyno, you can see they pull about 85hp at 4000 RPM, which is 111ft/lbs of torque. Multiply the torque by the gear ratio, and you end up with 446ft/lbs of torque at the axle. Divide it by the diameter of the tire, and the ZX2 produces 223 lbs of motive force in 4th gear at the rubber of the road.

It will be able to maintain speed with that large of a wing, and receive a significant additional shove downwards.

Well, the angle of the wing is not relevant to any of the discussion. (Contrary to popular belief, air hitting the wing and producing an opposite and equal action (think Newton’s laws) does not contribute to lift) It would only determine the maximum CL that can be attained before the airflow of the wing "separates" (aka "stalls"). a "typical" airfoil can create CL's of around 1.2-1.6 (granted I stated 1.2 in my earlier post, but the wing will not see a "clean" airflow if mounted on the rear deck of a car such as a neon so the wing will be much more inefficient for it to really even matter.) at angles (aka "angles of incidence") around 16 deg (in this case the angle is in the negative direction). The coefficient of lift (and coefficient of drag) drops as the angle becomes smaller. This can be seen by looking at airfoil data (http://www.nasg.com/afdb/search-airfoil-e.phtml)

Calculating the drag force of the wing (which would typically have a CL=1.2 and CD=0.008) I mentioned in the post would yield a drag (retarding force) of only about 1.5 lbf (while creating 150lbf of down force @ 70 mph) where 1hp = 375(lbf*mph) this is why a properly designed aircraft with 200hp (of which only about 85% is transmitted to the air) can cruise at speeds of 330+ mph very easily. Drag force is calculated by Drag= DynamicPressure*PlanformArea (the area that you would measure if you looked from above down on the wing)*CoefficentofDrag. Of course, dynamic pressure goes up by the square of the velocity. looking at a typical "drag polar" you will see a kinda parabolic curve of drag forces where drag forces are high at low speed (do to parasitic drag) and high at high speeds (do to induced drag). And is allot lower in the middle area. This would be why a 4,000hp aircraft can only go about 500mph (that’s less then 2x the speed of the 200hp aircraft with 200x the power)

Anyways, there is allot to consider and understand. Even people who do this stuff for a living never stop learning. This is all just basic principle though.

The great thing about aerodynamics is that it can create down force without adding mass to the vehicle (besides that of the lifting structures). Thusly, in hardly effects a vehicles acceleration (thing Newton’s laws again).


Note: Hopefully i keep everything straight and in order with all that i just mentioned in such a brief discussion of a complex subject.

well, the original discussion, i thought, was about "wings" (of which the stuff i talked about early covers, and are relativly useless at angles greater then about 16 deg{ that is CL falls of after about 16 deg) not "surfaces" that are subjected to airflow. so ill bite on this...

....this is @ 70 mph with a "surface" (aka "duck tail") area of 10ft. sq. at an angle of 45 deg. and treating air (which is a fluid) as if it were a solid and at an altitude of 0 feet with "standard atmospheric conditions". [also, you must remember that a pound of force is not equal to a pound of mass] of course, this theory holds true if you were throwing rocks at the "surface". but air is a fluid, not a soild. Fluids exhibit different mechnical properties then that of a solid. good thought tho. the thing with the theory of having a "duck tail" is that you create higher pressure on top of the surface creating a pressure difference just like that of a wing. (as angle increases CL falls off after about 16 deg while CD continous to increase for the surface). you would find that the drag of an airfoil will aproach that of a "flate plate" as the angle on incidence approaches 90 deg. the lift will also approach that of a flat plate as the angle of incidence approaches 90 deg.

This again is for 10 ft sq of surface. To give you the enormity of this, a neon sxt wing has an area of rougly 1.75 ft sq.

I do belive that this subject has been beaten senseless, i do not want to get into some kind of internet pissing match. im am not trying to discredit anyone or anything, just having an indepth discussion.

i strongly encourage anyone to do research on there own and not just take my word on it.

Edit: there is also a difference between power, power required, power avalable, torque, and other "forces" that are experianced by a car.

Don't worry, CG. You're more than welcome to say I'm full of crap, as long as you do it tastefully. Me being the admin has nothing to do with me being wrong in this case.

I will concede, on the fact that I was treating air as a solid, not a compressable fluid. (that, and it's been 4 years since my last physics class) Good show

Its all good dude. I pretty much hi-jacked this thread in a way.