Quote:
Originally Posted by Angel And The Wolf
If a boat tail extension's sides fit "The Profile", coming to a point at the back,
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The idea behind the profile, is to disturb the air as little as possible when splitting it @ the front, and then bring the disturbed flow back together @ the rear of the vehicle, with as little as possible extra disturbance added.
The profile is 3D, not 2D, and reduces the wake in all axis
So applying it in 2D, will still have some benefit, but make it less efficient than a 3D application.
Quote:
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(Figure 1), with air pressure spilling off the upper edges as it departs the boat tail, is there any significant advantage to applying "The Profile" to the upper side of the boat tail (Figure 2), or can the top boat tail follow a horizontal line from the highest point of the car, (Figure 3) without any real drag penalty?
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If you do that, you're not bringing the displaced upper flow back down to where it was.
And you need to somehow fill the void made by your upturned underside - that'll come from the side, spill down from the top, and add drag.
What was Hucho's optimum angle for a rear diffuser again ? 2-4 ° upturn ?
With the drag penalty rising sharply from around 7°-ish ?
Your rear underside rake is far too steep, too abrupt.
That's not to say it can't be done though : you're essentially drawing a very crude Morelli shape, very close to the ground for a high proportion of its length
That needs to be done far, far smoother for it to work though.
