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Noob question: What is brushless, why is it better?

Old 11-12-2009, 01:03 AM
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moby323
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Default Noob question: What is brushless, why is it better?

I'm pretty new to helis, but I got the fever. Started with an airhog, now I've got a Esky co-axial and will soon move up to honey bee.

Anyways, I've got a noob questions: what does brushless mean in helicopters, and why is it better?

thanks
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Old 11-12-2009, 03:41 AM
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PaperAirplane
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http://electronics.howstuffworks.com...less-motor.htm
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Old 11-12-2009, 04:50 AM
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moby323
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so, in other words, a brushless motor is more efficient and more powerful...
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Old 11-12-2009, 05:01 AM
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Wildflyer
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in a nut shell you got it.

I have heard that a brushed DC motor is only about 25-35% efficient, and that a brushless is 75-90% efficient.

They are referring to how much of the battery power actually is turning the prop.

I have had some powerful brushed motors, but I am amazed at the power of my brushless motors. More power & less drain on the battery, you got to like that.
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Old 11-12-2009, 11:39 AM
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Moxus
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Originally Posted by moby323 View Post
I'm pretty new to helis, but I got the fever. Started with an airhog, now I've got a Esky co-axial and will soon move up to honey bee.

Anyways, I've got a noob questions: what does brushless mean in helicopters, and why is it better?

thanks
on the honeybee:

dont buy it.
my dad bought it, because it was a "3d aerobatic trainer" (honeybee cp).
i bought the belt-cp because it was "fully capable 3d".
in my opinion, the belt-cp is easier to fly than the honeybee.
and the tail system on the honeybee is a total headache (crap gyro).
and changing the gyro isnt that simple either, because the gyro is integrated with both tail speed control AND main motor speed control.

of course you can change all that , but it will quickly cost you more than a brand new belt-cp.
so my tip, just go directly to the belt-cp.
its easier to fly, its bigger, more stabile, and a fully working honeybee with modded gyro will be more expensive than the belt-cp anyway.

of course, you might note that i was talking about the honeybee CP and not the honeybee. but those 2 helis has the same tail rotor system, so it hte headache with the tail is precisely the same i guess.

in general, these small helis is NOT easy to fly, even if they are so called trainers.
a conversion from coaxial to single rotor heli will be a big leap if you got no experience from before.

i flew the hirobo shuttle sxx and got confident with it some years ago.
still, starting to fly again on the belt-cp felt difficult because the chopper is so small, quick and sensitive to controls.
it was like learning to fly all over again, from the most basic hover.
the honeybee is EVEN MORE sensitive, because its smaller.
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Old 11-12-2009, 05:04 PM
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moby323
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Now when you say not to get the the "honeybee" do you mean the fp honeybee v2 or the honey bee king III?

BTW, what is the difference between the honeybee king III and the honey bee cp v2?
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Old 11-12-2009, 08:18 PM
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Moxus
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i mean the honeybee fp and cp v2, since both share the same tail rotor system.
its the tail gyro that is the issue. and since the gyro is heavily integrated to the other control electronics, you may only salvage the stock reciever, and have to buy the rest new to change the gyro.
"the rest" is more specificly: main rotor speed control, tail rotor speed control, and a better gyro.
the gyro alone, for the belt cp, costs about 22 dollar. you will have to give about the same for the speed controls, and then you suddenly find that a WORKING honeybee fp or cp isnt much cheaper than a belt, or a honeybee king.

the honey bee king 3 is a completely different copter altogether, and is more alike the belt, than it is to its smaller name-brother.
i havent tried the honey bee king, but i suppose its on par with the belt.
only difference seems to be that its marginally smaller.
in fact, the belt and the honey bee king shares a lot of the same vital parts, and they got identical rotor heads.

the tail gyro problem in detail:
*if you could be bothered*
the issue seems to be overheating of some electronics within the gyro.
thats my qualified guessing.
it works seamlessly when you take off, but the more you fly, the more you need to hold the rudder stick to the left to make it fly straight.
it gets worse and worse the more you fly, and after a minute or two, you need to hold the rudder stick fully to the left to keep the tail straight!
if you land and let it cool off for some mins, its fine when you take off again.
i have no idea what causes it exactly.
i tested the rudder channel with just putting a servo there instead of the gyro, and the signal is all fine out of the reciever.
the tail rotor motor is also nice and cool when the problem occurs, so its not overheating of the tail motor itself.
so that means, problem exists between reciever and tail rotor motor.
thats only 2 things it could be, gyro and tail speed control.
since those two is the same unit, it doesnt really matter wich one it is.
that gyro/speed control unit needs to go.

Last edited by Moxus; 11-12-2009 at 08:34 PM.
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Old 11-13-2009, 03:01 AM
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Hi Dave,
I just wanted to point out that your figures for brushless efficiency are exactly right (75%-90%) but I believe the numbers for brushed motors are too low.
Bottom line is they'll deliver 50% of the power to the prop, and with the right prop and input voltage, even more. With gearing, much more.
Here's some screen shots of the E-Calc from FMA Direct. I used both 6.0V and 7.2 volt Speed 400's from Graupner, a common example of "Can" motors supplied with many low-priced ARFs.
First I ran it with a 4:1 gear drive, 9" x 6" APC and both 3s 2100 LiPo and 8 cells/1050Mah KAN, then the same batteries with direct-drive and a 6" x 3" APC prop.
Are they as good as brushless? No. And they don't last long, either. But 60%-72.5% efficiency isn't too bad!
Ron
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Old 11-13-2009, 05:12 AM
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You are no doubt right, we were just talking at the hobby shop, and now that I think of it they may have been thinking of the low cost can motors and not some of the better brushed motors.
I have a Astro Cobalt 05, that when matched with a pack of racing nicad batteries, would put out a startling amount of power. BUT now I can have the same amount of power at about 1/3 the weight if that,
Now that I think of it, I may have to try that Cobalt 05, with some large lipoís

I love our new systems, both power and control, we can do so much more now, so easily, that the new comers ( less than 20years ) donít realize how good we have it.

The first electric plane I saw fly, took 200 feet to take off, and the flight lasted about 2 minutes.
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Old 11-13-2009, 05:40 AM
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Originally Posted by Wildflyer View Post
...
The first electric plane I saw fly, took 200 feet to take off, and the flight lasted about 2 minutes.
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