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Dr. Sumon K. Sinha has developed a Flexible Composite Surface Deturbulator (FCSD) tape, and a method for integrating it with aircraft wings to substantially enhance aerodynamic lift and reduce drag. Although development is proceeding, Dr. Sinha's Deturbulator has already indicated a 20% increase in total aircraft lift/drag ratio, as measured on a Standard Cirrus Glider. Dick Johnson confirmed 18% with his own independent measurements in December, 2006 at Caddo Mills, Texas. A close look at his data, taking into account variability in the prototype deturbulators used, reveals a performance increase of 25%. The additional 5% was due to Mr. Johnson's use of total airspeed system calibrated airspeed values rather than the instrument calibrated airspeeds used earlier.

Dr. Sumon Sinha

Increasing the glide ratio translates to fuel savings, increased speed, increased range and/or increased endurance. This would not only help airlines maintain profitability in the face of stiff global competition and increasing fuel prices, but also improve the performance of sailplanes, general aviation aircraft and unmanned aerial vehicles.

Even though this flexible tape resembles the much investigated and fairly unsuccessful attempts to reduce skin-friction drag with compliant walls, the method of interaction and resulting drag reduction and lift enhancement mechanisms are very different. In the presence of the spatially varying flow pressure gradient found on wings, the strategically located Deturbulator tape helps maintain a thin and nearly stagnant air layer ("slip layer") next to the wing surface over a wide range of operating conditions. It does this by reducing selected turbulent fluctuations. Unlike well known laminar-flow-control methods, it does not try to keep the flow completely laminar. Neither does it directly attenuate turbulent mixing over the entire flow surface. Deturbulator simply lifts the main flow a very small distance above the wing surface, thereby reducing viscous losses. Drag reduction and lift increase result.

Close up of experimental FCSD tape
Laminar flow is often construed as the optimal boundary layer condition, the best that can be achieved. Laminar boundary flow does indeed minimize turbulent energy losses; however, skin friction still exerts drag forces at the bottom of the boundary layer where the velocity gradient is steepest and viscous losses are greatest. By lifting this layer ever so slightly above the surface and delaying reattachment as far as possible by reducing turbulence, greater efficiencies can be achieved than pure, attached laminar flow can deliver. In fact, it is not necessary to have purely laminar flow to realize remarkable drag reductions. This is the fundamental concept in the Sinha Deturbulator method. Instead of attempting to achieve laminar flow, this approach accepts turbulence as a fact of life and seeks to manage it in beneficial ways. The result is robust performance in the face of imperfect flight conditions. Dr. Sinha has measured drag reductions even when tripping the flow at the leading edge of a wing.

A series of wind-tunnel and flight tests on two aircraft have both verified the flow-device interaction mechanics and indicated the possibility of using deturbulators to improve the fuel efficiency of existing commercial jet aircraft at least by 5% based on recent results. The significance of this lies in the fact that competing devices such as riblet-film has shown a modest 0.8% drag reduction. Blended-winglets claim 7% drag reduction on business jets but require significant expensive structural modifications.

SinhaTech has obtained competitively awarded R&D funding for this work from NASA and NSF. These have culminated in developing the Deturbulator technology to a point where SinhaTech plans to offer it to low speed aircraft like sailplanes and experimental aircraft in the near future.

News Archive

June 7, 2008

Deturbulated 38 Year Old Glider Matches 2005 Model
On this date, Jim Hendrix flew his deturbulated, 38 year old Standard Cirrus glider against a 2005 Diana 1 that performs with the best gliders available today. For 20 minutes the flew in formation and matched sink rates from beginning to end. This was a remarkable demonstration of the capabilities of deturbulator flow control in real world flying conditions.   (more)

February 14, 2008

Hendrix Speaks in Albuquerque
Jim Hendrix presented the case for extreme performance at the 2008 SSA Convention in Albuquerque. He presented data showing that Dick Johnson flew at 100:0 for 1.2 minutes. He also presented oil flow images confirming the existence of slightly detached flow that eliminates most of the parasitic drag from both wing surfaces.   (PowerPoint Slides)

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)

June 25-28, 2007

Sinha Paper presented at 18th AIAA Computational Fluid Dynamics Conference
Dr. Sinha presented a paper titled Optimizing Wing Lift to Drag Ratio Enhancement with Flexible-Wall Turbulence Control at the 18th AIAA Computational Fluid Dynamics Conference in Miami, Florida. In this paper he reveals fully the intended flow-surface interaction of his Deturbulator and the revolutionary efficiencies that can be achieved by creating an edge-to-edge "slip layer" that essentially eliminates viscous flow losses.   (Read Paper (PDF))

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))

March 6, 2007

Deturbulator Kits to be Available for Gliders
Dr. Sinha had decided to provide prototype Deturbulator kits to sailplane owners are eager to give it a try. A unique kit will be developed for each glider type. It will include materials and instructions as well as procedures for testing the performance of your glider.   (more)

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)

February 3, 2006

Talk Presented at SSA Convention
Dr. Sinha presented a talk entitled Revolutionary Aerodynamics at the 2006 SSA Convention in Arlington, TX. He spoke to a packed room of interested people, describing his approach to improving wing performance by reducing the skin friction component of boundary flow and increasing lift. Dr. Sinha described his work in a non-mathematical way, while showing considerable amounts of wind tunnel and flight data.   (more)

January 9, 2006

Paper Presented at AIAA Conference
Dr. Sinha presented a paper entitled Sailplane Performance Improvement Using a Flexible Composite Surface Deturbulator at the 44th American Institute of Aeronautics and Astronautics Aerospace Sciences Meeting and Exhibit on January 9-12, 2006 in Reno, Nevada. This paper gives an in-depth look at Dr. Sinha's deturbulator research over the last three years using Standard Cirrus #60 as a test vehicle.   (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

First Parallel Flight Evaluation
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)

August 31, 2004

Stereolithography Used for Wind Tunnel Wing Sections
In our search for ways to make accurate wing sections for Dr. Sinha's wind tunnel, we settled on Stereolithography (SLA) as the means for obtaining the correct basic profile.   (more)

May 27, 2004

Wind Tunnel Goes Into Operation
This month, Dr. Sinha finished construction of a wind tunnel that will be used to advance work on the deturbulator project. He is proceeding to measure the aerodynamic characteristics of this new tool and to use it in taking data for his NASA Langley project. Later, it will be used to study issues related to manufacturing SinhaFCSD and applying it to various aircraft wings.   (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)

October 18, 2003

Second Successful Test of Sinha 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 Sinha Deturbulator on a Glider
On this date, Dr. Sinha tested his deturbulator for the first time on a glider. Previously, he had measured velocity profile changes on a powered aircraft with a laminar flow wing. The 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)

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