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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)

First successful test of Sinha deturbulator on a glider (9/17/2003)

For the Standard Cirrus glider used in these tests, the inner wing panel, from the root to the aileron, is a linear transition zone from Wortmann FX S 02-196 to Wortmann FX 66-17 A II-182. The span of the transition zone is 164 inches. The drag rake (Fig. 2) was placed at the 52 inch station (Fig. 3), corresponding to a 32% transition from the root. Measurements were taken on the lower surface only, at airspeeds from 40 to 100 kts.

Tests were conducted with the lower surface clean and with a 24 inch length of Sinha Deturbulator. Fig. 12 illustrates the results. The green curve is the clean wing and the red curve is the deturbulator test. The brown curve shows the percent reduction in drag. The greatest improvement was 19% from 55 to 60 kts. Below that range, it fell off to a few percent at 40 kts, and at higher speeds it holds steady at 10% to 12%.

Notice that the drag is represented in Volts from the pressure sensor, rather than units of airspeed that Dick Johnson normally uses. Thus, this graph is proportional to the actual stagnation pressure on the drag probe which, in turn, is proportional to the drag force on the wing. The airspeed goes as the square root of the drag force, so a graph of airspeed would not give a correct impression of the actual drag reduction achieved.

It is noteworthy that the drag reduction is more or less uniform for all airspeeds above 50 kts, with no measurable loss of performance at any airspeed. This is not surprising since, unlike turbulators, the Sinha device does not trip turbulence, taking energy out of the aircraft.

Figure 11. Sumon Sinha and Jim Hendrix
Oxford Aero Equipment offering
congratulations after first successful test on Std. Cirrus glider.
Figure 12. Drag vs airspeed* with and without deturbulator
on lower surface of Standard Cirrus wing. (9/17/2003)

Airspeeds shown in graphs are instrument calibrated. The aircraft airspeed system is not calibrated. Errors in the Standard Cirrus static/Pitot system bias the data towards higher speeds. This makes polars seem better than they really are. However, this is not an issue when the purpose is only to show comparitive data on the same glider.


© Copyright 2003-2008 Jim Hendrix