I keep forgetting that not everyone started using oil cans with "snap"
bottoms before they started to school. :-)
Jim Nichols
Tullahoma, TN USA
On 6/16/2016 12:13 AM, ChrisB wrote:
Thanks, Jim.
I had to look up "oil-canning”. I now realise that was the effect that I saw
in the skin of a Mig 29 which I saw somewhere, years ago. It was built like a battleship.
Chris
On 15 Jun 16, at 22:50, Jim Nichols <jhnichols@xxxxxxxxxxxxx> wrote:
The dimpled ribbing is primarily to add stiffness and prevent oil-canning.
Piper learned, to their dismay, in the 1960s, that raised ribs, stamped into
the sheet metal, led to transverse fatigue cracking. When they changed to
dimpled ribs, the problem was greatly diminished.
The classic vortex generator installation has the small vanes installed in
pairs, with the leading edges slightly inclined toward each other. These
produce counter-rotating vortices which energize the boundary layer to reduce
airflow separation. DeHavilland apparently felt that the flow had enough
angularity of its own, so installed them in parallel.
--
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