Quote:
Originally Posted by BlackGold6.4
Ok cool, this would be the gradual slope I was thinking about that I can't do to the pup because it would make to long. So another thing I saw was small "bumps" placed a few inches apart along the leading edge to kinda force the air to follow the contour down. Have any of you seen something like this. Those bumps sorta looked like the clearance lights on a HD truck but closer together.
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What you've sketched for the roofline of the 'pup' constitutes what Dr. Hucho refers to as a 'pseudo- Jaray' ( J-form ) contour, something the FKFS, next door to Mercedes researched, doing comparisons with the 'Kamm-form' ( F-form ) roofline, which takes the 'sag' out of the too-steeply sloping roof, and pushing the trailing part of the roof upwards to a more 'gradual' slope, where the airflow can reattach.
On your 'pup', you wouldn't need to 'extend' its length any, just raise the 'rear' of the roof up to better match slope of the 'cap's slope, creating a vertical, chopped-off tail, like the new Prius.
Laying a length of 1- inch diameter, Schedule-40, PVC water pipe atop the cap, and allowing it to extend out into thin air, under it's own weight would approximate a more proper contour for the roof of the 'pup.'
A 'french-curve' drafting instrument would work the best, if you could find one in this day and age.
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The 'bumps' you mentioned wouldn't be necessary if you loft the roof of the 'pup.' That alone would fix the flow separation, as you'd be creating a fastback 'Kammback', which is what all low drag vehicles have.