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TonyWilliams
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Rolling and Aerodynamic Drag Test Track

Tue Oct 23, 2012 9:35 pm

I drove to my uber secret test hill for testing of tire and aerodynamic drag. Here's an general description of the course to roll down:

Code: Select all

Sign *   Nomenclature   *  Elevation * Miles
1 - No Parking Bike Lane    * 1400ft * 0	
2 - 7% grade.....           * 1325ft * 0.2	
3 - Call Box......          * 1300ft * 0.1	
4 - Watch Downhill Speed	 * 1272ft * <0.1	
5 - No Park Bike Lane       * 1240ft * <0.1	
6 - No Park Bike Lane       * 1177ft * 0.2	
7 - No Park Bike Lane       * 1089ft * 0.2	
8 - Call Box @ Parking Area * 1076ft -neg-	
9 - 7% grade.....           * 1069ft -neg-	
10- Watch Downhill Speed    * 1360ft * 0.1	
11- No Park Bike Lane       * 1000ft * 0.1	
12- 60 mph.....             *  853ft * ? (1.5 miles from first sign)
13- Lowest point(no sign)   *  810ft * ?
14- Bike Lane....           *  850ft * ? 


So, I did several runs today. The first was stock and reached 84 mph @ check point 12, and 36 mph on the uphill section at check point 14. Elapsed time from a dead stop was 1:57.9 minutes. I tried rolling starts from numerous speeds. The cool part is that with the HUGE drag at the high speeds; it should be easy to measure changes in drag, both for mostly linear rolling resistance, and the aero drag.

I taped a box on the same spot on the "wing" that vortex generators are typically put on airplanes (see pic below). I expected some small change, but it actually limited the speed to 73 mph !!! Woo hoo !!

Now, I can swap out tires, change ride height, tape on aero mods, and other fun projects. Let me know what I should check next!


Image


Image
Last edited by TonyWilliams on Tue Oct 23, 2012 10:47 pm, edited 2 times in total.

DaveinOlyWA
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Re: Rolling and Aerodynamic Drag Test Track

Tue Oct 23, 2012 10:07 pm

this was 84 mph coasting down a hill? wow...
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Herm
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Re: Rolling and Aerodynamic Drag Test Track

Tue Oct 23, 2012 10:14 pm

How about different tire pressures?.. but document tire temperature when you do that.

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TonyWilliams
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Re: Rolling and Aerodynamic Drag Test Track

Tue Oct 23, 2012 10:19 pm

DaveinOlyWA wrote:this was 84 mph coasting down a hill? wow...
Did you notice the vertical drop in 1.5 miles? 600 feet.

Because I expect to increase speed with drag reduction, I'll have to use the lower check points to start.

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TonyWilliams
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Re: Rolling and Aerodynamic Drag Test Track

Tue Oct 23, 2012 10:25 pm

Herm wrote:How about different tire pressures?.. but document tire temperature when you do that.
Sure, that's easy. I'll swap to the old stock wheels and tires, also. Yes, document it!!

I've got to find some yarn to tape on the windshield so I can feel like a glider :lol:

Herm
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Re: Rolling and Aerodynamic Drag Test Track

Tue Oct 23, 2012 10:40 pm

If we had an accurate way to measure energy going in-out* of the battery you could find out how efficient regen is.

*that was a hint for Enginier.. a module with a good coulomb counter in it.

thimel
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Re: Rolling and Aerodynamic Drag Test Track

Tue Oct 23, 2012 10:51 pm

Please do several runs with exactly the same conditions to see how reproducible the results are.

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Boomer23
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Re: Rolling and Aerodynamic Drag Test Track

Wed Oct 24, 2012 12:55 am

Is the "daughter in back seat" condition reproducible? :D
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DaveEV
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Re: Rolling and Aerodynamic Drag Test Track

Wed Oct 24, 2012 12:56 am

Nice project!
thimel wrote:Please do several runs with exactly the same conditions to see how reproducible the results are.
I will second the thought to repeat runs to help reduce any noise. 3 runs on any setup would give you a good idea of how consistent any particular result is.

Looks like a few other good suggestions (tire pressure, stock vs Juke wheel/tire setup) there.

Since the box on roof (LOL at the unbelievable butter!) was so effective at reducing speed (no wonder roof racks kill efficiency), might I suggest folding in the side mirrors?

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TomT
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Re: Rolling and Aerodynamic Drag Test Track

Wed Oct 24, 2012 7:16 am

Next you'll need some rudder pedals so you can minimize adverse yaw! :lol:
TonyWilliams wrote:I've got to find some yarn to tape on the windshield so I can feel like a glider :lol:
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