Quote:
Originally Posted by brucepick
Thanks. Yes I will beef it up.
I think the air impact is mostly around the middle. Based on: Before I added the stiffeners, it was bowing down in the mid section and up at the rear - but I suspect the up-at-rear might have been a kind of lever action, with the panel pivoting half way between the low and high points.
Does the bowing tell you anything about whether I put the horizontal trailing edge at the template line as I hoped to?? Or merely proves your point that it's subject to a lot of pressure?
|
If you've ever seen a soft tonneau cover on a pickup going down the highway,you may have seen how the back is 'bird-bathed' with a distinct depression,and the front is bulging upwards as if Yoda was under there trying to get out.
The depression is created by air slamming straight down on the fabric ( this is what air-cooled VWs and Porsches use for induction and cooling.
The bulge is created by the partial vacuum of the locked-vortex directly behind the cab,literally attempting to suck the fabric into it.
These forces will be present on top of your wing.If the wing is not properly 'tuned',it may reach the resonant frequency,or any harmonic of the vortex and undergo destructive flutter as can happen with aircraft.They just explode!
The reinforcement alters the resonant frequency,moving it to where it is dampened against the destructive forces.
Also,adding a short distance of roof extension will help direct the momentum of the air towards the trailing edge of the wing and not down into it.This worked very well on the CRX.