LOL Jay and Silent Bob?

"I don't know what you just said, little man. But it touched my heart!"

 

Auto manufacturers only use frontal area??? Seems odd tome that around say 88 whent the new Olds Cutlass Supreme was out in its front wheel drive glory they mad a big deal that the new Aero shap actually had better numbers than an F-16. Only through careful shaping and great extents of minimizing drag causing features such as sharp edges did they manage this feat. Hmmm.

So going with true frontal area we can though assume that adding anything to the front will increase drag. So spoilers should be left off. However this does not allow for turbulence drag on the under carraige for which many a race car has seen many hours of work.

Remember that when card go to high speed and they want to minimize drag they do what they can to pull the spoiler out of the air stream or lay it as flat as possible.

 

The only question I have is why would you need to worry about drag as much as you are when you're going to be racing road courses. I'm no areospace person or anything but...

 

Yeah they use frontal area for determining the drag cofficient - I think you are confusing the fact that a streamlined vehicle with the same frontal area as one which is not will have a lower drag coefficient and therefore a lower induced drag force. Its just a characteristic area that is used for comparing drag coefficients and keep in mind that 2 vehicles with the same drag coeff with different frontal areas will experience different drag forces - the one with the larger area will obviously be greater. Adding air dams increases frontal area but hopefully reduces the drag coeff with the net result hopefully being a lower drag force; I know this seems confusing but thats just how it is described, I dont make the rules, I just play the game....

 

Well for the simple fact if you add front and rear airfoils to give some downforce, they are going to ADD drag - so I was curious to look into this to see if the whole aero package could be put together to make up for some of induced drag from wing(s) by controlling the way the air moves under the car, hits the front of the vehicle, and rolls off the back - I have researched this and I dont see there is any way possible to completely counteract the added drag of wings which provide downforce, only maybe to slightly reduce it and therefore have a better balanced aero package. I dunno just a thought....

 

No one really answered your question about drag reduction. That was a nice dicussion between you and WingViper or should that be Vapor. But anyway the answer is Y-E-S. I'm interested in reducing drag on any vehicle. My problem isn't with a Neon it's with an older jeep with a full cab. Since it's not really airtight at the gates I get exhaust gases coming into the cab when I roll down my side window, very disturbing. There are new seals but some cracks and I don't know how successful a guy could be totally sealing the rear gates on this model. So I was thinking of a spoiler to prevent the exhaust gases from building up and being sucked along by the vehicle, vacuum drag. I was thinking about using about a 2 or 3 inch high by width of cab by 3/4 inch piece of wood attached to the rear of the roof. This would also be adjustable for angle to see which angle is most effective at preventing the gases coming in. I'm hoping this would break the vacuum. The other thought is vents that would direct the flow of air downward across the rear window. There are drag vents available for semi's hauling large containers and trialers.

My thought is to first tape some long strings on the roof and see how they flow behind the vehicle to kind of map out the problem then attach the spoiler and see how the strings react.

MJM

 

Ahh finally!!! yeah man that would be perfect - I dunno if I would use wood but I can see why you would if you dont want to spend alot of money - the jeep should actually be fairly easy to tell if youve made any improvement because their aero is certainly less than ideal - adjustment of the angle should change its characteristics at different speeds but be weary of goin too steep or high because you will induce more drag. I think because you have such a flat rear section on the jeep that you would see significant improvements in highway fuel economy when you get it right - another problem with jeeps is flow seperation at the hood, a curved (bug) deflector could help to minimize this but I have no real confirmation that it would...you know if you want to get tricky you could try to incorporate the vents into a spoiler and redirect some of the air downward and the majority of it off the spoiler lip and away from the back of the vehicle - I know exactly what your are talkin about with semis cus drag reduction is HUGE with them, unlike mr vipers snide remark in that drag reduction is for stuff that really matters...I think it matters to the truckers how much money they spend a year on diesel!! There are some great papers out there on this subject and seen as how your rear geometry is much like a semi trailer I would use any info I could dig up on this...keep in mind tho that the jeep is much much shorter and this will affect the boundary layer thickness at your trailing edge...good luck and if you need any info I will be more than happy to provide you with some..

 

Well thanks for the offer. I'm using wood for a few basic reasons, it's cheap, easy to form and attach, if I don't like it, not much is lost. There is a lot of room for improvement on this vehicle. The windshield is practically vertical and flat. The removable cab sticks out in front of the windshield making a pocket for noise and drag. The rain gutters on the sides of the front windshield stick out about 1/2 inch creating a bunch of noise. Noise equals drag to me. These will be filled with a taper strip the height of the windshield. I have no idea how to deal with the overhang of the cab and the windshield. A large round filler?
The idea of a bug deflector on the front hood is a great idea if I can find a universal fit it could solve a lot of problems with a simple solution. The hood has kind of a unique fit. It comes to a rounded, about 1 inch in diameter, edge that when it closes comes down on a neoprene feather gasket off the grill. It's a 4x4 so we've got all that drive-train being pushed along maybe an airdam or a streamliner? This is where WingViper theory kicks in... bigger motor, more HP and torque to over come the drag more easily equalling better MPG. I'm stuck with 304cid, a 360 has the same block etc., I wish this was a 232 or 258 six, there's a lot of goodies for these.
I've been looking at factory installed spoilers and wings. Some are there more for the appearance I'm sure, others look effective. A Chev surburban has a deflector that runs above the rear gate directing air over the rear window, probably keeps the dust and dirt off. A toyota highlander (?), they make so many suv's I can't tell, has a shelf projecting about 1.5 inches parallel to the roof and looks about like my front over hang. I don't know if this is effective or just design. The air might "drop off" that ledge and start tumbling, reducing the vacuum.
So, this being a "long" weekend maybe some experimentation might get started, attach a few strings. Yesterday I removed the carb for the seemingly one millionth time looking for a clogged artery and finally a big chunk of ancient debris come out. I've cleared those passage I don't know how many times and chunck would move just enough to make you think that passage was clean, but 200 miles later vacuum and rpm at idle would drop. Now for a call to my local transmission store to find out if a 1973 TH400 can be brought into the modern world with a shift kit and tighten things up.

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