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Is a KV950 brushless more powerful than 480 brush

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Is a KV950 brushless more powerful than 480 brush

Old 02-07-2007, 01:25 AM
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lt1956
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Default Is a KV950 brushless more powerful than 480 brush

Hello,

I am new at alot of this and was wondering what the performance difference would be between a KV950 Outrunner Brushless against a hopup 480 Brush can Motor? Which one would give more power?

Sorry for the simple question but it will Help alot if someone can help me on this.

Thanks
Old 02-07-2007, 07:20 AM
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B.L.E.
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Default RE: Is a KV950 brushless more powerful than 480 brush

The kV rating of a motor is not a measure of how much power it can make but simply a measure of what RPM the motor delivers its power at. When 1 volt is applied to a 950 kV motor, the shaft will spin approximately 950 rpm when the amps are zero. Spin the motor faster than that and the motor becomes a brake and the amps go negative, recharging the battery. Kv x volts = approximately the no load (shaft run without a prop) rpm of the motor.

The power a motor can make is found by looking at the maximum amps the motor can safely be loaded to. Usually you will see a continuous rating and a somewhat higher burst rating.
Old 02-07-2007, 10:26 AM
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lt1956
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Default RE: Is a KV950 brushless more powerful than 480 brush

I heard outrunner motors have more kick that regular Brushless. I was just curious on average if the brushless I mentioned would be better than a can 480 brush motor
Old 02-07-2007, 02:57 PM
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Default RE: Is a KV950 brushless more powerful than 480 brush

.
The power a motor can make is found by looking at the maximum amps the motor can safely be loaded to. Usually you will see a continuous rating and a somewhat higher burst rating.
Just asking for clarification here because I too am just starting to understand power ratings on e-motors. Please correct me where I am wrong: There is thrust power and speed power much like torque and horsepower on a car, thrust power will operate a bigger and/or higher pitch prop to get a plane up an going quickly at low rpm. Speed power is just high rpm and will get a plane moving fast at level flight. The rated power is determined by the amount of amps at a particular voltage, for example a 400 7.2v brushed motor pulling 5A at 7v will run the same rpm but have more thrust if pulling 5A at 10v. Conversely, 10A at 7v will be faster than 5A at 7v. So, 5A at 10v will have more thrust and less rpm than 10A at 7v. (Numbers were inserted just for analysis and of course gearing and prop is assumed constant here).

Feel free to let me know how close I am, to really understand power comparisons you have to run some figures yourself with the specs given for each motor.
Old 02-07-2007, 11:01 PM
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Dr Kiwi
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Default RE: Is a KV950 brushless more powerful than 480 brush

BeFlyin,

I think there is a flaw in the argument. Just to use your 7.2v 400 motor as an example: say it pulls 5A @ 7v - and spins a certain prop at certain rpm. To get it to pull only 5A @ 10v one would have to reduce the prop size considerably - the smaller prop would spin faster (because rpm is related directly to Kv x v), and would probably generate more thrust (despite its smaller diameter) because you are now pushing more power through it (50W rather than 35W). Getting the motor to draw 10A @ 7v would require a larger prop (to load the motor more) and it would not spin particularly fast (Kv x v again). To have the motor only draw 5A @ 10v means a reduction in prop size again - this prop will spin a lot faster (Kv x v again) - but thrust will be lower because of the smaller diameter and the lower power (50W versus 70W).

Does your brain hurt, now!



400 7.2v brushed motor pulling 5A at 7v will run the same rpm but have more thrust if pulling 5A at 10v. Conversely, 10A at 7v will be faster than 5A at 7v. So, 5A at 10v will have more thrust and less rpm than 10A at 7v.
Old 02-08-2007, 02:48 AM
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lt1956
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Default RE: Is a KV950 brushless more powerful than 480 brush

Well that answers my question. lol No simple answers I guess?
Old 02-08-2007, 07:03 AM
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Default RE: Is a KV950 brushless more powerful than 480 brush


ORIGINAL: lt1956

Well that answers my question. lol No simple answers I guess?
The original question: A good outrunner is usually going to outperform a brushed 480 - it will be lighter than a geared 480, it will be more efficient than a geared 480, it will be quieter than a geared 480, it will be maintenance free and last a lot longer than a geared 480.

If you need to run about a 9-10" prop on 3s a 950Kv outrunner will do well. If you need a different prop size or input voltage - you need to change your motor for one of different Kv [the 480 is a bit more versatile since you can change gear ratios]. But you can also gear an outrunner if need be (Justgofly has several high Kv outrunners which do well in gearboxes)!
Old 02-09-2007, 01:24 AM
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lt1956
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Default RE: Is a KV950 brushless more powerful than 480 brush

Thanks, That helped alot. I ordered a Phoenix 2000 plane on Ebay, and it had the motor I mentioned among some other things. I figured it was the best deal to quality in the beginner electric series. T-hawk was my other choice but lost out due to the 27mhz transmitter and 380 can bruch motor, the upgrade to the 480 was another $13

Over all the Phoenix was $155 with shipping and the T-hawk was $180 with shipping. Both use ABS Fus, and 2 sets of wings. The only difference is T-hawk comes with 3 props, and 2 tails and batteries. The Phoenic 2000 comes with a 72 mhz 4chan Transmitter and 6 channel rec.


P.S. Does having more effeciency on the motor mean MORE flight TIME?
Old 02-13-2007, 09:23 PM
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Dr Kiwi
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Default RE: Is a KV950 brushless more powerful than 480 brush


P.S. Does having more effeciency on the motor mean MORE flight TIME?
All things being equal, it should - your motor will convert more of the battery's power into useful "work", and less into waste heat.

Of course, it depends on whether your motor is drawing exactly the same amps as the "inefficient motor" did. If your replacement is drawing more, you may get the benefit of higher power and thus better flights - not necessarily longer ones!
Old 02-15-2007, 10:25 PM
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Default RE: Is a KV950 brushless more powerful than 480 brush


[quote]ORIGINAL: Dr Kiwi


ORIGINAL: lt1956


If you need to run about a 9-10" prop on 3s a 950Kv outrunner will do well. If you need a different prop size or input voltage - you need to change your motor for one of different Kv [the 480 is a bit more versatile since you can change gear ratios]. But you can also gear an outrunner if need be (Justgofly has several high Kv outrunners which do well in gearboxes)!

I'm new to electrics and am trying this out for my 1st attempt with an outrunner brushless. I got a good deal on a 3500KV outrunner and put a 3:1 gearbox on it with a 9 x 7 prop. I haven't flown it nor do I own a watt meter but at WOT the plane wants to fly out of my hand. I have no intention of running this setup at WOT for the duration of the flight but it will be fun to have the thrust available when needed. I have no idea what my flight times will be like witha 2100mah LiPo setup but with conservative throttle use I hope to get 15 minutes out of it. By the way, the plane weighs about 610g with the battery. Any comments on this setup?

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