June 19, 2010
Leading-Edge Tape Alone Provides Significant Performance Boost:
On May 23, 2010 I began flying without deturbulator panels, but with the leading edge tapes that provide a rear-facing step to
precondition the flow for deturbulator operation. When experience indicated performance
enhancements of 25% for speeds from 52 to 65 kts, I took sink-rate measurements that clearly support those observations,
although the quality of the data was not good enough for publication.
This configuration offers unlimited duration of enhanced performance and resilience to harsh environmental conditions.
April 2, 2010
Porous Membrane Yields Consistent Results:
A porous polyester membrane was tested for the first time on this date. It provided another set of data confirming
extreme performance at critical airspeeds. Unlike the parachute Nylon previously tested, the polyester mesh is dimentionally stable
over changes of temperature and humidity and appears to be giving consistent results. The new material is a mesh
woven from 33 micron threads with 1% open area to purge condensation.
(
more)
August 14, 2009
Wind Tunnel Demonstration Fails to Explain In-Flight Performance:
An attempted demonstration of deturbulator performance in a third party wind tunnel was not successful. I have not made a policy
of reporting our failures, but since this test was conducted in a third party facility, I feel the need to disclose
this one. It remains to obtain measurements in third party facilities that explain the flight performance measurements by Richard
Johnson in
2006
and my own repeated measurements in
2007
and
2009.
October 2, 2008
Johnson Flight Logs Confirm Extreme Performance:
Sink rates measured by Dick Johnson and Jeff Baird in December 2006 were obtained manually,
by holding an airspeed, reading the altimeter and a timer at the start of the speed run and
reading them again at the end of the speed run. This method requires great flying skill and mental acuity, and
errors do occur. However, the deturbulator test flights by Johnson and Baird were logged electronically too.
The work of correlating the manual and electronic data is now done. Generally very good agreement was found.
Only two data points were found to be totally erroneous.
(
more)
June 7, 2008
Parallel Flight vs. Diana 1:
On June 7, 2008 the deturbulated Standard Cirrus flew parallel against a Dianna 1 to compare performance under normal soaring conditions.
Two legs were flown that totaled 20 minutes of parallel flying. On each leg, the 38 year old Standard Cirrus and the five year old
Diana 1 performed
equally well.
(
more)
December 1, 2007
Johnson Effect Confirmed:
The third test flight by Dick Johnson in Caddo Mills, Texas, on 12/13/2006
produced such extortionary results that Dick threw it out of his analysis and no one had a mind
to give it a second thought. For three months, I studied that and other "anomalies" in the Johnson data,
then argued that they were real. Now,
Johnson's third flight has been duplicated!
On Saturday, 12/1/07, the same glider, with redesigned deturbulators, essentially duplicated Johnson's third flight.
His best L/D was an astounding
64:1, a
90% increase. The new measurement was
56:1, a
67% increase.
Unbelievable as this seems, these figures are consistent with Dr. Sinha's objective and now the reality of this
achievement can no longer be ignored. Extreme performance is both possible and repeatable!
(
more)
May-June, 2007
Johnson Flight Test Evaluation Published in Soaring Magazines:
The Johnson flight test evaluation of the first deturbulated aircraft has been published in two magazines:
Soaring (May, 2007), published by the Soaring Society of America, and
Sailplane & Gliding (June-July, 2007),
published by the British Gliding Association.
(
Soaring Magazine Article (PDF))
February 10, 2007
Dick Johnson Presents Flight Test Evaluation at SSA Convention:
Dick Johnson presented the results of his flight test evaluation of Jim Hendrix' Standard Cirrus glider with
Sinha Deturbulators. Dr. Sinha also spoke, describing how deturbulators work and answering questions from an enthusiastic crowd.
Later, Jim Hendrix shared his experiences, flying a deturbulated aircraft, with visiters at the detrubulated
SparrowHawk glider in the exhibition hall.
PowerPoint files of the presentations may be downloaded from the following links:
December 13, 2006
Deturbulator Performance Confirmed!:
The day we have anticipated for three years has arrived. Although the consistency issues reported earlier
have not been solved in practice, on the strength of two recent flights
we felt that the time was right for independent verification of our claims. The gamble paid off.
(more)
September 27, 2006
Measurements Show 20% Improvement!:
Last fall we reported a return of performance with the arrival of cool, dry air.
This year it happened again. Two flights on 9/27 and 10/21 in excellent testing conditions indicate
a 25% performance improvement for the Standard Cirrus glider that we have been testing.
Furthermore, the data illustrate that large changes in performance can
result from very small changes in the deturbulator construction and configuration.
(more)
October 29, 2005
It's Deturbulation Time Again:
In this report, we provide an inside look at several polar measurements that we made
in the process of configuring the deturbulator on Standard Cirrus #60 from early spring to fall this year.
We had encountered a loss of performance with
the arrival of summer weather. We have worked hard to understand this and we think we know what
is happening. Meanwhile, with the arrival of fall weather
the deturbulator perked up again and now is now performing as before.
(more)
March 19, 2005
Parallel Flight vs. ASW-28:
On March 19, an opportunity presented itself to directly compare the cruising performance of our partially deturbulated, 35 year old
Standard Cirrus glider to an ASW-28, a state-of-the-art standard class ship. The Standard Cirrus is a first generation fiberglass
sailplane with an out-of-date Wortmann wing. Whereas, the ASW-28 represents the latest in laminar wing technology, not to mention
a low drag fuselage and empennage. The gliders were flown side-by-side for 6 miles at 92 miles per hour. The outcome was a surprising
close run.
(more)
February 26, 2005
Second Sink-Rate Measurement:
On February 18, we began taking data with an appreciable amount of deturbulator on the wings of Standard Cirrus #60. The first flight
was in poor conditions for measuring sink rates; however, the second flight, on February 26, was in much better conditions and the
data suggest good things to come.
(more)
December 3, 2004
First Success on Upper Surface of Standard Cirrus Wing:
December 3, 2004 was another very good day for the Sinha project. After working months
to resolve problems with FCSD on the top surface of the Standard Cirrus wing,
we finally realized success. Furthermore, we did this at two widely separated wing stations
with similar results, indicating that we are beginning to achieve the consistency we seek.
(more)
February 28, 2004
Outer-Span Test on Standard Cirrus Wing:
The inner panel of a Standard Cirrus wing is a transition zone from the Wortmann FX S 02-196
airfoil to the Wortmann FX 66-17 A II-182. Our first drag test on the outer airfoil
was done on February 28, 2004. The results were much like the first drag test, but more exagerated, with
drag reductions falling off at low speeds, but improving as speeds increased.
(more)
November 1, 2003
Meeting with Johnson and MacCready:
On November 1, 2003,
Jim Hendrix
and
Sumon Sinha
met with
Dick Johnson
and
Paul MacCready
and discussed the deturbulator drag reduction measurements. The occasion was the 13th National Soaring Landmark Dedication
of Raspet Flight Research Laboratory at Mississippi State University in Starkville, Mississippi.
October 18, 2003
Second Successful Test of Deturbulator on a Glider:
On October 18 a flight test yielded two positive outcomes.
First, the drag reductions from the first glider test were essentially doubled
at airspeeds over 70 kts and greatly improved below 50 kts.
(more)
September 17, 2003
First Successful Test of Deturbulator on a Glider:
On this date, Jim Hendrix tested the Sinha Deturbulator for the first time. Previously, Sinha had
measured velocity profile changes on a powered aircraft. This glider test used a Johnson style drag probe.
Tests were conducted with the lower surface clean and with a 24 inch length of Sinha Deturbulator.
The greatest improvement was 19% from 55 to 60 kts.
At lower speeds, it fell off to a few percent at 40 kts, and at higher speeds it held steady at
10% to 12%.
(more)