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07-29-2010 02:32 PM
Max
Re: Balancing Blades

Quote:
Originally Posted by Riddick View Post
Quote:
Originally Posted by nickzz1 View Post
My way , check both blade on a scale I use .01 scale , mark them , take the heavy blade find the C.G. mark it, put both blade together with a rod or bolt & mark the light blade, so you going to kill 2 bird with 1 stone, now put both blades on main heli shaft line them up 90 deg ( both C.G. marking ) roll them if the light blade fall first put tape on the light oppsite side( bolt-end ) , if the heavy blade fall first put the tape on the light blade ( tip ) THEY MUST FALL & weight THE SAME
I have found this method to be the best.
I respectfully disagree. There are 2 different methods for balancing blades, both work very well, the method you choose to follow will be based on personal preference. In the case of the OP, he is already using what I call a "dynamic" balancing method, which is a lot less tedious is as much as all you do is add weight to the low blade while it is on the balancer until the blades hang level and that is it, no CG marking or weighing is necessary. I explained it a lot more on a previous thread regarding balancing here:

Quote:
Originally Posted by Max View Post
I dont mean to take this thread off topic, but to answer the question of the two terms I used to describe blade balancing, there are 2 ways to balance a set of blades, one that is CG and mass dependent and one that is not.

When I learned the 2 methods, the term we used to describe the difference between the 2 is static balancing is a "one-off" balancing process and the dynamic balancing is when you put the 2 blades opposite each other on a balancer, hence the movement on the balancer being "dynamic".

Dynamic balancing DOES NOT require the mass or CG of the blades to be matched. Static balancing MUST have both blades identical in mass and CG.

Does this make sense so far?

Explanation of what I call "Dynamic" Balancing
To understand the difference between the two, one has to understand that you CAN use a single bladed propeller on an airplane engine. You only need to look at the C/L speed models to see that they use a single bladed propeller on their planes. (I made several of these types of props back in the '70's) What makes the single bladed propeller work is that the propeller is balanced by a counterweight. The heavier the counterweight, the closer it needs to be to the hub. The lighter the counterweight, the further it needs to be from the hub. In either case, the MASS and CG difference between the blade and the counterweight do not matter. To balance out a pair of blades in this fashion, you need a balancer. After you install a pair of blades, you find the high blade and add mass to the tip until the blades balance and you are done.


Explanation of what I call "Static" Balancing
As I mentioned earlier, Static balancing is a one-off process where you do not use a balancer device. All you need to do is match the blades in mass and CG. Without going into a lot of detail, the only tools you need is a straight edge(a razor works best) and a scale. The straight edge is used to find and mark the CG of each blade, and the scale is used to measure its mass. This is done one blade at a time. Once you have the Mass and CG of each blade ,you compare them to each other.
If the CG is off, you need to add mass to the light blade to move the CG in line with the heavier blade. Once the CG is correct, you re-weigh the mass of both blades and then ADD just the right amount of mass to the lighter of the 2 to get it to match the mass of the heavier blade. You add this mass right on the CG thus preserving the CG relationship between the 2 blades

Phew.... Sorry for the long-winded explanation but it was necessary to allow you to understand the differences between the 2 processes
07-28-2010 03:02 PM
nickzz1
Re: Balancing Blades

ya Man !!!!
07-28-2010 02:25 PM
belcom
Re: Balancing Blades

Yep, Nick is right. Same way I do it but using electric tape makes it much easier and faster to get both balance and COG done quickly.
07-28-2010 02:21 PM
Riddick
Re: Balancing Blades

Quote:
Originally Posted by nickzz1 View Post
My way , check both blade on a scale I use .01 scale , mark them , take the heavy blade find the C.G. mark it, put both blade together with a rod or bolt & mark the light blade, so you going to kill 2 bird with 1 stone, now put both blades on main heli shaft line them up 90 deg ( both C.G. marking ) roll them if the light blade fall first put tape on the light oppsite side( bolt-end ) , if the heavy blade fall first put the tape on the light blade ( tip ) THEY MUST FALL & weight THE SAME
I have found this method to be the best.
07-28-2010 01:40 PM
nickzz1
Re: Balancing Blades

My way , check both blade on a scale I use .01 scale , mark them , take the heavy blade find the C.G. mark it, put both blade together with a rod or bolt & mark the light blade, so you going to kill 2 bird with 1 stone, now put both blades on main heli shaft line them up 90 deg ( both C.G. marking ) roll them if the light blade fall first put tape on the light oppsite side( bolt-end ) , if the heavy blade fall first put the tape on the light blade ( tip ) THEY MUST FALL & weight THE SAME
07-25-2010 08:08 AM
belcom
Re: Balancing Blades

There's another benefit to using electrical tape for balancing. Once you've got your balance correct and it is spot on you can move the electrical tape further or closer on the blade to get the COG correct as well. Can't do that with clear scotch tape.
07-25-2010 05:16 AM
Max
Re: Balancing Blades

I use colored electrical tape. Comes in Red, Blue, green, etc.

It also doubles as tracking tape.

Quote:
Originally Posted by rotormonkey13 View Post
Nope, no particular kind. As long as it's a reasonable weight and sticks well you can use whatever you like.

One thing worth mentioning is when you put the tape on, make sure the ends face the trailing edge of the blade. Otherwise the tape will start to lift in flight, cause drag and make funky noises
I Lay it down same way as RotorMonkey, so the airflow doesn't lift it.
07-24-2010 08:30 PM
Jiver
Re: Balancing Blades

Clear scotch tape. You want to add weight to the lighter blade.
07-24-2010 05:37 PM
rotormonkey13
Re: Balancing Blades

Nope, no particular kind. As long as it's a reasonable weight and sticks well you can use whatever you like.

One thing worth mentioning is when you put the tape on, make sure the ends face the trailing edge of the blade. Otherwise the tape will start to lift in flight, cause drag and make funky noises
07-24-2010 03:56 PM
mcx
Re: Balancing Blades

i use scotch tape, the clear stuff when balancing blades.
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