Tuft Testing Questions

[QuickLTD]

I want to tuft the nose of the car to see what the "holes" are doing but I have a few questions first. Is there a generally accepted spacing and length for the yarn? Also I will be having another vehicle filming me. Is there a recommended distance either to the side or front that vehicle should be so their wake turbulence does not seriously affect the airflow over my car? The MPH should be 50 at a minimum because Aerodynamics become active around 45MPH if my understanding is correct?

Thanks
Dean

[Daox]

Aerodynamics become active as soon as you start moving! Seriously, you don't need to get up to 50 mph. You can do your testing at 35 with no problem (assuming no winds). There won't be any noticeable difference between 35 and 50. You have to get going REEEALLY fast (think jet fast) in order to substantially alter aerodynamic flow over a body.

If you have any question about how important aero is even at low speeds, click the 'tools' link on the top and go to the Aerodynamic & rolling resistance, power & MPG calculator - EcoModder.com. This will show you your % of rolling resistance vs aerodynamic drag. For most vehicles, even at 30 mph, 50% of your energy expended is going to overcome aero drag vs rolling resistance. So, even at very low speeds, its still very important.

[QuickLTD]

Thanks for that info. I didnt realize the amount of resistance at lower speeds. I went to the link but I am unsure of line four "frontal area." My uneducated guess would be "Area (ft2 ) 24.30" but thats because of the "ft" on that line.

The same body style ran from 92-99. A 92 has a slightly more blunt bumper/grille than my 96 but this info is the closest I could find

1992 Pontiac Bonneville
Cd 0.360
Area (m2 ) 2.258
Area (ft2 ) 24.30
Cd x m2 0.81
Cd x ft2 8.75

I posted this in "Ecomodder Central" because of its description "Discuss everything related to vehicle mods here, from ideas to experiments to results." If the Mods think its better placed in Aerodynamics then ship it over.

[Daox]

Those numbers are fine for estimating purposes. This isn't an exact science.

[QuickLTD]

LOL yeah I know. I'm not trying to split hairs but I do prefer to make smarter/informed decisions.

Thanks again

[MetroMPG]

Can you explain again what are you trying to see via tuft testing? "Holes" in the front of the car?

As for being filmed, you'll want that vehicle off to the side, not at all in front.

[QuickLTD]

Sure, The upper grilles and the four lower openings. I want to put the tufts right near the openngs and around the nose in general. The factory chin air dam has been missing since way before I owned the car and I have no cooling issues so it will not be replaced. Yes the air goes through the radiator I was just illustrating that it is not sealed between the radiator support and the hood. Interestingly enough the sides are sealed between the radiator and the nose. Really I am just trying to establish a baseline for my "improvements" LOL I tend to over think sometimes.

Thanks,
Dean

[aerohead]

Id be real wary of a film car anywhere near your nose.Is there an overpass in your area that your photographer could use.My dad and I gave up trying to film our Dodge truck from another car,and we ended up with him driving the thing under a bridge overpass while I stood above with camera and telephoto lense.No wind,no traffic.You can position yourself wherever you like for the proper perspective view.---------- You can also rig a pump-up garden sprayer with remote nozzle spraying forward of the area of interest above 20-mph.Dish soap and food coloring makes the solution stand out against the body color.It dries pretty fast,leaves a "history" of where it went,and you can do that alone.

[Piwoslaw]

Originally Posted by aerohead

You can also rig a pump-up garden sprayer with remote nozzle spraying forward of the area of interest above 20-mph.Dish soap and food coloring makes the solution stand out against the body color.It dries pretty fast,leaves a "history" of where it went,and you can do that alone.

Same as driving in the winter with salt on the road...

How about mounting a camera on the car, maybe on something sticking slightly out. Maybe 2 cameras in different positions? Cfg83 put a webcam in his bumper when testing his Spring mounted Grill Block.

[Geebee]

You can buy tiny cheap spy cameras off Ebay that would be fine for this and they are the size of chewing gum pack and weight well under an Oz, so hanging them out the front would be easy and almost invisible, just do multiple runs to get the different angles.
Dont go with the 320x240 to low a resolution for clarity.