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| Thread ID: 33295 | 2003-05-13 02:19:00 | Completely O/T.. Car wheel frictional power loss | Terry Porritt (14) | Press F1 |
| Post ID | Timestamp | Content | User | ||
| 143594 | 2003-05-13 11:41:00 | I will remmber all this when next I go out on my penny farthing. | Thomas (1820) | ||
| 143595 | 2003-05-13 23:16:00 | > besides most of the drag will be from the tire and wider tires have more drag. Been Googling and getting info from American websites, have you tweak'e? ;-) tire = US spelling tyre = NZ/Aussie/UK spelling :p :D |
Susan B (19) | ||
| 143596 | 2003-05-14 06:07:00 | My mathematical skills ceased developing somewhere between simple addition and the concept of two wrongs not making a right when I got into a dustup with another kid in the junior school sandpit, however surely this OT exercise in automotive inanity can only apply to radial spoked non-handed wheels? To my feeble mind, the counter rotation of left and right wheel spoke directions would cancel each other out, leaving only that fluid dynamics thingy to slow the vehicle down. Only really fancy ($$$$$$$$$$$) vehicles have left and right handed wheel designs, and they usually have tyre tread patterns to match! Cheers Billy 8-{) :D |
Billy T (70) | ||
| 143597 | 2003-05-14 06:19:00 | I think this question is un realistic, I mean in this day and age who buys 14" mags??? 17, or21" is much more likely :-) Seriously though, It would also depend on how much the spokes protruded from the side of the wheel as protruding spokes would add to the drag, and cause different dynamics. What is good for spokes inside the wheel may not be for those that protrude. Surely the best would be the smallest number and thinnest possible spokes (for weight minimisation) with no attack angle covered by a convex (as you look at it from the outside) lighytweight cover. Not that it matters what difference it makes when all you actually care about is how phat it makes your ride... G P |
Graham Petrie (449) | ||
| 143598 | 2003-05-14 06:20:00 | >>It is just possible that the benefits of spoilers and other add-on go faster goodies,etc, may be negated by high windage loss wheels that are designed only to look good Yes I reckon you have a point there in regards to spoilers and that. Its like modifying the exhaust system. Unless you put it on a dyno (wind tunnel for plastic bits), the engine may well be putting out less power (but it sounds like it is more powerful!) Don't you love those oversize spoilers on Jap coupes, I reckon the car would take off at 200km/hr (well the back end anyway!) |
Dolby Digital (160) | ||
| 143599 | 2003-05-14 07:05:00 | Oh, since no-one handed in their homework it looks as though I'll have to get up off my butt and do some calcs if I can find the basic properties of air. Actually Graham, the situation gets very much worse with bigger wheels, like radius raised to the fifth power. This is the basic formular for the windage power loss of one side of a disk: power= 0.5xpxr^5xw^3/Re^0.2 where p=air density r=disk radius w=angular velocity radians/sec Re=Reynolds Number The power loss varies as the cube of the rotational speed, and radius to the 5th power, so losses can increase (or decrease) rapidly. I'll come back with the results later ( It may turn out to be only a few watts, and then the whole question as Billy says will be inane) |
Terry Porritt (14) | ||
| 143600 | 2003-05-14 07:20:00 | > with most wheels it won't make any difference (unless > your turning a corner or have a strong side wind) as > the spokes on most wheels are sheltered from the > airflow by the tire. > > besides most of the drag will be from the tire and > wider tires have more drag. Also, the design of the mags, hubcaps is for asethetics only. |
Baldy (26) | ||
| 143601 | 2003-05-14 07:27:00 | > > besides most of the drag will be from the tire and > wider tires have more drag. > > Been Googling and getting info from American > websites, have you tweak'e? ;-) > > tire = US spelling > > tyre = NZ/Aussie/UK spelling > > :p :D Hey Gladys: You say potato and I say potarto, you say tomato and I say tomarto. Potato - potarto - tomato - tomarto, lets call the whole thing orf |
Baldy (26) | ||
| 143602 | 2003-05-14 07:39:00 | Correct me if I am wrong Baldy,but you seem to be saying the drag in unconfined, free air conditions is found using the equation below: CDf /CD = 1 - l 1l 3 ( 1 + (1/l )(b/c) ) cS/A1.5 – 0.5CD (S/A)(w/b) |
Thomas (1820) | ||
| 143603 | 2003-05-14 09:07:00 | > Correct me if I am wrong Baldy,but you seem to be > saying the drag in unconfined, free air conditions is > found using the equation below: > > CDf /CD = 1 - l 1l 3 ( 1 + (1/l )(b/c) ) cS/A1.5 – > 0.5CD (S/A)(w/b) > Back up the horse cart Thomas, the wooden spoked wheel is falling off |
Baldy (26) | ||
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