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Test av
APC-G 9X5
APC-E 9X4.5
APC-SF 9X47
GWS-R 9X47
Se det lille miniatyrbilde det viser test datane
We had a discussion the other day at the flying field about the prop efficiency and the feeling one gets with different props in flight.
I was advocate for APC-E props that are my reference props when doing lab tests. I have a feeling they are optimal solution for motors turning 5000 to 10000 RPM and besides, they seem to be lighter than glow APC's.
Slow fly props on the other hand are RPM limited to 65000/size (6500 rpm max for 10" for instance) and have undercambered airfoil suitable for low speeds.
But my flying buddy Hrvoje is convinced APC Slow-Fly props give him better throttle response, stronger pull and more authority.
Since my KDA 22-20L powered 33" Extra 300 is not finished yet I cannot prove or deny his findings at the flying field.
Fortunately, here is my test stand ready for all kinds of testing and as KDA22-20L was already bolted on, it was so easy to attach few props and see what will gauges and dials say.
I have on hand no less than 4 different props in 9x5 size and KDA22-20L copes with that load with ease. This is important as slightly different load different props produce won't change motor's efficiency. Besides, time for motor themperature to stabilize won't be to long. Unfortunately, I wasn't able to get 9x5 GWS Direct drive prop for this test as it is currently on backorder at UH.
I have used PC power supply as the current source since it is reasonably stable and doesn't change voltage in time as batteries do. With unloaded 5V rail these cheap power sources provide approx. 11V on 12 rail which perfectly simulates 3 LiPo cells.
Every prop was tested 9 times after 3 minute warmup and results are averaged.
Below you can see results sorted so all the measured parameters can be compared. Please notice pretty huge differences in practicaly all columns.
There is another set of values not imported into the chart and it's prop weight. APC-G weights 17g, APC-E exactly the same (what a surprise!), APC-SF just 8g while GWS-R is a winner with 4g weight. I have added g/w calculated values which I hate seeing declared as "efficiency". There is more than just pure static thrust that adds to total prop efficiency. For instance, GWS-R prop gets highest g/w figure, but APC-SF exceeds it's airflux velocity by a considerable margin.
Please notice that I have exceeded APC-SF prop's allowed rpm limit and this is the kind of use I won't recommend to anyone. So PLEASE DON'T DO THAT! Besides, I believe that GWS-R prop has similar rpm limit (if not even lower due to lighter construction) so my warning should be extended to that prop as well.
You can easily see that higher thrust and/or speed props draw more current so obviously there is no free lunch here.
Dear fellow e-fliers, I'll be glad if you can contribute with your experience here!
Test av
APC-G 9X5
APC-E 9X4.5
APC-SF 9X47
GWS-R 9X47
Se det lille miniatyrbilde det viser test datane
We had a discussion the other day at the flying field about the prop efficiency and the feeling one gets with different props in flight.
I was advocate for APC-E props that are my reference props when doing lab tests. I have a feeling they are optimal solution for motors turning 5000 to 10000 RPM and besides, they seem to be lighter than glow APC's.
Slow fly props on the other hand are RPM limited to 65000/size (6500 rpm max for 10" for instance) and have undercambered airfoil suitable for low speeds.
But my flying buddy Hrvoje is convinced APC Slow-Fly props give him better throttle response, stronger pull and more authority.
Since my KDA 22-20L powered 33" Extra 300 is not finished yet I cannot prove or deny his findings at the flying field.
Fortunately, here is my test stand ready for all kinds of testing and as KDA22-20L was already bolted on, it was so easy to attach few props and see what will gauges and dials say.
I have on hand no less than 4 different props in 9x5 size and KDA22-20L copes with that load with ease. This is important as slightly different load different props produce won't change motor's efficiency. Besides, time for motor themperature to stabilize won't be to long. Unfortunately, I wasn't able to get 9x5 GWS Direct drive prop for this test as it is currently on backorder at UH.
I have used PC power supply as the current source since it is reasonably stable and doesn't change voltage in time as batteries do. With unloaded 5V rail these cheap power sources provide approx. 11V on 12 rail which perfectly simulates 3 LiPo cells.
Every prop was tested 9 times after 3 minute warmup and results are averaged.
Below you can see results sorted so all the measured parameters can be compared. Please notice pretty huge differences in practicaly all columns.
There is another set of values not imported into the chart and it's prop weight. APC-G weights 17g, APC-E exactly the same (what a surprise!), APC-SF just 8g while GWS-R is a winner with 4g weight. I have added g/w calculated values which I hate seeing declared as "efficiency". There is more than just pure static thrust that adds to total prop efficiency. For instance, GWS-R prop gets highest g/w figure, but APC-SF exceeds it's airflux velocity by a considerable margin.
Please notice that I have exceeded APC-SF prop's allowed rpm limit and this is the kind of use I won't recommend to anyone. So PLEASE DON'T DO THAT! Besides, I believe that GWS-R prop has similar rpm limit (if not even lower due to lighter construction) so my warning should be extended to that prop as well.
You can easily see that higher thrust and/or speed props draw more current so obviously there is no free lunch here.
Dear fellow e-fliers, I'll be glad if you can contribute with your experience here!
Attached Files