Prop selection advice Hacker A40-10S on 4S1P - RC Groups
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Apr 26, 2012, 01:52 PM
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Prop selection advice Hacker A40-10S on 4S1P


Yes I have a watt meter and Castle Creation data logging but what I don't have is a bunch of props to play with when I get home. I have a 15x7 APC.

I'm not a 3D flyer...yet. I'd like to learn but until then I'm a sport flyer with 3D asperations.

Anyone have a swag as to proper prop selection for a Hacker A40-10S on 4000mah 4S1P battery?

It is about 100 mile RT from home to nearest hobby shop but only 2 miles from where I work. I'm at work today but not again until next Tuesday

I guess I feel like I should get something in case the 15x7 is to much prop.

Any guidance would be appreciated.
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Apr 26, 2012, 07:20 PM
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Dr Kiwi's Avatar
Unless that motor is good for 112A/1600W... then yes, MotoCalc says that a 15x7 would be too much.

Motor: Hacker A40 10S; 880rpm/V; 3.8A no-load; 0.007 Ohms.
Battery: Thunder Power TP5200 (G4 ProRace 50C) (50C); 4 cells; 5200mAh @ 3.7V; 0.001 Ohms/cell.
Speed Control: Castle Creations Phoenix 60; 0.0012 Ohms; High rate.
Drive System: Direct; 15x7 (Pconst=1.17; Tconst=1) direct drive.
Airframe: Anything you want.
Conditions: 700ft above Sea Level, 29.92inHg, 68F
Motor Amps = 112.7
Motor Volts = 14.2
Input (W) = 1602.1
Prop RPM = 8965
Thrust (oz) = 187.6
PSpd (mph) = 59.4

Since the original Hacker A40-010S is rated for 900W/40A max, and even the new V2 is rated for only 1000W/50A max... it will be toast with a 15x7! On 4s 10x7 seems to be about it as far as amp draw goes... if you want to approach 1000W and yet keep amp draw between 40A-50A... you need about 6s and an even smaller prop.
Last edited by Dr Kiwi; Apr 26, 2012 at 07:31 PM.
Apr 26, 2012, 08:03 PM
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scirocco's Avatar
Assuming it's the V2, it will remain within its limits on 4S with 13" up to 13x10, or 14" up to 14x7.

I'd pick up a 13x6.5 and a 13x8 if you're looking for around 650-750 W in

12x6 > 520W, 12x8 > 620W, 12x10 > 715W.

Just don't try the 15x7 on 4S. It would be a reasonable slow speed/3D choice on 3S for about 50A/500W, but you'd need biggish packs to deliver the 50 odd amps.

Dead easy to what if in ecalc - the motor is listed

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