Quote:
Originally Posted by aerohead
The 'big-boys' call it aeroelasticity.
Forces acting on an under-engineered profile can actually deform it into a lifting panel, which subsequently rises to an angle of attack aggressive enough to get to burble point, then stall. The panel falls below the critical angle which initiated lift, and the 'system' begins the lift/stall cycle all over again, leading to the cyclic deformation known as 'flutter', which can bring an aircraft down.
Depending on the material, the degree of deformation, and the natural frequency, or harmonics of that frequency, the panel will just self-destruct.
There are YouTubes of model, Lockheed C-130 Hercules coming apart in a wind tunnel.
The easiest solution, yet the most difficult to fabricate, are 'compound' surfaces, where they curve in three axes. Like a hen's egg. The strongest and lightest structures have compound surfaces .
Most contemporary automobiles have some degree of compounding to their sheet metal. Strong and light!  |
That's the most readable post I've seen from you to date. No bullet points, and something resembling paragraph organization.
Last weekend I pulled a 16ft canoe on a trailer, mostly utilizing the canoe as extra storage, but also hoping to take it on the lake. I had all 4 interior sections filled with totes and tents, then covered the whole thing with 2 tarps. I tried to get them as taught as I could, but there was still some flutter at the end since it tapers so much creating that compound curve.
Seemed to be pretty aero though, as flat cruising didn't appear to suffer much in the way of fuel economy loss.
Next purchase I'm looking at a hitch mounted cargo platform for those instances where I just need more space, but not a boat. I'm torn between a sturdier looking lower profile, or the utility of higher walls.
