Nov
19
19
Prop Better than the EDF 90mm
11.1 V Lipo, 2200mah, 3C, 880 Grams thrust, Turnigy L2210-1650 Commenti disabilitati su Prop Better than the EDF 90mm
Tried to fly the wee jet at Akaroa today and it was dismal and under powered :(
Calculation Spread Sheet
So taking some advise from DIY Drones I did some more testing and have found a sweet spot with some props I have laying around.
Turnigy L2210-1650 Bell Style Motor
Spec.
Kv: 1650 rpm/vVoltage:7.4~11.1v (2~3s)No load Current: 1.3AMax Current: 22AMax Power: 250W
Shaft Size : 3mm
Shaft Length: 28mm
Dimension: 28mm x 17mm
Thrust: 520g Weight: 50g
My results with a 7 X 5 three blade are as follows on a 3C
23.6 Amps
11020 RPM
880 Grams Thrust !
240 Watts
That's on a 2200mAh 3C and a Turnigy AE-30A Brushless ESC
I have read that the following formula calculates approximately the max speed of the model
Plane_KMH = Prop_Pitch_Inches X RPM / 800
Given this is correct?
5 X 11020 / 800 = 68.875Kmh
Should give a minimum duration of 5.6 minutes
Using a 4C on a 5 X 5 Three Blade Prop
Next test will be with a 4C and smaller prop, optimized for 250 Watts should be around 16 amps
Tested a 5 X 5 three blade
Rhino 1550mAh 3S 11.1v 30C Lipoly Pack
Thrust: 770 Grams
Watts: 238 Watts
Amps 16.4 Amps
RPM: 14,200 RPM
Plane speed 5 X 14200 / 800 = 88.75 Kmh
Should give a minimum duration of 5.8 minutes
I think either of these options will do the job, the plane weighs 685 grams with a 2200mAh 3C on board, wing loading 18 oz/ft²
Conclusion
Given the 4C is no more efficient and the duration advantage in negligible, and the 4C battery is only 7 Grams lighter, I favor the 3C on the bigger prop. There is a theoretical 20Kmh speed advantage for the 4C but the 3C is plenty fast enough.
The Plane
A mass of 500 or 750 grams give a wing loading's of 13 oz/ft² and 19 oz/ft² respectively
Wing area 1.3855 ft²