Quote:
Originally Posted by orbywan
Thanks for some really good information Otto, I’m glad someone is actually reading this stuff.  A ‘target rich environment’, that made me laugh. That’s a good way of saying you’re (I’m) driving a damn brick.  The 15 degrees of yaw was on the Opel Calibra also, on page 183. They did say it could be more than 15, and 60 degrees of yaw looks possible in the 4.74 photo on the same page. That’s going to make for some bizarre looking fairings around the wheels. It says the yaw would be less for the rear wheels. My grandma would be loving this, yep, by guess and by golly.
Yeah, I’ve got some polyethylene foam but if the wind direction variation going over the wheels is this bad, maybe the round shape of the buckets might be better. ? So far I have not seen a need to let air in the pans, only out. When you restrict air flow this much on the underneath side, my concern is mostly for letting the air coming through the frontal area out through the pans, and various places, and not causing drag by backing the air up in there. That’s several reasons for restricting frontal air flow, especially through the front grille.
Now if I can just get the exhaust heat out without melting something I’ll be in good shape. :thumbup:
I should be ready to hang pan # 5 tomorrow and move on to the differential.  I'll be very glad when this is completed. |
I can't find my Hucho photocopied pages at the moment, but the Calibra wind tunnel picture I refer to is taken from the left front, shows longitudinal smoke trail diverts outboard at about 60 degree angle, apparently due to bow wave effect, with area of entrainment due to front wheels. So, fairings of front wheels would need to be canted in (pigeon toed) into the relative wind. Rear wheels need fairings smoothing the airflow out somewhat laterally, at a lesser angle, more or less like Prius has.
Outlets: NACA did lots of work on these during WWII. An efficient outlet is not just an efficient inlet turned around backwards. Rather, it should bring exhaust air as parallel to ambient flow as possible. Carefully study the exit gill geometry of fast swimming fishes, like tuna. Venturi and Bernoulli dynamics draw the water over the gills and out, else the fish does not get breakfast, but rather
is breakfast. With Coro panels, this should be easy. The somewhat recessed leading edge of the exit ramp should have radiused edge contour. Proper inlets and outlets make the craft into a linear pump, with no moving parts...
Hot spots around exhaust pipes, etc.: Consider paneling this part of the belly with aluminum window screen, as alu is a superb heat conductor, so instantly dissipates any hot spot. Others with Coro belly pan experience report that the stuff can be used much closer to hot spots than I had imagined, but any such Coro could be faced or edged with aluminum foil tape, similar to duct tape. For the hottest spots, alu. window screen. Might could get some suitable stuff already framed in rectangular panels from a building recycling store, or discarded after a house remodel.
Some folks report aero improvement by sealing up those gaps in the face of the vehicle. Ford Econoline vans may so profit by use of strips of polyethelene pipe insulation, properly inserted into such gaps.
Your Econoline van has a plastic valence under the front bumper exactly like mine. I've seen others with valences
that hang several inches lower, acting more as an air dam, so maybe some research at a Pick and Pull junkyard would find a bigger dam to fit that stock metal bumper, and also serve as a leading edge mounting surface for the belly pan. Alternatively, such valence could be a mounting surface for a combined splitter and belly pan. The Porsche guys figured out by trial and error that a splitter of ~4" protrusion is optimum.