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Old Mar 10, 2013, 10:08 AM
NoT iNtElLiGeNt
India, Andhra Pradesh, Guntur
Joined Jan 2011
126 Posts
i am thinking to use 10 A ESC for donkey motor.....

http://hobbysea.com/products.php?34&...c65aaea1c44326

what do u say


i could not get below 10 Amps in india
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Old Mar 10, 2013, 10:52 AM
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Quote:
Originally Posted by jyothibasu1k View Post
i am thinking to use 10 A ESC for donkey motor.....

http://hobbysea.com/products.php?34&...c65aaea1c44326

what do u say


i could not get below 10 Amps in india
It might be OK. It depends on what you are building. The motor and esc may also be too small if it is going on the same craft you have already built.
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Old Mar 10, 2013, 01:07 PM
NoT iNtElLiGeNt
India, Andhra Pradesh, Guntur
Joined Jan 2011
126 Posts
Quote:
Originally Posted by leadfeather View Post
It might be OK. It depends on what you are building. The motor and esc may also be too small if it is going on the same craft you have already built.


" The motor and esc may also be too small if it is going on the same craft you have already built. "

i did not understand this sentence wat do u mean by it ?
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Old Mar 10, 2013, 01:40 PM
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Quote:
Originally Posted by jyothibasu1k View Post
" The motor and esc may also be too small if it is going on the same craft you have already built. "

i did not understand this sentence wat do u mean by it ?
The craft you have built and you have shown on this thread may be too heavy for this motor and esc to lift.


Since you haven't stated that you are building a new craft, I can only assume you are interested in buying these motors and esc's to replace the motors and esc's you have already used??
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Old Mar 10, 2013, 07:56 PM
NoT iNtElLiGeNt
India, Andhra Pradesh, Guntur
Joined Jan 2011
126 Posts
are u sure that a 1500kv motor can't lift, a craft of weighing below 800 grams.

last video i have posted in thread with flybar is made of foam material and it is nearer to 1 kg. in which each motor is weighing 200 gm so now i am changing the motor's. 40 g each.

200 +200 = 400
40+40 = 80
reduction = 320grams

totally= 1000-320 = 680 grams.

can the 1500 kv or 1700 kn motor lift 700 grams weight ?





Quote:
Originally Posted by leadfeather View Post
The craft you have built and you have shown on this thread may be too heavy for this motor and esc to lift.


Since you haven't stated that you are building a new craft, I can only assume you are interested in buying these motors and esc's to replace the motors and esc's you have already used??
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Old Mar 10, 2013, 09:25 PM
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Quote:
Originally Posted by jyothibasu1k View Post
are u sure that a 1500kv motor can't lift, a craft of weighing below 800 grams.

last video i have posted in thread with flybar is made of foam material and it is nearer to 1 kg. in which each motor is weighing 200 gm so now i am changing the motor's. 40 g each.

200 +200 = 400
40+40 = 80
reduction = 320grams

totally= 1000-320 = 680 grams.

can the 1500 kv or 1700 kn motor lift 700 grams weight ?
kV is a measure of motor speed not motor power. A 1550 kV motor will spin at 1550 x volts when there is no load (no prop). Example: at 10V, the unloaded motor would spin at 1550 x 10 = 15,500 rpm.

Here is the motor data for the 1550 kV Donkey motor from Hobby King.

Specs:
RPM/v: 1550kv
Dimensions: 28 x 17mm
Shaft: 3.0mm
Voltage: 7.4v~11.1v
Weight: 33g
No-load current: 1.0A @ 11.1v
Max Current: 10A
Max Watts: 100W
Mounting Holes: 33mm

Prop Data:
7035 - 7.4v - 3.5A - 180g Thrust
8043 - 7.4v - 6.4A - 285g Thrust
7035 - 11.1v - 6.5A - 370g Thrust

Looks like the best thrust without overloading this motor is about 370 grams and is obtained using a 7035 prop.
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Old Mar 11, 2013, 07:25 AM
NoT iNtElLiGeNt
India, Andhra Pradesh, Guntur
Joined Jan 2011
126 Posts
i have already seen that link

but its 1550kv, i have 1500 kv

more over my college told to submit the report by 15th march

i have only 3 days and still i am unable to get esc's of 12 amps

so i will try my best with those previous turningy motors by reducing the propeller length.


hope god helps me..... i have decided to conclude what ever the result be by 14th ni8.....









Quote:
Originally Posted by leadfeather View Post
kV is a measure of motor speed not motor power. A 1550 kV motor will spin at 1550 x volts when there is no load (no prop). Example: at 10V, the unloaded motor would spin at 1550 x 10 = 15,500 rpm.

Here is the motor data for the 1550 kV Donkey motor from Hobby King.

Specs:
RPM/v: 1550kv
Dimensions: 28 x 17mm
Shaft: 3.0mm
Voltage: 7.4v~11.1v
Weight: 33g
No-load current: 1.0A @ 11.1v
Max Current: 10A
Max Watts: 100W
Mounting Holes: 33mm

Prop Data:
7035 - 7.4v - 3.5A - 180g Thrust
8043 - 7.4v - 6.4A - 285g Thrust
7035 - 11.1v - 6.5A - 370g Thrust

Looks like the best thrust without overloading this motor is about 370 grams and is obtained using a 7035 prop.
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Old Mar 11, 2013, 09:09 PM
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Quote:
Originally Posted by jyothibasu1k View Post
...i have 1500 kv...
I wouldn't go over 7 and a half inches with a 1500 kv motor.



So each blade will be less than 4 inches long.
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Old Mar 11, 2013, 11:21 PM
NoT iNtElLiGeNt
India, Andhra Pradesh, Guntur
Joined Jan 2011
126 Posts
how much should i cut for 1200 and 1300 kv motor's



Quote:
Originally Posted by RCvertt View Post
I wouldn't go over 7 and a half inches with a 1500 kv motor.



So each blade will be less than 4 inches long.
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Old Mar 11, 2013, 11:50 PM
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Quote:
Originally Posted by jyothibasu1k View Post
how much should i cut for 1200 and 1300 kv motor's
F&T is the expert on cutting these. Helicopter blades are wide so if your motor takes 10 inch props. Start with these cut down to 9 inch.

I think 8 inches total length will be best. So each blade would be 4 inches.


Start with 4 and a half inches for each blade. Run up the motor for a few seconds then shut it off. Then touch the motor and ESC to see if they are getting warm. If they get warm then cut off some more of the blade.
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Old Mar 11, 2013, 11:52 PM
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I don't think hot motors would burn your receiver.

Sounds like your receiver can't handle all the servos it is running. External 3 amp BEC would fix that.
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Old Mar 12, 2013, 09:13 AM
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United States, CA, Sunnyvale
Joined Dec 2006
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Or drop your voltage from 3S to 2S and keep the blades as they are now. The math says larger diameter produces more thrust for the same amount of power. What I dont know is the relative efficiency of the motor at the same current, but lower voltage and lower RPM, vs higher voltage and higher RPM.

Cutting blades is irreversable, short of buying new ones.

3S to 2S is a big drop, so it may not have enough power to fly at that point. You can do the math, or you can try it and find out.
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Old Mar 12, 2013, 10:49 AM
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Joined Oct 2004
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Hmm, I think that would have about the same effect as throttling down, and I don't think that taking energy out of the system will help unless is matched with a great reduction in weight. ideally to run an helicopter head you would mechanically gear down the motor, to keep high motor RPM and low torque. But one of the great advantages of electric motors over internal combustion ones is that they can provide torque over a great range of speeds.
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