composites vs. aluminum

"BllFs6" wrote in message
...
So achieving laminar flow isn't easy. Getting attached laminar flow
is one of the big reason .....

This brings up a question Ive had..

A laminar flow wing is better than a non one.....

At what speeds does the advantage become significant? Or at what speeds
does it
really pay to opt for a laminar wing?

Laminar flow is easier to achieve at high Reynolds numbers and the Reynolds
number increases with speed. See:
http://www.efunda.com/formulae/smc_f...c_reynolds.cfm

Therefore the answer is that a laminar wing pays off at all speeds but is
most effective in the "drag bucket" of the airfoil in question - that is
within a range of AOA where extensive laminar flow is achieved. This range
almost always extends below the AOA used for cruise flight and almost up to
the stalling AOA.

And... is a laminar wing that happens to be dirty etc and not working in a
laminar fashion STILL better than its non laminar from the start
counterpart
wing at the same speed?

All wings have some laminar flow and none have all laminar flow. The more
you have, the better. Wing sections designed to have a large amount of
laminar flow (Laminar airfoils) are always better. All airfoils are
degraded to some degree by surface roughness. Even laminar airfoils that
are very sensitive to surface roughness will be better than one not designed
for extensive laminar flow.

It's better to think of airfoils as better or worse and not to group them
into laminar and non-laminar. Since WWII, almost all new airfoils have been
designed with the goal of achieving as much laminar flow as possible when
used in the intended application.

Bill Daniels