MagLev C [Trial]

_HenryHscioly_
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Re: MagLev C [Trial]

Postby _HenryHscioly_ » August 17th, 2012, 8:05 pm

I see a bunch of brushless motors on hobbyking.com, but there is only one brushed motor that runs at 4 volts.
Where can I find brushed motors that can be used for maglev at?

Does using only one motor+prop create significant spinning or leaning of the maglev opposite to the prop's rotation?

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Re: MagLev C [Trial]

Postby chalker » August 17th, 2012, 8:15 pm

It's still a couple weeks before the printed manuals come out, but I'll save everyone the trouble and expense by letting you know the rules will explicitly prohibit brushless motors and integrated circuits of any kind... so stick to the basic brushed motors.

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Re: MagLev C [Trial]

Postby mrsteven » August 17th, 2012, 8:25 pm

chalker wrote:It's still a couple weeks before the printed manuals come out, but I'll save everyone the trouble and expense by letting you know the rules will explicitly prohibit brushless motors and integrated circuits of any kind... so stick to the basic brushed motors.

gahhhh
Time to return some electronics...

So I can't even hook a brushed motor up to a receiver to make starting easier with a remote control? :(
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Re: MagLev C [Trial]

Postby retired1 » August 17th, 2012, 8:45 pm

mrsteven wrote:It is indeed pricy. The ESC you will need to run a brushless will run you the same if not more than the actual motor, then a reciever and transmitter combo is 100 easily and battery pack bc by the time youre in it that much money get a nice battery along with it.
Id say unless this is your specialty event like it is for me this year dont even go this route its really cost prohibitive. Im in it easily 270 for parts
I think most peoPle outside of NY where its been a trial for several years will use brushed. Easier and insanely more reasonably priced.


What is an ESC? Why would you need a transmitter and a receiver for mag lev? IF you do lots of research, there are some affordable brushless motors. Weight is a major difference between the two, but that should not be a biggie if MagLev has a minimum weight. If you go with the plain 9V battery, you might want to take a look at the available mah of LiPoly. They last forever on a charge, but will not provide any where near the amperage draw that an alkaline or a NiMH one will. In short, the battery does not have to be exotic. I found a cheap battery charger for NiMH that works nicely.

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Re: MagLev C [Trial]

Postby mrsteven » August 17th, 2012, 9:01 pm

retired1 wrote:
mrsteven wrote:It is indeed pricy. The ESC you will need to run a brushless will run you the same if not more than the actual motor, then a reciever and transmitter combo is 100 easily and battery pack bc by the time youre in it that much money get a nice battery along with it.
Id say unless this is your specialty event like it is for me this year dont even go this route its really cost prohibitive. Im in it easily 270 for parts
I think most peoPle outside of NY where its been a trial for several years will use brushed. Easier and insanely more reasonably priced.


What is an ESC? Why would you need a transmitter and a receiver for mag lev? IF you do lots of research, there are some affordable brushless motors. Weight is a major difference between the two, but that should not be a biggie if MagLev has a minimum weight. If you go with the plain 9V battery, you might want to take a look at the available mah of LiPoly. They last forever on a charge, but will not provide any where near the amperage draw that an alkaline or a NiMH one will. In short, the battery does not have to be exotic. I found a cheap battery charger for NiMH that works nicely.

ESC, Electronic Speed Controller.
Have you held a brushless motor? They have 3 wires leading out of them, this is R/C stuff, the 3 wires plug into the ESC to reduce them into 2 wires that can do directly onto a battery pack. The ESC is needed because of how a brushless motor functions needing integrated electronics (which chalker said is against the rules this year anyway) to switch the 3rd lead from positive to negative and some other electrical stuff one could look up on a google search.
To use and ESC itself, you have to have a mechanism to issue commands to the ESC, that is the receiver. For maglev, you really only want full throttle but the alternative is too cumbersome and easier just to use a transmitter than to rig the ESC to 'think' a receiver is connected and then you're voiding warantees and really just stuff that doesn't always work.
The BL motors themselves are pretty cheap, 20-30. If you want a nice one like the one I was playing with, closer to 50. The ESC is about the same price, I used a 10A E-flite ESC for my models. I think it was 40. Then battery packs, I won't discuss that in detail since my system is still functional even without use of the BL motors. And then transmitter receiver I used one a friend let me borrow, but the cheapest set you're looking at 100 retail.
I have done my research and created several extremely well functioning models over the summer using this.

BL motors are expensive. Not them, themselves but the stuff you need to go with it. if you don't do you're research before hand and think you can plug it directly into a battery and expect premium results you have a lot of costs that weren't identified.
This is my rant...

EDIT: someone asked about BL motors running on 9 volts, you wouldnt need that much overkill anyways. Less voltage you could get great results. Look into Kv and the relationship you want with torque and RPM. Anything running 9 volts will be REALLY too heavy to be good. You have to do the math (or some people guess and check I guess..) for the needed propulsion, with blades, and weight distribution, how much your magnets can keep up in a fixed point etc.
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_HenryHscioly_
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Re: MagLev C [Trial]

Postby _HenryHscioly_ » August 17th, 2012, 10:51 pm

How does a propeller affect or is affected by a battery + motor?
So, the motor's rpm is proportional to the volts,...then propeller is attached
and i'm lost at the topic of current/loads
could someone please explain how this works?

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Re: MagLev C [Trial]

Postby iwonder » August 18th, 2012, 2:30 am

retired1 wrote:
mrsteven wrote:It is indeed pricy. The ESC you will need to run a brushless will run you the same if not more than the actual motor, then a reciever and transmitter combo is 100 easily and battery pack bc by the time youre in it that much money get a nice battery along with it.
Id say unless this is your specialty event like it is for me this year dont even go this route its really cost prohibitive. Im in it easily 270 for parts
I think most peoPle outside of NY where its been a trial for several years will use brushed. Easier and insanely more reasonably priced.


What is an ESC? Why would you need a transmitter and a receiver for mag lev? IF you do lots of research, there are some affordable brushless motors. Weight is a major difference between the two, but that should not be a biggie if MagLev has a minimum weight. If you go with the plain 9V battery, you might want to take a look at the available mah of LiPoly. They last forever on a charge, but will not provide any where near the amperage draw that an alkaline or a NiMH one will. In short, the battery does not have to be exotic. I found a cheap battery charger for NiMH that works nicely.


(for the record, mAh is a unit, we generally use capacity to reference what you're getting at)
As for the batteries, LiPo batteries can provide insane discharge rates(upwards of 10C, so if the battery is rated for 2Ah(1C), it could provide up to 20A until it discharges) this is due to their inherently low internal series resistance, whereas most other common battery types can't provide that much current, and that's why airplanes and presumably maglevs use LiPo, it can provide a large burst of current(which equates to torque at the motor) however this comes at the cost of run time, you can't simply say that a specific chemistry can ''run forever on a charge' because it depends on what kind of current draw you have and the ratings of the battery. Lastly, even if you had a brushless motor, the Electronic Speed Control(motor drive, basically) is expensive for the motors, because of the multiphase AC generation and commutative of the motor that goes on behind the secnes.

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Re: MagLev C [Trial]

Postby jander14indoor » August 18th, 2012, 3:48 am

_HenryHscioly_ wrote:How does a propeller affect or is affected by a battery + motor?
So, the motor's rpm is proportional to the volts,...then propeller is attached
and i'm lost at the topic of current/loads
could someone please explain how this works?


Same as Wright Stuff or Helicopters, power source must be matched to propeller characteristics for efficient power use. Yes the measures and output curves are different for electric vs rubber power, but the principles are the same. There is MUCH data about this developed for electric RC airplanes where efficient use of battery power is critical. I'm not an expert so don't know if there are web resources (though I expect there are) but RC model flying magazines regularly carry articles where they review electric motors and batteries where they characterize and measure the properties of propellers and electric motors.

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Re: MagLev C [Trial]

Postby mrsteven » August 18th, 2012, 7:08 am

jander14indoor wrote:
_HenryHscioly_ wrote:How does a propeller affect or is affected by a battery + motor?
So, the motor's rpm is proportional to the volts,...then propeller is attached
and i'm lost at the topic of current/loads
could someone please explain how this works?


Same as Wright Stuff or Helicopters, power source must be matched to propeller characteristics for efficient power use. Yes the measures and output curves are different for electric vs rubber power, but the principles are the same. There is MUCH data about this developed for electric RC airplanes where efficient use of battery power is critical. I'm not an expert so don't know if there are web resources (though I expect there are) but RC model flying magazines regularly carry articles where they review electric motors and batteries where they characterize and measure the properties of propellers and electric motors.

Jeff Anderson
Livonia, MI

I wouldnt even go that far. Over the summer i effectively learned a ton about this on my quest to find the right motor/battery/props so just by some simply google searches you can find base ideas and formula to assist you in this. R/c planes are popular and in fact, the brushless set up i spoke about before IS essentially the 'guts' of an r/c plane. Using plane motors, esc and batteries. Learn about batteries and all the technical spec and what they mean in application, then with the motor there are formulas you can develop or find that will relate it for you and others to find the load changes on the discharge rate, although easiest of themall after you get a motor is to get the prop and run it on a power supply and get experimental values for the current drawn to determine the correct needs of the battery
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