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Posted by mejmea | Nov 17, 2015 @ 10:17 PM | 890 Views
In case it is useful or interesting to anyone, below is some performance data I took a few weeks ago related to using different pinions and propellers with the standard 1S UMX gearbox, the BLH3327 motor, an XP-7A esc, and an Eflite 150mAh 45C battery

Test notes:
- I used a UMX P-40 and a UMX P-51 (V1) as the test-beds. Ideally it might have been best to use just one aircraft to eliminate variability in drive train but it was easier this way and I don't think it really influenced the results.
- Each test was run at WOT until LVC was reached. The results shown below are for one battery. I ran a parallel set of tests with a second battery. The second battery turned out to be weaker than the first. As a result they simply confuse the overall picture so I didn't include them in the graphs below. The trends between different pinions and props were similar between the two batteries however.
- Prop RPM was measured with a standard optical/visible light tach
- Thrust was measured by hooking the tailwheel of the aircraft to a small load cell and letting the plane pull against the cell while resting on its mains.
- RPM and thrust were not measured simultaneously because my set up didn't allow that to be easily done. Thus the graph where thrust is plotted as a function of RPM is the compilation of data from separate runs. Not ideal but...
- My personal preference is to use a scale looking prop as opposed to going for the absolute best performance. Hence I...Continue Reading