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Originally Posted by aerohead
1) according to Hucho the flow over the aft-body is technically compromised.
2) the 'template' can be used as a Go NoGo for attached flow.
3) in virtually every case for the non-high-performance car spoilers depicted in Hucho's 2nd-Edition, they were located in a region of separated flow. The 1st-gen Insight is compromised, for the reasons explained by Hucho.
4) the rear spoiler you've put on the Insight functions for the exact reasons as spelled out by Hucho.
5) I believe that your 'attached flow' nomenclature is amiss. There's an extremely high probability that you've mistaken 'downwash' for 'attached flow.' And for the exact reasons Hucho spells out. The sub-template Prius measured in Don Sherman's DRAG QUEENS had higher rear lift than the on-template LEAF. The sub-template, Mercedes-Benz notchback CLA 250 had the highest rear lift of the five cars measured.
6) a larger wake is of no greater drag if its base pressure is higher. For exactly the reasons as explained by Hucho. And until you master boundary layer theory, there's no way you'll ever understand the underlying premise for the template, and how it can be the canary in the coal mine of separation. Again, for the very reasons Hucho gave it to us. You may never get it. As mentioned by others, we throw buckets full of dots your way, and you remain incapable of connecting any of them. It's like terminal perspicacity - deficit disorder.
Please get a hold of Hucho and ask him about Hermann Schlicting's body of work.
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This is ridiculous. Hucho didn't "give" us a template! Here, direct from a 2010 paper Hucho posted on his own website:
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For moderate angles of inclination of the tail slope, a minimum is established for the resistance; the tip vortices are weak. The minimum is very flat and thus gives the designer a certain amount of leeway when choosing the angle of inclination. The modern hatchbacks are all in this flat area.
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His example of cars with attached flow due to vortex-induced downwash but high drag? Extreme angles such as this, yet with clearly attached tufts:
Which looks nothing like modern hatchbacks such as the Prius and Insight I.
As far as Hucho's depictions of spoilers, I'll say it again: You have done yourself a tremendous disservice by using such an old edition of "his" book (I use quotation marks because he was adamant that it is not "his"). The last edition he edited, published in 1998*, has several pages on spoilers fitted to production cars in attached flow:
This despite your often-repeated claim that Hucho wasn't concerned with lift. Note that the car referenced here, the 1988 VW Corrado, was still in development when the 2nd edition was published.
He also devotes several pages, with vector diagrams of the flow behind various car shapes, to vortex shedding from the rear.
If this was all as simple as using a template to predict flow,
there would have been no need for a 900+ page book.
* I'm thinking about dropping the money to buy the newest 2012 edition since this one is now so far out of date.