[cassat]

Ok so the motor is : Hacker A20-20L
RPM is : 1022kV
Suggested prop : 10 x 4.7 slowflyer
Suggested Power : 3S 1350 Lipo

Trouble is on 3S I can only get to half stick, then it feels like its gonna rip the motor out of the plane due to so much pull!! Ha So at 12.5 volts, it would be turning over 12,000 rpm's and esc was quite warm (18A)

So, I tried a Radian prop (think its 9 x 7.5 ) and still pretty wild. So tried a 2S 2500 lipo
With 2S , I get to half stick and then motor rpms limit out and no increase past half throttle. Esc, motor, and lipo remains cool....puzzled....any ideas??

[Cougar429]

One thing I found with specs are most are a bit aggressive with their prop recommendations. Slowflyer props are also high drag if you spin them too fast, meaning your current requirements would be higher. Your dropping the diameter one number may have worked, but I think the pitch increase offset any benefit.

If you have an MA or APC prop in the same pitch range I would think you would get better performance and a cooler ESC at the end.

[cassat]

oops, it appears that the radian prop is 9.75 x 7.5 so I will need to prop down a bit.

[Terry Gauvin]

What current were you pulling on 2S? What is the rating of the ESC? What brand?

[mark_]

Seems strange Dave...how have you been? Haven't seen you around too much lately?

[cassat]

Ha Ha Very Funny Mark the Mountain Man...here every day watching the rain !! Where have you been ???

Terry, I think I was pulling 20 Amps with 3S on a 10 x 4 gws slowfly prop. The esc is
rated at 18 amps.I can increase to a larger esc so thats not a problem . I did run a
similar clone motor in a Trojan with a 10 x 4.7 APC and it was perfect.

[cassat]

Sorry, not sure the amp draw on 2S. The esc is HK brand 18A but not even warm.

[Max]

It is cases like this that I find the use of a data logger like the watts-up or the eagletree to be invaluable.

Without data, its all just a guessing game. By using a data logger, I can instantly see what my volts and Amperage draw is. What interests me specifially is amps. Based on that I can calculate my flight time as well as how close I am to the limits of the ESC.

Once you have a power combination set up, the only variable you have to play with is prop pitch and diameter. Experimenting with different props will help you find the pitch/diameter that works best.

If you dont have a data logger, the other option is to fly your plane for a short period (ie 2 minutes) and then charge your battery with an intelligent charger that will tell you how many millamps were put back into the battery. Then you compute milliamps over the duration of the flight to calculate the amperage being drawn by your power system.

[cassat]

Thanks Max.

The motor definitely does not like 2S so I went back to a 3S Lipo and changed the prop to a lower pitch APC 9 x 5. Ironically the specs call for 3S and a 9 x 5 prop! Ha
So now I just have to change the esc up to 20A and try different props as you say.

[cassat]

Wow, really hard to find a 9 x 5 folding prop in stock ! Hobby King and Horizon are both
out of stock.