Am I the only one who is completely underwhelmed by this "exiting"
news that comes well timed after the June article in SSA magazine by
Bill Collum? Is anybody able to explain to me even in basic terms
what the physics behind the claimed effect are? Mr. Collums
explanations are not making any sense, he just throws aerodynamic
terms around and invents new ones such as "slip layer" that nobody
else has ever observed. How the deturbulator "detaches" the boundary
layer from the surface is a mystery and left to future generations of
physicists to explore.

I'm not an aerodynamicist (and I'm not lecturing :-), but as I
understand it, the deturbulators work something like this. On a normal
(non deturbulated) wing, where the laminar separation occurs, there is
a major change in the airflow so it can get up and over the dynamic
obstacle the turbulence on the wing poses to the flow air . This
action of air flowing up and over the turbulent layer IS for all
intents and purposes assuming the shape of a completely new (and
undesirable) airfoil. What the deturbulators attempt to do is to tame
this turbulent layer, sculpting it into a more USEFUL aerodynamically
shaped interference by vibrating at certain frequencies to manipulate
the shape/size/location of this layer. From what I understand, the
individual deturbulator panels essentially flutter at the correct
frequencies to effect this change at certain speeds, which in this
early proof of concept tests seems to be around 51kts IAS.

Again, I'm skeptical by nature and this all just
smells of Voodoo science. The claimed L/D that "peaked" at 70 to 120
to 1 (Collum article) at least I can explain: over short distances in
convective air all our gliders reach those numbers. Hell, I flew last
weekend over 66 miles at an L/D of 125 without circling and at 90mph,
according to SeeYou. Maybe the reason is that I dumped my pee-bag out
the side window before that run and the hyper-viscous fluid affected
the drag of fuselage and empennage, who knows!?

That is why tests are being conducted where the modified Cirrus is
being flown wingtip to wingtip with gliders of KNOWN performances, to
eliminate the effects imparted on performance due to airmass
variations.

This all is right now of no practical use to us. I could run all day
in Jim's Cirrus at 51 knots and still not make good speed going x-
country. In fact I would guess I spend about 30 seconds at that speed
on a typical 3 hour flight. Sorry for being so negative but again,
please show me the underlying effect. Saying we don't know right now
doesn't cut it. Come back when you can explain what you believe you
measured.

Historically, you will find many great contributions that began as
novelty ideas that appeared to the layman to have no practical value
and received much scoffing etc too. Perhaps the deturbulators will go
nowhere, or perhaps they may be the foundation of future aerodynamics.
I am glad someone is else dong the research to find out, that way I
can just fly, and perhaps benefit from this in the future.

Paul