Porsche 928 more aerodynamic going backward?? Mythbusters to test with body reversed

[Arragonis]

Will they do the only car with a sqaure steering wheel, the Allegro next ?



Leg-end has it that it has better aero in reverse...

[botsapper]

Remember reading about that famous project by Gunter Artz, deutsch hot rodder. Great mechanicals on a much smaller & lighter platform. Even though it was widened, it was front heavy & kept the short wheelbase. Dynamically it was respectable for straight line but handled erratically because of unbalanced weight distribution and high polar moment of inertia.

http://www.youtube.com/watch?v=e8LpnhTJGY0

[Cd]

I'm guessing that those rear view mirrors are going to create some mean vortices in an already low pressure area.
The 'windshield' needs more slope.

We had a thread on this car several months ago talking of this very thing. I even did a Photoshop quickie of the car backwards with the window popped out at the 'correct' angle.
I also did a test in the Flow Simulator. I'll try to find it.

[aerohead]

Just for giggles I'm going with 'backwards.'
The Porsche, loosely designed around Ludwig Prandtl's 'Lange Car',an out-growth of Jaray's combination-form design,while not great,aerodynamically,can serve a family of four in reasonable comfort.
The 928s aft-body will make a fine fore-body. And yes,there should be separation at the windshield header and the flow might not ever re-attach,but with the nose stuffing the wake,and forcing the area the turbulence can occupy,it might be reasonable to expect an overall drag reduction.
I hope the folks at Chrysler are watching,they actually did this with the 1933 DeSoto sedan for a significant top speed and mpg increase while driving coast-to-coast across the U.S.,'backwards!

[Craig]

Originally Posted by Arragonis

Will they do the only car with a sqaure steering wheel, the Allegro next ?



Leg-end has it that it has better aero in reverse...

Or the aerodynamics of the model on the hood

[QuickLTD]

Okay, tonight is the night. Lets see how this one turns out.

[MetroMPG]

So, how'd it turn out?

I don't think we get the episode here in Canada as quickly as you guys do in the US.

[jabb]

They managed to bust the myth.
I'm not really impressed by their effort.
Testing in 1:24 shown ~9% increase in drag (if I remember correctly) - that's cool with me.
For full scale they used:
-3x 0-60mph timed runs
-3x 1/4 mile timed runs
-3x 1 mile fuel economy runs (way too short in my opinion)

Regular version of the car was unchanged.
Rotated version of the car was butchered and you could clearly see the road through wheel wells on inside shots => that could cause some extra drag O_o
I believe that they didn't pay that much attention to weight distribution when they installed weight replacements for removed parts so 0-60 runs didn't seem fair to me.

The last test when they used second 928 to compare aero by coasting looked quite decent but saying that there are no variables other than aerodynamics with these two different cars is a bit inaccurate - I was watching it in low-quality but I don't think the silver 928 has 'phonedials', same model of tires, pressures etc

Enjoyable watch, but disappointing in depth.

[MetroMPG]

Thanks for the summary.

Enjoyable watch, but disappointing in depth.

That's how I'd describe the show most of the time!

In a commercial I saw yesterday, they say they test myths "in the name of science." Not quite! "In the name of entertainment" first, "science" is definitely second.

[gone-ot]

Originally Posted by MetroMPG

Not quite! "In the name of entertainment" first, "science" is definitely second.

....yes, and, too often, it's a distant second.