http://www.hobbypartz.com/alpha-480--1020kv--outrunner-brushless-motor.html
(Continuous Current: 22A, Burst: 28A, 275W)
Plane:
http://www.nitroplanes.com/projet-003-rq11.html
Battery Candidates:
1 - http://www.hobbypartz.com/77p-sl3000-3s1p-30c-3333.html
2 - http://www.hobbypartz.com/77p-sl4000-3s1p-20c-3333.html
3 - http://www.hobbypartz.com/77p-sl5000-3s1p-30c-3333.html
4 - [Any other you might recommend]
The ideal combination would provide enough power to the motor and allow for 30min or more of flight. From what I read and seen, the 1st battery above seems to be the best. But I'm somewhat confused as to the flight time I'd get out of it. I'm thinking that during take off, the motor would require the full 28A of current and during flight it would fly at half throttle, which would probably be around 15A.
The formula I've found for calculating the battery discharge current is:
Battery 1: (3000mAH x 30C)/1000 = 90A <-- the battery would be capable of providing 90A, is this correct?
Battery 2: (4000mAH x 20C)/1000 = 80A <--- 80A, correct?
Battery 3: (5000mAH x 30C)/1000 = 150A <--- 150A, correct?
Formula for flight time:
Battery 1: (3000mAH/15000ma) x 60 = 12min flight time <--- correct?
Battery 2: (4000mAH/15000ma) x 60 = 16min flight time <--- correct?
Battery 3: (5000maH/15000ma) x 60 = 20min flight time <--- correct?
So this seems a bit weird to me. Isn't there any battery that could provide the ideal, say, 30A of current instead of the high currents above (90A, 80A, 150A) and last for more than the flight times I've calculated above?
Additionally, if I only need 30A at max, would the battery then take the "left over" current and somehow provide a longer flight time? In other words, if I fly slow and only use up 15A on a continuous basis would I get a longer flight time than if I fly using 20A+?
Also, does anyone own the Projet RQ-11 Raven and would be willing to let me know their complete set up?
Thanks!
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Replies
The 480 setup will be nice for this plane. A turnigy 35-36 1100kv would be even nicer.
The battery will last as long as the mah capacity relative to amps drawn. A 3000 mah or 3 amp hour battery with a motor drawing 3A would last 1 hour, 6a would be 30 minutes, 12a would be 15 minutes. How many amps you use depends on the plane, throttle management, and prop size. You really do not need a 30c or even 20c battery if you are going to use the large capacity battery that you stated, but because they are cheaper I would go with the 20c.
Also, having a battery that will deliver 80a and a motor that only needs at the most 30a really does not effect flight time. It just means you could power a motor rated at 80a max.
You should also be thinking about what prop to use as this is just as important as the battery. More efficient prop = longer flight times.
I am running hitec 81 servos, eflite park 480 motor, apc 9x7.5e prop, castle thunderbird 54 esc, turnigy 2200 battery, arora 9 radio. needed to put battery in very front with a 1300 lipo for cg but this is without fpv gear. plenty of cooling for electronis never got warm
over all i like wish it slowed down a little better and had a better glide, needs a bit more wing. flew well in a good breez. added a tail skid to protect elevator linkage.
Also, I am thinking of getting this propeller:
http://www.hobbypartz.com/60p-dyp-1003-propeller.html
(It's a 9*5 prop).