"Jan Carlsson" wrote in message

When I said "I think" I was very humble...

I also attempt to be humble. You can always find someone smarter, or
bigger, or stronger or ..... than yourself.

Regarding winglets I am an "expert" (definition of an expert is someone
that
have read what other have don :-)

Perhaps I have more reading to do.

Peter Masak did a great pioneer work on effective winglets. result was
winglets that didn't decrease performance at high speed as the large
earlier
winglets.

Winglets make the wing act like it was of greater span,

This I know.

the improvement is
larger then if the wing was lengthened the amount of the winglets height.
And the increase in bending moment is smaller then the longer wing will
produce.

This I did not know.

Winglets and longer wings reduce the induced drag (that come from the work
of producing lift) that work is harder at low indicated speed, =slow speed
at low altitude, low indicated speed at high altitude and getting there.

So even an "high speed" jetliner will be helped by using winglets, it
spend
a long time at high weight climbing to economical cruising altitude, there
it cruise at low indicated speed (what pilot see) or more correct low
dynamic pressure.

Do you have any suggestions that I could do some more reading? I hate it
when I am wrong! :-)
--
Jim in NC