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01-09-2011, 06:41 PM | #19 | |
Drives: 2010 Yaris Sedan Join Date: Feb 2010
Location: Kansas
Posts: 871
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Quote:
So are you creating more hydrodynamic fish? LOL |
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01-09-2011, 11:35 PM | #20 |
Drives: Yaris 2010 Liftback Join Date: Feb 2010
Location: Massachusetts
Posts: 64
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haha. almost. i'm studying what allows fish to accelerate at such high speeds, over 20g. maybe one of these days ill try a miniature yaris in the water tunnel for fun.
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01-10-2011, 12:24 AM | #21 |
Drives: 07 Yaris sedan Join Date: Jun 2007
Location: Keremeos BC
Posts: 986
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I build and fly model sailplanes for a hobby, yet I study aerodynamics much of the time, trying to cheat a slightly better L/D ratio out of a model. Science or hobby?
As far as wind tunnels are concerned, many of us model builders have built tunnels and discovered a lot in the process, particularly in the low Reynolds numbers we work with, stuff seldom dealt with by "scientists". Also, a simple tuft test around the side of the vehicle with the mirrors in and out would show the difference in turbulence, and a camera would record the info. The actual drag coefficient would be measured in the usual way, the numbers proving any differences between the two, but again I don't think the differences would would be large enough to measure. Drag coefficient is a strange beast: there is a model of Freightliner that shows a lower C/D than a Corvette; lots of factors in there... |
01-11-2011, 01:02 AM | #22 |
Drives: 2008 5 sp. LB Join Date: Oct 2010
Location: Idahoi
Posts: 268
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I was just pointing out that any significant drag reduction on the rear end would have to be accomplished with some sort of spoiler or vortex generator full span: across the entire rear of the roof left to right. The antenna, just in the middle, may have some effect, but only on a small percent of the total area. At one time a few years ago, I saw some research being done on tractor trailers using vg's to break up the rear end suction, but I guess it didn't catch on, havn' seen any lately. I have noticed the big white plastic fairings under the trailer, it looks like to clean up the running gear drag, I see LOTS of those these days, must work.
Ain't nothing more streamlined then fish! I'd think that research would be very helpfull in general drag reduction thinking...I'm into building and flying airplanes myself, and you quickly realize less drag is always better then more power, effciency wins everytime. One reason I drive a Yaris instead of a Suburban.... |
01-11-2011, 11:37 AM | #23 | |
Drives: 3-door hatch Join Date: Oct 2010
Location: Los Angeles
Posts: 519
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Quote:
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01-11-2011, 01:53 PM | #24 |
talking about log drag mirrors... LoL
D.
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. My system may not blow your ears, but it will sweeten your senses. CLA 250, 4MATIC |
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01-11-2011, 10:34 PM | #25 |
Drives: 07 Yaris sedan Join Date: Jun 2007
Location: Keremeos BC
Posts: 986
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Any drag generator has to be there for a purpose; the point is to find out if indeed the generator needs to be there, and can it justify itself in lowering the C/D?
The water tank would certainly prove the worth of mirrors in/out. I like the position of the mirrors on the auto above; they are mostly out of the main airstream. It would take a bit of time to get used to the position: they remind me of the old peep mirrors from the 40s-50s, or the wink mirrors from the 60s. The trucking industry have been ignoring aerodynamics for decades. I suggested changes when I worked in a truck plant in the 70s, and was told first, to mind my own business, and that second, service techs would never accept their presence. That was then and this is now: in my mind, they still have a long way to go. |
01-11-2011, 11:35 PM | #26 |
pink wheels are cool
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i have these mirrors on my MR2, bomex type 2's i would love something like that for our yaris. Visibility is great with them. |
01-12-2011, 03:09 AM | #27 | |
Drives: Yaris 2010 Liftback Join Date: Feb 2010
Location: Massachusetts
Posts: 64
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Quote:
The reason I was thinking about a wing is that it is larger and easier to test in the water tunnel at my lab. The job is the same, to trip turbulence that will be helpful in reducing drag. The equipment I use has lasers measuring the movement of small aluminum particles in water to visualize the flow on a computer. However, unless if the changes are drastic, this equipment probably wont accurately show the influence of tabs on a miniature yaris. BTW, does anyone know where i can find a model yaris? |
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01-12-2011, 03:15 AM | #28 |
Drives: Yaris 2010 Liftback Join Date: Feb 2010
Location: Massachusetts
Posts: 64
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01-13-2011, 12:11 AM | #29 |
Drives: 07 Yaris sedan Join Date: Jun 2007
Location: Keremeos BC
Posts: 986
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Yeah, the test procedure leaves a bit to be desired, but us amateurs do the best we can. C/D is an easy test (regardless of the 5th wheel that the magazines use) for our purposes: results are often quite clear, like the difference between windows up or down. Besides, there seems to be a lot of confusion between drag reduction and stuff like downforce in the results of modifications. These mad machines with air dams, wings, and all the folderol on something with 100+ horses makes me laugh heartily.
Just changing brands of tires can affect C/D, hence fuel mileage. Skinning the underside has a big effect on C/D, but can also radically change handling in crosswinds, sometimes NOT for the better. Even air management at the rear has its interesting effects on drag; go to F1 to find out how far one can go with this! C/D is a huge subject with an amazing number of variables AND solutions. Keep with it, guys, it CAN be fun... |
09-30-2016, 09:50 AM | #30 |
Drives: 2007 2-door hatchback Join Date: Jul 2016
Location: USAnotCA
Posts: 750
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Vortex street shedding Tercel tracking instability generators
(Idahotom wrote:
"Vortex generators on rear of roof! I'm an airplane guy and had them laying around, and damn if they didn't make it track better at freeway speeds, my theory is that they keep the airflow more attached at the rear and not so turbulent. I wrote about it here, if you search.") I once drove some 300 miles on PA interstates covered with inches of snow because road crews were off for Christmas day. Sharp skinny 155-80/13 tires (new, but not aggressive tread pattern) on 89 Tercel EZ Hatchback w/ rear seat removed. Car wagged it's tail continuously at speed, which was disconcerting until I determined it was otherwise well planted and controllable. There were SUV's etc. that ran off the road every mile or so. Maybe 2 vehicles passed me the whole day. Idahotom: That's all advanced search here gave w/ "Idahotom" and "vortex generator." Did you post anything more about this mod? |
03-08-2017, 03:27 PM | #31 |
Drives: 2010 Yaris Sedan Join Date: Oct 2013
Location: the good Carolina
Posts: 173
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folded, they probably drag worse, really, less smooth parts that a way
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2010 Yaris sedan, TRD CAT back (sport muffler only, really), OBX header (relocated front AF sensor to front pipe), OBX throttle plate spacer, K&N filter (in stock air box-for now), TRD struts and shocks, Mexico Rough Road Springs x 4, new Yota sway bar links front, slotted/drilled rotors and Maxx brakes front, Valvoline synthetic brake fluid, 3M undercoated, 16" Konig Feathers Michelin Pilot Sport AS 3 + Tires TRD rear sway bar, 4 GT Spec bars including: front strut brace 2 point, 4 point ladder brace, mid chassis brace and rear lower tie brace, rear hitch, [B] |
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