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Posted by Waterbug | Jan 31, 2009 @ 11:58 AM | 2,378 Views
I measured the before and after props' pitch angles with a goniometer. No, thats a thing that measures angles, pervert! Some call it a machinist's protractor- it has a settable angle bar that I can bring up against the back of these undercambered blades. I measured the factory APC10x3.8's angle on the back of the prop blade "mid span" at a radius of 2.5". I got 14 degrees which is a pitch of 3.9. Due to the undercamber, taking the back half of the blade off drops the measured angle to 12 degrees. That calculates to 3.3 pitch. No wonder why it hovers so nice. Never did want my foamie to scream, so the lower pitch works great.
Posted by Waterbug | Jan 03, 2009 @ 03:54 PM | 3,366 Views
My Motor test data compared to that of Dr. Kiwi attached.
Like his data, these are measured voltage while the amps were being drawn, i.e. true wattage.

Dr. Kiwi's data is represented by the red curves near the top of the graph.
My data is the rest on two motors, and 3 props at two different voltages corresponding to 2s and 3S lipo.

Motors: Esskay 400XT and Lazertoyz.com Blue Wonder 2712-12
Props: GWS EP 9050 APC 10 x 3.8 stock and APC 10 x 3.8 modified
the modification was to trim the back half off of the blade, chopping it from a wide blade to a narrow blade. I wanted the ultimate hover prop but the stock APC drew too many amps. There's also a singular data point for an APC 9 x 4.7 which flies very similar to the GWS 9050

Before and after picture of the APC 10 x 3.8 attached as IM003280b.JPG.
Looks a little like the Scimitar prop profile now. Before- the unmodified APC slowfly 10 x 3.8 has a red hub. Actual diameter dropped to
9.87" with the cutting.

The 9050 DD data is for comparison of my setup to that of Dr. Kiwi.
I am obviously drawing 25% less amps than Dr. Kiwi.
That may be due to my use of JST connectors and/or an ammeter cal difference.

The importance of my data is simply that I was able to drop the wattage of my Blue Wonder "just so" from 90 to 80 watts, which is much more reasonable for a 7.6oz Hobby Lobby Yak foamie. Before this change, I had trouble with indoor hovering (ceiling limits vertical bailout...Continue Reading