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Power Systems Talk about motors, ESC speed controllers, gear drives, propellers, power system simulators and all power system related topics

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Old 04-09-2013, 12:35 AM   #1
MThemadhatter
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Default Seagul PC-9 120 Power set up

I am thinking about putting together one of these and making it electric

http://www.seagullmodels.com/ProductDetail.asp?id=89

I fly off a grass patch so reserve power is always good.

I am looking at an 8cell set up as another model I am building atm will use 2 x4500mAh 4s batteries and I could use these to make an 8s 4500mAh pack for the PC-9. Do you think that would give me ~8min of duration ?

I have looked at 6cell set ups but it seems that the current draw is quite high for these. I am not sure what kv of motor to go for though or which make. I have looked at this set up as I have some of these Emax motors and they seem more efficient than other cheaper motors

Emax GT5325/09 325Kv http://www.emaxmodel.com/views.asp?hw_id=32
Emax 100amp esc http://www.emaxmodel.com/views.asp?hw_id=46

With a 16x10 prop this should give me 1900W static and about 70mph level.

What do you guys think ? Does anyone have one of these and what is your set up ?
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Old 04-09-2013, 01:42 AM   #2
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E-Flite Power 160 or similar. (lists as a 10S recommended... can be pushed to 12S with appropriately smaller dia prop)

Good pick on the 100 amp ESC

10S or 12S LiPo.

8S is a bit marginal for 120 glow equiv power. You'd be pulling high amps. Its more efficient to go up in volts than amps.
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Old 04-09-2013, 11:01 AM   #3
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Thanks for that,

Using motocalc that would drop the current down from ~70A at WOT to about ~55A on a 16x10 with 2Kw under load. This would would be about 0.38Kg heavier I was trying to keep the weight down. The above gives about 15lb of static thrust, I would prefer speed over prop hanging lol

Are their any good alternatives to the Eflite motor, its a little out side of my budget.

I have looked at these

http://www.emaxmodel.com/views.asp?hw_id=33

http://www.hobbyking.com/hobbyking/s...ner_Motor.html

The jump to 5cell is only about 25 more expensive so I can cope with that

I was aiming for 175W a pound
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Old 04-09-2013, 06:37 PM   #4
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Default

Originally Posted by MThemadhatter View Post
Thanks for that,

Using motocalc that would drop the current down from ~70A at WOT to about ~55A on a 16x10 with 2Kw under load. This would would be about 0.38Kg heavier I was trying to keep the weight down. The above gives about 15lb of static thrust, I would prefer speed over prop hanging lol

Are their any good alternatives to the Eflite motor, its a little out side of my budget.

I have looked at these

http://www.emaxmodel.com/views.asp?hw_id=33

http://www.hobbyking.com/hobbyking/s...ner_Motor.html

The jump to 5cell is only about 25 more expensive so I can cope with that

I was aiming for 175W a pound
Yup

Your 175 watts per pound of airplane is quite feasible for a big model airplane, but it will be expensive.

IMHO, for giant scale models, your power system is not the place to go cheap. For my two giant scale models, they use the Hacker A60-16M, and A60-5S motors. These motors work very well, but they are about twice the cost of some of the other motors.

The A60-16M motor is installed in a Giant Scale Big Stick, powered by a 12S2P A123 battery pack. The motor turns a 19X12 APC-E wide blade prop at 6700 RPM on the ground, and unloads to 7200 RPM in the air, per the Castle Creations ICE data logging functions.

This power system hauls that model straight up in the air, out of sight. It's running at about 160 watts per pound.

The specs for the Hobby King motor and the Hacker motor are nearly identical. Perhaps other wattflyer readers can respond to the quality and reliability of the Hobby King Turnigy Rotomax 1.60 motor. Along with this, how accurate are the Hobby King motor's specifications? This Turnigy motor is 1/2 the cost of the Hacker motor, a significant savings. On the other hand, the specs of my eight Hacker motors are very close to their published specifications.

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Old 04-09-2013, 11:30 PM   #5
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Very true, I am more confident about the E-Max motors. I have 2 already and both are smooth and efficient drawing less current for a given rpm than other motors I have tested.
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