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HelicopterBeginners Corner › Blade Balancing Question
09-15-2017 02:06 AM  5 days agoPost 1
Big Dave 365

rrNovice

IL

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I am trying to balance a set of blades for a 450 size heli.

I found the CG of each blade and moved it to the same location by adding tape at the root.

I then locked both blades on a shaft and checked for balance by adding tape at the cg of the light blade.

After doing so, if I weigh the blades, they are always .1-.3 grams out.

Is this correct?

Thanks,

-Dave

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09-15-2017 02:21 PM  4 days agoPost 2
Flyin for Jesus

rrApprentice

Dana Point, Ca. 92629

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Your method sounds good except I don't understand the part where you lock both blades on a shaft.
What do you mean by that?

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09-15-2017 02:36 PM  4 days agoPost 3
BeltFedBrowning

rrKey Veteran

Kansas City

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If you add the tape to the outside of the blade to move the CG, it will add more to the balance of the blades than tape at the root.

perfer et obdura; dolor hic tibi proderit olim

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09-15-2017 03:36 PM  4 days agoPost 4
ICUR1-2

rrElite Veteran

Ottawa, Ontario

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After doing so, if I weigh the blades, they are always .1-.3 grams out.
Is this correct?
Yes

If the blades are exact same before starting then there will be a difference after because of added tape

spending time, paying attention

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09-15-2017 03:42 PM  4 days agoPost 5
ICUR1-2

rrElite Veteran

Ottawa, Ontario

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The problem is , is the method you are using.
On a smaller model you won't get to appreciate the effort . However on large blades it would be more appreciated.

As long as the blades weight are equal ,.Have at it .

spending time, paying attention

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09-15-2017 03:49 PM  4 days agoPost 6
BeltFedBrowning

rrKey Veteran

Kansas City

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You will add tape to the outside of one blade to move the CG outward. Then add tape to the CG of the lighter blade to balance them.

perfer et obdura; dolor hic tibi proderit olim

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09-15-2017 03:56 PM  4 days agoPost 7
Flyin for Jesus

rrApprentice

Dana Point, Ca. 92629

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You will add tape to the outside of one blade to move the CG outward. Then add tape to the CG of the lighter blade to balance them.
Instead of moving the CG outwards on one blade, he is moving the CG inwards to get them to match. This is my preferred method as well because tape at the root sees lower airspeed... it changes the blade profile at a spot that it really doesn't matter and the tape tends to stay on better there.

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09-15-2017 04:03 PM  4 days agoPost 8
CoachE

rrApprentice

Cincinnati, ohio -usa

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Hmmm. I have always just found the cg of the heaviest blade. And then just adjusted the lighter blade up to match. I guess i must be mis reading something.

Team JR / Get !T - Got !T - Perfect !T

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09-15-2017 04:26 PM  4 days agoPost 9
Flyin for Jesus

rrApprentice

Dana Point, Ca. 92629

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Hmmm. I have always just found the cg of the heaviest blade. And then just adjusted the lighter blade up to match. I guess i must be mis reading something.
It depends on the starting weight of the blades. If the heavier blade has a CG closer to the root, then you can easily adjust the lighter blade CG closer to the root while adding weight to get the same total weight. But you can easily do it the above mentioned way no matter each blades's weight, you might have to use more tape though.

My blade balancing techniques have changed over the years.

1.) add tape to root ( or end ) of blade to match CG, then add weight at the CG mark of the lighter blade to get equal blade weights.

2.) Use a Koll rotor pro and set each blade that way where you can add a single piece of tape and nail both the CG and total weights in one shot.

3.) My current method... Balance the entire head as a whole. I use a DuBro TRU-SPIN PROP BALANCER and a spare mainshaft to do the job. I can use a single piece of tape to get it balanced and it also compensates for any differences in blade grips, head block or anything really. Only drawback to this method it you can't just swap blades from one heli to another. You have to re-balance each time. But I don't switch blades from one heli to another, each one has its own blades.

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09-15-2017 09:50 PM  4 days agoPost 10
MattJen

rrElite Veteran

UK

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find the c of g, match the c of g, balance on the c of g.

All The Best

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09-16-2017 11:18 PM  3 days agoPost 11
dkshema

rrMaster

Cedar Rapids, IA

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All this over 0.1 to 0.3 grams?

Fly them and sooner or later, the bug splatter will even the weight all out.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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09-17-2017 04:24 AM  3 days agoPost 12
rcflyerheli

rrKey Veteran

Granbury, TX USA

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Current blade manufacturers are generally pretty good about getting their CGs matched as a set, but sometimes the weights are slightly off, thus add tape to the lighter blade at the CG.

If I have found the CGs of the blades to be different, I have always subscribed to the theory of adding all the tape to the lightest blade. So what I do is adjust the CG of the lightest blade to match that of the heaviest one, then if more tape needs to be added to balance the weights, then I add it to the lightest blade to balance.

I agree .1 to .3g is insignificant.

Goblin 700, Trex 700DFC, Gaui X7, Logo 690SX, Logo 600SX; Trex 470 Trex 500
Amain Team Rep

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