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Old Jul 27, 2011, 11:13 PM
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Indianapolis, IN
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I appreciate your help Prof. Need to sit down and take a closer look although I'm not sure I even know what the outrunner bell is. I am curious what motor and esc you are using? I look at the videos posted in this forum and my setup (Stock setup) seems ridiculously underpowered.
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Old Jul 27, 2011, 11:20 PM
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Canton, Michigan USA
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Originally Posted by jbartley1130 View Post
I appreciate your help Prof. Need to sit down and take a closer look although I'm not sure I even know what the outrunner bell is. I am curious what motor and esc you are using? I look at the videos posted in this forum and my setup (Stock setup) seems ridiculously underpowered.
The outrunner bell is the outside of the motor that turns. I run a gold Turnigy 35-36C and 60 amp ESC because I had it in stock. The shiny bell is like a well cleaned gymansium floor. The motor wires on the Turnigy are like a sticky pair of gym shoes. Put together they can really stick. The 3 motor wires have to be routed from the front of the motor to the inside and they are very close to outside surface of the shiny rotating outrunner bell.
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Old Jul 27, 2011, 11:23 PM
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Indianapolis, IN
Joined Sep 2010
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Gotcha!!! Thanks, you solved my problem!!
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Old Jul 27, 2011, 11:32 PM
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Canton, Michigan USA
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Gotcha!!! Thanks, you solved my problem!!
JB,
Great! I finally just tie wrapped them to the inside of the fuselage. I put a small piece of thin ply on the outside to allow me to pull the tie wrap tight against the wires without pulling through the foam exterior.

Bill
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Old Jul 28, 2011, 12:40 AM
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Anchorage, Alaska
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Originally Posted by jbartley1130 View Post

Also, how do you balance the prop? I hear you guys talking about this from time to time.

Thanks guys,

John
My reply is not intended as a smartas$ response, most of us know how to balance a prop and have the tool to do so. John, buy a prop balancing tool. There is several out there, they average about $20.00 and they come with instructions. The idea is to center the prop on a shaft, set it in the balance tool and determine the heavy end of the prop, then remove weight from that end until the prop is balanced. The process is called "Dynamic Balancing."
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Old Jul 28, 2011, 09:55 AM
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United States, UT, Salt Lake City
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Originally Posted by Taildragger55 View Post
My reply is not intended as a smartas$ response, most of us know how to balance a prop and have the tool to do so. John, buy a prop balancing tool. There is several out there, they average about $20.00 and they come with instructions. The idea is to center the prop on a shaft, set it in the balance tool and determine the heavy end of the prop, then remove weight from that end until the prop is balanced. The process is called "Dynamic Balancing."
Not to be picky but that is static balancing.
dynamic balancing is done with the prop in motion
Anyway - a real problem withsome props is that the imbalance is NOT along the prop length axis
This can be found using a very accurate balance ,which will sho that one blade always hangs at an angle
not vertically or random stopped position.
In these cases the out of balance point is vertically oriented -

for example if the blade always stops at -say 10:00 and 4:00 o clock-- the weight which is causing this ,is at 6:00 o clock- or in the hub
Try tiny dabs of clay and add at this point -till you get random stopped blade positions

It can be tricky but it's worth learning. Final weights can be another trick -especially if the real issue is a prop hub with a void in it or a hole off center or horizontal alignment. The finished product should have perfect blade tracking and random prop stopping on a frictionless balancer.
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Old Jul 28, 2011, 10:24 AM
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Joined Jul 2011
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Originally Posted by jbartley1130 View Post
I need some help. This has never happened to me before. When I hit the throttle, I hear a weird noise (almost like a "stripping" sound from the motor) and the prop simply stops after a second. Then, I'll try the throttle again and there is no problem. This has even happened in flight if cut the throttle (to glide or what not). It almost caused a pretty bad crash, but I was high enough, and for some reason, the motor decided to work again after a couple attempts at powering the plane up. I'm at a loss.

Also, how do you balance the prop? I hear you guys talking about this from time to time.

Thanks guys,

John
Although I've not had this screeching noise on my Funcub I have had it on other models and it is caused by a slight incorrectness in the esc timing - close and re open the throttle and it is usually ok. This seems to mostly happen when motor and speed controller are bought seperately and not as a pair and as far as I can tell it isn't something to worry too much about unless your a 3d flyer.

Alan
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Old Jul 28, 2011, 11:19 AM
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United States, WA, Seattle
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This seems to mostly happen when motor and speed controller are bought seperately and not as a pair and as far as I can tell it isn't something to worry too much about unless your a 3d flyer.

Alan
It's a sign that the motor may be over propped (very common problem), or the timing is off. Usually advancing the timing will fix it IF the prop size is OK. It is NOT good to ignore the problem. It does have the potential for damaging the motor. It's like of like a 'backfire' in a car-not good.
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Old Jul 28, 2011, 11:28 AM
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Australia, VIC, Melbourne
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Originally Posted by richard hanson View Post
Not to be picky but that is static balancing.
dynamic balancing is done with the prop in motion
Anyway - a real problem withsome props is that the imbalance is NOT along the prop length axis
This can be found using a very accurate balance ,which will sho that one blade always hangs at an angle
not vertically or random stopped position.
In these cases the out of balance point is vertically oriented -

for example if the blade always stops at -say 10:00 and 4:00 o clock-- the weight which is causing this ,is at 6:00 o clock- or in the hub
Try tiny dabs of clay and add at this point -till you get random stopped blade positions

It can be tricky but it's worth learning. Final weights can be another trick -especially if the real issue is a prop hub with a void in it or a hole off center or horizontal alignment. The finished product should have perfect blade tracking and random prop stopping on a frictionless balancer.
Ahhh penny drops!!! Thank you that explanation makes sense for me - but before I butcher a prop .... just to check my understanding - I am adding weight to 12 oclock (in your example) as 6 oclock is heavy - (at the hub) so much so that it outweighs the blades for true balance!??
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Old Jul 28, 2011, 12:10 PM
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Originally Posted by mutha View Post
Ahhh penny drops!!! Thank you that explanation makes sense for me - but before I butcher a prop .... just to check my understanding - I am adding weight to 12 oclock (in your example) as 6 oclock is heavy - (at the hub) so much so that it outweighs the blades for true balance!??
No- you first try to balance for end to end
then when it is obvious that the blades always stop at some angle- you correct balance by drawing an imaginary line , vertically thru exact center of prop mounting hole THAT is where imbalance is occurring
hub imbalance on wooden props is common -on a well engineered injection molded prop - with precision holes - it should be non existant - but on some it is not
Please note corrections!!
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Last edited by richard hanson; Jul 28, 2011 at 04:34 PM. Reason: incorrect statement
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Old Jul 28, 2011, 04:34 PM
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Canton, Michigan USA
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Originally Posted by richard hanson View Post
No- you first try to balance for end to end
then when it is obvious that the blades stop at some angle (not 180 or 90 degrees) you change balance at the vertical line thru prop axis
hub imbalance on wooden props is common -on a well engineered injection molded prop - with precision holes - it should be non existant - but on some it is not
APCs are sometimes a hassle because they are often off center with the dreaded 10-4 balance point I end up adding weight to the center hub to get it to park any where.
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Old Jul 28, 2011, 07:01 PM
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APCs are sometimes a hassle because they are often off center with the dreaded 10-4 balance point I end up adding weight to the center hub to get it to park any where.
I sometimes use baking soda and CA to make little lump on the hub
Oddly enough I have never seen the GWS props off balance . The straight blade 12x8 or 11x7 runs smoothly on motors like the 480 EFlite. They also are absent a "node" of vibe as you ramp up power slowly. Again most problems I found were on smaller sizes - 9" etc..
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Old Jul 28, 2011, 07:13 PM
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Canton, Michigan USA
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Originally Posted by richard hanson View Post
I sometimes use baking soda and CA to make little lump on the hub
Oddly enough I have never seen the GWS props off balance . The straight blade 12x8 or 11x7 runs smoothly on motors like the 480 EFlite. They also are absent a "node" of vibe as you ramp up power slowly. Again most problems I found were on smaller sizes - 9" etc..
Thick CA works well too.
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Old Jul 28, 2011, 07:24 PM
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Australia, VIC, Melbourne
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Originally Posted by richard hanson View Post
No- you first try to balance for end to end
then when it is obvious that the blades always stop at some angle- you correct balance by drawing an imaginary line , vertically thru exact center of prop mounting hole THAT is where imbalance is occurring
hub imbalance on wooden props is common -on a well engineered injection molded prop - with precision holes - it should be non existant - but on some it is not
Please note corrections!!
Yes, sorry Richard I was not fully explanatory - I did mean once you had established that no further (or any) amount of end to end balance is going to change the way it comes to rest - I have one APC prop that has been reamed to 8mm and will only sit in a "9:30 - 3:30" when one particular side is down. Being wet behind the ears in terms of this aspect of the hobby (dry and crusty in years ... ) I knew it had to be something like you have explained - i trust one gets better at it in time ... I probably could have cut and matched 50 ribs in the time it has taken to balance this prop!
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Old Jul 28, 2011, 07:58 PM
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Originally Posted by mutha View Post
Yes, sorry Richard I was not fully explanatory - I did mean once you had established that no further (or any) amount of end to end balance is going to change the way it comes to rest - I have one APC prop that has been reamed to 8mm and will only sit in a "9:30 - 3:30" when one particular side is down. Being wet behind the ears in terms of this aspect of the hobby (dry and crusty in years ... ) I knew it had to be something like you have explained - i trust one gets better at it in time ... I probably could have cut and matched 50 ribs in the time it has taken to balance this prop!
I think I have the twin to that prop--
trying to get exact on some drilling setups -just ain't possible
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