Quote:
Originally Posted by CFECO
Rumpler, .28 so? It follows your template in plan view, if it was template in side view, it would be really something.
"If the flow is decent as far back as the A-pillars/windshield header it doesn't matter what's going on ahead of them."
Prove it. Vertical flat plate with template rear = full template, I don't think so.
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The Rumpler Tropfen-Auto was produced as an open touring car in 1921,with Cd 0.54,and an enclosed limousine in 1924,with Cd 0.28( as measured in VW's modern tunnel.
A plan-view of the car appears in Baron Fachsenfeld's book of 1951.
The body is relying on a 2-D type of flow with the air going primarily around the body rather than over.
The body itself is a 3.044:1 streamline section with 100% aft-body.
*At maximum body camber point the tangent angle is of course zero.
*At 10% aft-body length the tangent angle is 4.5-degrees.
*At 20% aft-body 8.5-degrees.
*At 30% aft-body 14-degrees.
*And from there on to the terminus the tail maintains a 14-degree angle.
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The roof in plan-view is a 2.164:1 streamline section of 0.89-width forebody and 1.27-width aft-body.
I've not put a protractor to the roof although the rear curvature is quite aggressive and just looking at the image I would presume the flow is separating by the rear axle centerline.
Flow over the roof is very good.It has a familiar architecture.
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I believe that a 3.92:1 section has the lowest Cd in 2-D flow.And little is published about 'cars' based on sections.They are more like inverted boat hulls or wingtips than sections.
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At Cd 0.28 the car was remarkable for its day however when compared to Jaray's 'pumpkin seed' of 1921 @ Cd 0.13,we have a better path to follow.