Quote:
Originally Posted by Jakins
so if i were to do a Bonneville spoiler how should i go about the design? something like this?
is this long enough? are these even beneficial? by the way, this will be on my road trip trunk, not my every day trunk. i want to keep a stock appearance.
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As of today,I've never seen any peer-reviewd report on these 'Bonneville' type modifications,so it's gonna be tough to assign any hard numbers to them.
Here are some talking points:
*many racers at Bonneville are aerodynamically drag limited speedwise,and are capable of wheelspin at very high speed,which can be a disaster if the car goes sideways.,lifts off and goes airborne.
*the decklid extension provides ample surface area for separated flow to re-attach which greatly increases rear downforce,which can positively affect wheelspin.
*the decklid extension also cleans up rear turbulence enough to allow the parachutes to deploy sooner which can be a life-saving difference in an impending spin.
*the decklid extension doesn't violate rulebook limitations for 'stock' body shape (even though it is technically 'cheating' when you use one).
*the decklid extension modifies any existing spanwise vortex to the good and allows streamlines further aft to recombine at nearer flow velocities and pressures,eliminating powerful longitudinal attached vortices.
*while the extension modifies the 'upper' flow,it does nothing about the separation point at the body sides and bottom,which will in turn determine the pressure of the entire wake (so the extension cannot provide the benefit of a boat tail which alters the entire separation point on the car).
*as you can see from your own graphic,it would require an enormous extension to reach out to the 'Template'.
*if you wanted to 'experiment',run your extension out to any length you can live with,and then go 'half-way' vertically to the 'Template' with a 30-degree upswept 'kicker.'
*I've observed a few high-performance cars which have done something like this.
*you buy some effective length by raising the trailing edge of the extension up.(it could be done with clear Plex. or Lexan bent on a gentle curve [when viewed from above],allowing you to 'see' through it when backing).
*if you extended your C-pillars out to the back of the extension as buttresses,you could additionally tailor the captured-vortex with these 'capping-plates.'
*also,if you go ahead and boat-tail the decklid extension it would be easy to do a follow-on box-cavity or proper tail extension at a later date.This is where your money is hiding.
