Aero Crosstour- Squeezing blood from a stone

[Chonk_Master]

Right. Maybe should have said "it's only one component of the equation".😄

Thanks for the tip. Is the RGB going to give number of pixels? I might be able to work that into an actual square inch measurement.

[Ecky]

Originally Posted by freebeard

It's a multiplier.

Find a black on white silhouette of the two models, apply a Gaussian Blur filter to it's max and read the RGB value for each. The difference should be proportional without a lot of fussy outlining.

Or you could go into a parking lot and wrap a rope around someone else's 2nd gen Insight at its widest point, and measure the circumference. Do the same with the Crosstour.

Cd is a coefficient, it's multiplied by the area of the vehicle that faces the wind to get drag. A vehicle's size does not impact it's Cd. CdA (coefficient of drag x area) is larger on a large vehicle, however.

[freebeard]

Thanks for the tip. Is the RGB going to give number of pixels? I might be able to work that into an actual square inch measurement.

Both would be reduced to a uniform gray. The lighter gray will be some percentage different to the darker one. This would be approximate, the advantage is one might be able to do it without getting out of the chair.

I like the rope idea.

[Chonk_Master]

Got it. xD

I'm gonna' see what I can do with MIPAR. I can definitely get the Crosstours cross-section with that. I might be able to do it with the Insight's if I can find a photo with something that can be used as a scale in the shot.


.....actually, is the width of a vehicle taken at the side mirrors or the body? I could use the car itself as the scale.

Edit: looks like that's without mirrors. Might have a solution here.

[Chonk_Master]

04/16/2020:
Okay, larger update.


You're looking at probably the worst CAD mockup of anything ever and the sum of all my concentrated effort and skill.

Pretty excited about it, nevertheless. Plan is to start a print of a prototype (probably 5% infill, 1 mm thick walls) tonight and test fit tomorrow. If it works, I'll print a more substantial version (say, 10% infill 2 mm thick walls) for the road. This is the passenger side. The driver's side will just be a mirror (zing) image of this model.

The side with all the reliefs faces the interior of the recess left by the old side-view mirror mount. I'll be heat setting threaded inserts, mentioned earlier, to this face to create mounting points that are same as factory.

The tricky parts is going to be mounting the low-profile side mirror. The shape is not so straightforward as this mounting plate. You can see there's some curves and bends that would need some really good measurements and patience if I wanted to build a recess into the flat side in CAD.

The other option would be to router is out, which might be worth it to try on the prototype. I also thought I could maybe heat set it but I'm pretty sure that'll be too much heat for a piece of metal with that much paint on it.

There's factory weather stripping and foam that will hopefully make everything snug. I'd like to also cut out a thin piece of rubber to place underneath this plate to seal up the interior from road noise. Shouldn't be too hard.

[Chonk_Master]

Fits, barely. We're printin'!

[aerohead]

Originally Posted by Chonk_Master

Got it. xD

I'm gonna' see what I can do with MIPAR. I can definitely get the Crosstours cross-section with that. I might be able to do it with the Insight's if I can find a photo with something that can be used as a scale in the shot.


.....actually, is the width of a vehicle taken at the side mirrors or the body? I could use the car itself as the scale.

Edit: looks like that's without mirrors. Might have a solution here.

The mirrors are not factored into the body width.
The frontal area ought to be around 85% of the gross area (HxW).

[Chonk_Master]

Ah, interesting. Is that kind of an observed average?

[freebeard]

Prolly an edumacated guessimate.

Worst possible case would be Thee Holy Template: 78%.

Box van: ~100%

[aerohead]

Originally Posted by Chonk_Master

Ah, interesting. Is that kind of an observed average?

For the few times where actual frontal areas have been published recently,they're in the 85% of gross area region,as tires get wider.
A forgotten analog,photographic technique for acquiring Af, is by weighing the (net) 'cross-section' of the vehicle,cut from a photograph of it,then comparing its weight to that of the total weight of the (gross) cross-section it was cut from.A laboratory-grade scale is required.