wheel discs only on the front?
Ok, can anyone answer why some cars seem to only have discs on the front?
e.g. mclaren speedtail https://car-images.bauersecure.com/p...edtail_052.jpg .. and random race car, mazda 787 https://vignette.wikia.nocookie.net/...29_-_Front.jpg I would have thought that if they were good for aero, it would be best to have these on all 4 wheels? If you were only having one axle with covered wheels, surely makes more sense to cover the rears (leaving fronts open for brake cooling?) I'm not saying these guys are wrong, i'm sure there is a whole bunch of work to come up with this set up but not sure if i understand the logic? Any one care to comment? |
The rear is in a turbulent area that doesn't improve handling with a disc?
It's not like they are fuel efficient. |
I think those style of wheel covers do two things.
1. They are aerodynamic. 2. They cool the brake via turbine fins PLUS 3. When the front wheels cut for a turn they are still doing all of the above - the rear wheels stay in plane with the body however. The rear wheels also get cooling via dedicated ductwork typically in high performance cars. An example below of turbofan wheels from the early 1980's... https://www.jdmeuro.com/tag/turbofans/ https://www.jdmeuro.com/wp-content/u...che_911_03.jpg Jan 2019 Turbofan wheels do more than just look good https://www.hagerty.com/articles-vid...just-look-good Quote:
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There is a typical pattern of the front wheels generating more drag than the rear wheels - on most cars. I'm sure that you will find an exception or two, but look for a majority pattern. https://www.simuleon.com/event/intro...-to-xflow-cfd/ https://www.simuleon.com/wp-content/...dy-768x379.png EDIT: Photobucket has blurred out the CFD of my Pick Up truck, but you can still see more drag on the front wheels. Pickup Truck Aerodynamics - CFD Study Chevy S10 https://ecomodder.com/forum/showthre...s10-35043.html http://i184.photobucket.com/albums/x...psgewe5pxk.jpg As to the cause of this phenomena, I'd wager to say there is more upset air at the front of the car as the pressure and air velocity first attempt to stabilize. Just more of a party going on up front. Keep in mind that high pressure up front means low air velocity, and high air velocity means lower air pressure. This is not very intuitive, Mr Bernoulli got it right though. Bernoulli's principle https://en.wikipedia.org/wiki/Bernoulli%27s_principle Quote:
This is what NASA has to say. What is Drag? https://www.grc.nasa.gov/www/k-12/airplane/drag1.html Quote:
Can we conclude that there is more velocity at one corner of the vehicle verses the opposite corner, or will they be equal? Do we look at pressure CFD illustrations or velocity CFD illustrations or both? Like I said, I think one needs to keep in mind that the front wheels pivot and the rear wheels do not, and maybe just leave it at that. |
Good info, kach22i. I've learned something new today.
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all wheels
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Damn.. those olds wheel covers are exactly what i want for my car :)
Some great info here - thanks chaps. I'm thinking of making my own covers, just a couple of them first. I can then try these out on front axle and rear axle separately to see which works best. I had been thinking about just adding to rear (to leave fronts open for brake cooling) but based on those cfd flow images i think that's flawed - fronts look to be most benefit. :) |
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Pizza pans are 2 stage die stamped then have the edge rolled on a can opener like device. The only reason to spin one would be you have a plywood buck pattern at home on your drilling device.
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