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Sinha Deturbulator Progress Reports

Progress Articles
9/17/2003 First successful test of Sinha deturbulator on a glider
10/18/2003 Further drag reductions on Standard Cirrus wing
  Baseline polar for performance testing
2/8/2004 Progress Report: SSA Convention in Atlanta
2/28/2004 First outer-span test
5/27/2004 Wind tunnel goes into operation
8/31/2004 Stereolithography used for wind tunnel wing sections
12/3/2004 First success on upper surface of Standard Cirrus wing
12/12/2004 More success on upper surface of Standard Cirrus wing
2/18/2005 First Sink-Rate Measurement
(revised 3/13/2005)
2/26/2005 Second Sink-Rate Measurement: Some Encouraging Data
3/19/2005 First Parallel Flight - vs. ASW-28
3/19/2005 Measurements with Full Top Surface Deturbulation
9/12/2005 A Performance Endurance Issue
10/29/2005 It’s Deturbulation Time Again
1/9/2006 Paper Presented at AAIA Annual Conference
2/3/2006 Talk Presented at SSA Annual Convention
5/6/2006 Paper Presented at AAIA Flow Control Conference
7/1/2006 Notes on Endurance and the Temperature/Humidity Issue
10/21/2006 Measurements Show 20% Improvement!
(revised 1/3/07)
12/13/2006 Deturbulator Performance Confirmed!
1/2/2007 Calibrated Airspeeds
12/13/2006 Summary of Johnson Flight Test
(revised 2/10/2007)
12/13/2006 Details of Johnson Flight Test
(revised 12/26/2007)
12/01/2007 Johnson Effect Confirmed
(revised 12/26/2007)
06/7/2008 Third Parallel Flight - vs. Diana 1
(revised 8/3/2008)

Publications and Presentations
1/2006 Sailplane Performance Improvement Using a Flexible Composite Surface Deturbulator - Sinha
(PDF, 1174 KB)
6/2006 Drag Reduction of Natural Laminar Flow Airfoils with a Flexible Surface Deturbulator - Sinha
(PDF, 757 KB)
2/2007 Wing Surface Deturbulators - Johnson
(PowerPoint, 2140 KB)
2/2007 Revolutionary Aerodynamics - Sinha
(PDF, 856 KB)
6/2007 Optimizing Wing Lift to Drag Ratio Enhancement with Flexible-Wall Turbulence Control - Sinha
(PDF, 588 KB)
8/2007 Improving Automotive Fuel Efficiency with Deturbulator Tape - Sinha
(PDF, 1368 KB)


Progress Report: SSA Convention in Atlanta (2/8/2004)

Although we have done further testing of variations in the basic design and configuration of the Sinha deturbulator, these tests did not lead to further drag reductions, they merely indicated the directions we should go in the future.

With only drag measurements in hand and no aircraft performance data, we did not think we had enough to take to Atlanta. So we decided our time would be better spent working on the project. However, we were contacted by a German manufacturer who offered to meet with us, so we changed our plans and went to the convention. As it turned out, that is what we should have planned to do in the first place.

We were graciously received by four manufacturers, and doors were opened through which we hope to introduce SinhaFCSD to the soaring community. Assuming we can demonstrate that this new technology works and is feasible, we will begin working with manufacturers to adapt it to their designs. During that period we will work to refine our manufacturing capabilities. The challenge here is to meet the extremely precise dimensional tolerances that will be necessary to achieve consistent results. When we do this, SinhaFCSD will begin appearing as original equipment on new Sailplanes.

We came away from Atlanta buoyed by the openness with which sailplane manufacturers and their designers received the possibility that our composite surface could indeed provide an alternative path to performance, one that is more economical than schemes currently under development and more forgiving of wings and flying conditions that are less than perfect; i.e., more forgiving of the reality of turbulence.

So, I am happy to report that, although agreements have yet to be worked out, two of the German, as well as other, sailplane manufacturers stand ready to move ahead with this technology as soon as we can deliver it to them. I see no impediments except the challenge of manufacturing the FCS material to the necessary exacting standards. Certainly, technology is available to do this, whether or not we can do it ourselves. We prefer, however, to proceed without investor backing.

It should be noted that we have yet to take the step from drag measurments to a full performance test, and that could reveal nasty surprises. However, in our discussions in Atlanta with some of the leading aerodynamicists in soaring, no doubt was expressed that our findings are real or that our performance expectations are unrealistic.

Our plan now is to complete the performance evaluation of a full-span treatment on my Standard Cirrus, on the lower surface at least. If the results are not sufficiently impressive, we will continue to resolve issues with the upper surface and do another evaluation with both surfaces modified. Assuming we get the results we seek, we will start working with glider manufacturers to adapt SinhaFCSD to their designs, while refining our manufacturing capabilities. We expect this to begin this summer or fall.

When we have noteworthy performance improvements, we will seek independent verification. Dick Johnson has consented to test the Standard Cirrus when it is ready. Meanwhile he will be testing a SparrowHawk that will afterward be available for us. Greg Cole will work with us to find the best configuration of SinhaFCSD for that ship and then it will go back to Dick for re-testing. Mark Maughmer has offered the use of the Penn State wind tunnel. Finally, the German manufacturers will be testing by their preferred means of comparative flying against a base-line ship. We will have a busy year, and it's hard to imagine how all of this will get done. The point, however, is that by this time next year we should know clearly how well SinhaFCSD works, and how ready it is for prime time.

By introducing SinhaFCSD first as original equipment on new gliders, the manufacturers will handle certification issues as they usually do. We hope that this will ease the burden of getting STCs for retrofitting existing ships.

This is a lot of optimism based only on some wing profile drag measurements. However, it should be noted that we have velocity profile measurements, at 106 kts, on both surfaces of a laminar flow airfoil (NLF-0414F), much like modern sailplane airfoils. Also, we have integrating drag probe measurements on the bottom of a very different, older airfoil (that, incidentally, is much harder to treat) showing drag reductions across the airspeed range that are consistent with, and even better than, the NLF airfoil. This is actual flight test, not wind tunnel, results.

One additional result that has been demonstrated, though not yet publicized, is the reduction of turbulent flow, tripped at the leading edge of the NLF-0414F laminar flow wing, to a level significantly below that of the clean wing. Think about it... I leave it to the reader to see the implications.

Jim Hendrix
Oxford Aero Equipment




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