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Old Nov 26, 2012, 02:17 PM
BMatthews is offline
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The 'Wack, BC, Canada
Joined Oct 2002
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Well, again things like notches, sawteeth and other add ones are typically functioning as turbulators. And turbulators do not in themselves increase anything. They are there to "fix" airflow separation problems and to some extent delay the stall.

So it might just be that your APC prop did not have anything that needed "fixing" over the range of operation that you used. Perhaps try buying a Master 9x6 and run the tests again without notches and then try notching the blades similarly to that in this report. Perhaps then you'll see some improvement. The next question up is will the MA prop with improvements due to the notches exceed the performance and efficiency of the stock APC? It may be that all this "fixing" only allows the MA to come up to or nearly to the performance provided by the stock APC.

When a buddy and I ran some static tests on props and motors back some 20 years ago we found that it was pretty tough to beat the thrust to power ratio achieved by the APC props. The MA props similar to that used in that report were consistently down in performance compared to the APC's. So it may be that the MA shape has issues which were "fixed" by the addition of the turbulators in the form of the notches where the APC has nothing that needs fixing. That would explain your results.
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