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Originally Posted by jimepting
Found a Fit today over in the Lowes lot while looking for grill block parts  NOW I see what you are talking about. Stand behind the Fit and the morphing into a better transom shape is very apparent. When I got home I stood behind my Gen 1 Insight and decided that the Insight had done a much better job, but of course they didn't make nearly as many compromises. Now you are making me want to put some tell tails on the corners of the rear to see which way the flow is going.
Do you think the Insight is cursed with the longitudial vortices at the upper corners of the rear (i.e. the corners of the tail lights)? |
I measure a terminal exit tangent angle of 14-degrees on your Insight,which is knocking on 'ideal' contour.What I suspect,is that the yarn might orient itself towards the roof near the side/roof intersection but I don't think you'll find vorticity.Just strong downwash and inwash at near identical velocity.There was a brief moment in the wind tunnel video of the Insight when they went across the side mirror with the smoke and if memory serves me,that while perturbed by the mirror,the flow stabilized where you would suspect vorticity to be present ( can I trust my memory?)
In Hucho's 2nd Edition,in Chap.4,'Analysis of aerodynamic drag' he says only "surfaces must be matched to prevent high pressure variation along the flow path."This is where the wind tunnels pay for themselves!
In his Fig.4.14 he shows a drag maximum @ 30-degrees down-slope,with high vortex induced-drag.If the slope is increased,the downwash bursts the vortices and the wake changes over to a squareback type wake.
I think HONDA's done such a good job that you're not at risk.
Tell tails on the side of Kamm's lowest drag 1939 K-5 show precursor 'hunting' towards the roof.Hucho's wind tunnel photos and the ones VW sent me of the only surviving K-Car show zero vorticity,just turbulence.The Landsberg Castle K-Car and K-5 have similar roofs.