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Old 05-14-2022, 09:26 PM   #281 (permalink)
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I suspect you'd have to be extremely diligent to discern small aero changes with a 25mph coast down test
That's why I suggest not doing it.

Time to a given goalpost, or distance to a given speed?

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Old 05-14-2022, 10:01 PM   #282 (permalink)
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Does the Ionic report a consistent load for the scan gauge even as it switches between gas and electric? If so you could do A B A testing using cruise control resume and recording the load...

I haven't found one for the Prius yet, the one I added seems tied to the gas engine alone and misses when the electric motor is being added...
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Old 05-14-2022, 10:04 PM   #283 (permalink)
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Quote:
Originally Posted by Phase View Post
Hereís a random idea, tell me if itís flawed,

Say I find two markers or objects, like street signs or light poles or whatever they are maybe a quarter mile apart?

I drive to 70 miles per hour, and when I get ti the first check point, put it in neutral and start a timer. Then measure how many seconds it took to get to the second check point. Do it a few times for an average.

Then put on the aero mod, and do the same exact test, and if it took less time to reach the check point, even by 2-3 seconds, that clearly means the aero mod is working right?

Or is that test idea bad?
That should work to see if the mod helps, hurts, or doesn't make a noticable difference.

It probably wouldn't be precise enough to try and experimentally determine drag & rolling resistance coefficients.
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Old 05-14-2022, 10:25 PM   #284 (permalink)
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Originally Posted by Drifter View Post
That should work to see if the mod helps, hurts, or doesn't make a noticable difference.

It probably wouldn't be precise enough to try and experimentally determine drag & rolling resistance coefficients.
well i'm not trying to get an exact numbers and precise measurements and formulas. just everything i can do to improve fuel economy. anything that helps, ill take
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Old 05-16-2022, 10:02 AM   #285 (permalink)
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expensive

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Originally Posted by Phase View Post
geez that sounds expensive. im trying to go the cheapest route
For sheet metal, see if local metal recycling centers allow salvage.
Also, commercial sign companies may have aluminum signs removed from client's buildings when signs were upgraded.
As Joe Walsh says, ' That's what I do.'
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Old 05-16-2022, 10:26 AM   #286 (permalink)
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spoiler

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Originally Posted by Phase View Post


any idea why the ioniq 6 coming out would add that random spoiler halfway down the back? why not just let the air flow stay attached? wouldnt it be more aero to keep it smooth?
I failed to locate a decent photograph or technical image of the IONIQ 6.
There's no way to 'analyze' it without.
1) It's silhouette is similar to the 'Prophecy' concept car.
2) The Prophecy is Porsche 911-esque.
3) It has a pseudo-Jaray aft-body inclination, @ 26-degrees.
4) The rear spoiler knocks that down to a virtual 13- degrees, right on the AST-III.
5) Theoretically, the Prophecy would have issues with a transverse C-pillar vector-induced, attached longitudinal counter-rotating vortex pair, itself, inducing downwash and 'false' attachment, at the expense of strong, fastback vortex drag.
6) The Prophecy needs the spoiler to burst the vortices, kill lift and drag.
7) Porsche stopped using this contour on the 911 in 1993.
8) So, technically, the flow wasn't attached, and the spoiler is, as Ferrari calls it, a 'kludge.'
9) If the GENESIS division adopts the IONIQ 6, as ACURA borrows from HONDA, we may see a Taycan-killer based on this architecture, at slightly less than a PORSCHE price.
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Old 05-16-2022, 11:02 AM   #287 (permalink)
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road testing

I'd give up on trying to quantify delta-CdA for anything small. That's what wind tunnels are for.
If, say, you have 'smaller', 'higher fineness ratio', and 'further-distanced' mirrors from the car, you might just presume that there's an advantage.
You really can't afford to 'know.'
Old-school road testing requires a thermal stabilization period of 30-minutes, driving 50-mph, before you ever begin the actual testing.
1) Calm ( or not to exceed SAE specs )
2) Dry
3) Straight
4) Level
5) 10 runs, back-to-back, with each configuration
6) Continuous time-stamped weather monitoring
7) 1/10th-second recording resolution.
8) Coasting through 70-mph, down to 20-mph
9) 5th-wheel data transmitter ( mechanical or optical )
10) Data-logger/ strip recorder
11) Done to SAE Handbook specifications.
12) You may prefer root canals to the mathematics required for data reduction.
------------------------------------------------------------------------------------
I bailed, and just paid CAR and DRIVER to do the tests at the Chrysler Proving Grounds. Between that, and Bonneville, and lots of tank mileage, I eventually got some numbers that told the tale.
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Old 05-16-2022, 11:10 AM   #288 (permalink)
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Quote:
Originally Posted by aerohead View Post
I'd give up on trying to quantify delta-CdA for anything small. That's what wind tunnels are for.
If, say, you have 'smaller', 'higher fineness ratio', and 'further-distanced' mirrors from the car, you might just presume that there's an advantage.
You really can't afford to 'know.'
Old-school road testing requires a thermal stabilization period of 30-minutes, driving 50-mph, before you ever begin the actual testing.
1) Calm ( or not to exceed SAE specs )
2) Dry
3) Straight
4) Level
5) 10 runs, back-to-back, with each configuration
6) Continuous time-stamped weather monitoring
7) 1/10th-second recording resolution.
8) Coasting through 70-mph, down to 20-mph
9) 5th-wheel data transmitter ( mechanical or optical )
10) Data-logger/ strip recorder
11) Done to SAE Handbook specifications.
12) You may prefer root canals to the mathematics required for data reduction.
------------------------------------------------------------------------------------
I bailed, and just paid CAR and DRIVER to do the tests at the Chrysler Proving Grounds. Between that, and Bonneville, and lots of tank mileage, I eventually got some numbers that told the tale.
For some of my more mild mod testing, Iíll be driving out past the Columbia gorge over and hour away on a stagnant air day. Engine should be warmed up and I should be able to do coast down testing starting at 90 mph. Itís middle of nowhere and long and flat. May also try some throttle stop testing on top of the coast down testing just to cross examine the results
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Old 05-16-2022, 11:20 AM   #289 (permalink)
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testing

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Originally Posted by Phase View Post
For some of my more mild mod testing, Iíll be driving out past the Columbia gorge over and hour away on a stagnant air day. Engine should be warmed up and I should be able to do coast down testing starting at 90 mph. Itís middle of nowhere and long and flat. May also try some throttle stop testing on top of the coast down testing just to cross examine the results
I'd have some things to say, but I believe that I'm still under a gag-order, and not allowed to discuss particular things.
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Old 05-16-2022, 11:44 AM   #290 (permalink)
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some tentative numbers

I went ahead and spent some time with the IONIQ blueprint:
1) As a 1st-approximation, the extension to your existing spoiler, beginning @ 1162.6mm from the ground, would fall away @ 16-degrees.
2) @ 12-inches from the 'so-called' diffuser, the curvature of the upper surface would morph to 16.5-degrees inclination, @ an elevation of 1033.3mm from the ground.
3) @ 24-inches ( if using a receiver-hitch-mounted cargo carrier ) the curvature would have drooped to an 18-degree inclination, @ 935.5mm from the ground.
--------------------------------------------------------------------------------------
4) The diffuser would follow the line which exists at the bottom of the rear quarter panels, rising on a 2.8-degree inclination.
--------------------------------------------------------------------------------------
5) The sides of the IONIQ follow different cambers, bottom, beltline, and roof top. Each would follow curved pathways specific to their starting conditions. The most complicated portion of the elongation. The idea is to get it 'right' the first time.
6) See if you can locate: US Patent 8590961, February 21, 2012. Look how Breidenbach handles his boat tail. Your scheme would be similar, but you'd want 'curves', not just flat planar surfaces.

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