"Jim Hendrix" wrote in message
...
At 04:04 10 June 2008, Ramy wrote:
On Jun 9, 5:13=A0pm, Jim Hendrix wrote:
...
Looks like the results speak for themselves and it sounds promissing.
But why does it take so long to turn it into production? According to
the web site the experiments started at 2003 and so far it was only
tested on a standard cirrus. How longer will it take until I can have
it on my 27?

Ramy

Ramy,

To be brutally frank, it's taking a long time to develop this technology
because neither Sumon nor I are very disciplined in our methods and a
great deal of hard work remains to fully understand both the flow-surface
interaction of the deturbulator device and the overall wing aerodynamics
we are achieving with it.

Sumon knows what he wants to achieve, but we are dealing with subtleties
that extend well beyond his original concept, which were close enough to
work but not really on target. I've watched his concepts morph over time
regarding both the flow-surface interaction and the wing aerodynamics
model. We now have a third person loosely associated with the project to
model the flow-surface interaction using his LINFLOW software package,
Jari Hyvärinen of ANKER-ZEMER Engineering AB in Norway.

The slowness comes down to manpower issues. Sumon is almost completely
committed to developing a deturbulator product for semi tractor trailer
rigs. As he makes improvements in the trucking device, I occasionally
divert his attention long enough to upgrade the deturbulators on my
glider. Thus, for example, we now seem to have something that sometimes
works even in the summer months, if the humidity is not too great. So the
main thrust of his attention is directed toward a, technically easier and
more lucrative, market. For my part, I have higher priorities, so the
deturbulator sort of fills in the cracks. Also, I don't have the
aerodynamics background for the fundamental work that needs to be done;
that will wait until the aerodynamics community sees the light and begins
doing the work, or large corporations pony up the funds for R&D projects.
Like me, Jari Hyvärinen needs to make a living with his normal engineering
consulting work, so for him too this is not a main priority.

Add to that the enormous amount of research and engineering that remains
to be done to fully understand the modes of flow-surface interaction that
can occur, those can be exploited for specific aims and those that must be
avoided (both are well demonstrated in Johnson's 2006 test flights-
http://sinhatech.com/SinhaFCSD-Progr...on-Details.asp) and you can
see that we have a bottle neck that is restricting progress. The sooner
the aerodynamics community takes this seriously, the sooner we will get
there. For my part, I intend to keep collecting data until the sheer
weight of it becomes undeniable. At this point in time, I am only
interested in demonstrating the concept. Producing a viable product for
use in aviation is a long term proposition, requiring real, disciplined
R&D work and funding.

The problem with treating other glider wings is that each wing is a unique
problem that has to be studied, then tested iteratively, making
adjustments
to the configuration to arrive at something what works. The process was
started with Greg Cole's Sparrowhawk, but the first attempt failed due
largely to poor quality control of the deturbulator itself (a problem that
I think will be solved with the next application on my glider) and the
project was not pursued to the point of success. My own experience, after
Johnson tested my glider in December 2006, was two failures before the
present application. And even this application was not up to par and had
to be studied with oil flow visualizations to see what the problem was. I
finally had to remove some intermediate tapes that were needed for the
Johnson deturbulators and also smooth the sharp leading edge of the new
deturbulators with (get this) Scotch tape. Finally, the first flight
after those modifications essentially reproduced Johnson's remarkable
third flight in 2006. Bottom line, it takes a lot of work and persistence
to realize success and there is too little Sinha to go around...he's a
bottle neck.

Sorry, but reality is reality!
JEH

I hope this research keeps going since it's about the most interesting area
of glider aerodynamics currently. Give these guys some credit. This is
difficult work.

Even after more than 100 years of practical aerodynamics, there are still
mysteries in extreme near field boundary layer behavior to be discovered but
there are few working in the field since the big money is interested in much
higher Reynolds numbers.

Wind tunnel data would be interesting but one suspects the deturbulator is
extremely sensitive to micro turbulence embedded in the flow. There aren't
too may extremely low turbulence wind tunnels in the Reynolds number range
of interest. Even if this were done, there would be the objection that the
data were just "laboratory results" that still had to be 'proved' in the
real world. In flight testing has it's place and it's cheaper.

What would be interesting to me would be some measurements from a static
pressure array (drag rake) behind the TE to see what changes are caused by
the deturbulator.