update on recent events

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Sep 1, 2011, 5:33:09 PM9/1/11
to Deturbulator Google Group, Standar...@yahoogroups.com

A lot has happened over this spring and summer.


After discovering that the leading edge tapes alone, without deturbulator panels, are responsible for a large part of the performance effects that I  have been measuring for years (http://www.deturbulator.org/Progress-01152011-LET4.asp), I began identifying the separate effects of the upper and lower surface rear-facing tape edges.  This led to a surprising result when the tape went from the leading edge downward (http://www.deturbulator.org/Progress-01292011-LowerLET1.asp).  A severe loss occurred for all speeds at which the AOA was positive, < 60  kts.  Then, to avoid the relative flow ever seeing the forward edge as a rear-facing step, I lowered the forward edge 45 degrees under the wing’s leading edge.  This produced the desired result (http://www.deturbulator.org/Progress-03192011-15Cheap.asp) and the first practical outcome of this project.


Then Jari and daughter, Ann, Hyvärinen began serious work to model deturbulator flow dynamics.  They have made significant progress and have produced a small report that you can read at http://www.deturbulator.org/Hyvarinen/Hyvarinen-Summary-2011.pdf .  A formal paper will be presented to the AIAA when their work is finished.


Finally, surprisingly, other independent testing of the leading edge tapes has failed to show any change at all.  This led to the possible explanation that I sent them a variant of the Tesa 4104 tape (transparent) that does not work because of a difference in surface fiction compared to the white tape that I and others have been using successfully.  The dust needs to settle on this issue before we know for certain.  But, preliminary flight testing that I have done with both types of tape indicates that this may indeed be the problem.


The Summary page (http://www.deturbulator.org/summary.asp) has been extended at the bottom to include these recent events.


Additionally, four pilots have now reported positive results with the simple lower-surface leading-edge tape mod.  This includes comparative performance against superior gliders in normal soaring conditions.  More reports are expected in the near future, as well as performance measurements from a new independent source.


Jim Hendrix



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