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HelicopterMain Discussion › balancing a main blade question
02-23-2014 06:46 PM  3 years agoPost 1
wc_wickedclown (RIP)

rrProfessor

long beach calif

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do you start at the middle or the end where should i put the weight ?

Insha Allah made in america

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02-23-2014 06:58 PM  3 years agoPost 2
jtv62161

rrApprentice

Oakdale Pa / Quaker city Ohio / Bradenton FL

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balancing

I believe you find the cg of the blade and place it there there are a lot of blade tracking videos on utube showing this

Logo 400/400se/550se/Align 550/700DFC

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02-23-2014 07:06 PM  3 years agoPost 3
dkshema

rrMaster

Cedar Rapids, IA

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Find the center of gravity of each blade. Add weight to the light blade at its CG. Ideally you want each blade to weigh the same and have the same CG location. If the CG of each blade differs by an appreciable amount, correcting CG and balance becomes quite a task.

What blades are you balancing?

Blade manufacturing has come a long way and the majority of carbon fiber blades are well matched and having to balance is no longer necessary.

-----

Finding the CG doesn't take any special tool...

I used a single-edge razor blade in a Pana Vise:

This next picture just shows a piece of tape I placed on the blade to illustrate the process a bit more clearly at the end of the process. I don't normally put this on the blade when balancing.

Place the blade on the sharp edge of the razor blade (bottom surface down) at a 45 degree angle. Move it back and forth till it balances. Then very carefully slide the blade along the razor, making a slight mark on the bottom side.

Turn the blade 90 degrees, balance again, and then slide the blade again on the sharp edge of the razor to make a second mark on the bottom side.

Flip the blade over. Where the two marks intersect is the CG of the blade.

-----
Dave

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

Team Heliproz

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02-23-2014 08:39 PM  3 years agoPost 4
FRANK R

rrApprentice

Scarborough, ontario, canada

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+ 1...The two post above is the best and the only way everyone should do Blade balancing!

Demon in ME... Kosmik = Kostme

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02-23-2014 09:19 PM  3 years agoPost 5
Flyin for Jesus

rrVeteran

Dana Point, Ca. 92629

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2 ways to balance...

CG and blade weight... weigh both blades and see which one is heavier. set the lighter blade on the scale and add a piece of tape ( or whatever you're going to use to add weight and keep cutting the tape smaller until the lighter blade with the tape weighs the same as the heavier blade. ( don't stick the tape yet.

Find the CG of the heavy blade... and then mark the same spot on the lighter blade and move the piece of tape around until you get the CG to be the same. Now stick the tape there and you have matching weight and matching CG blades.

Only drawback to this is sometimes the tape piece isn't heavy enough to move the CG to match the other. Then ( lets say you had the tape piece out at the end of the light blade ) now... add a piece of tape close to the blade grip end of the heavier blade... then repeat all the above steps.

2nd. way is to use a see saw type balancer. Just add tape to the blade that is higher at the tip until they both match and are level.

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02-23-2014 10:21 PM  3 years agoPost 6
GREYEAGLE

rrElite Veteran

Flat Land's

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Also note that I've noticed if small 450 blades set's for a long time in their holder's they are pretty dynamic far as the last tracking. Before I start chasing adjustments - I normally fly a few packs and the applied load brings them right back onto spec.

Never met a set that was absolutely perfect

Must be do to size and construction

greyeagle

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02-24-2014 07:14 AM  3 years agoPost 7
wc_wickedclown (RIP)

rrProfessor

long beach calif

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thank you

Insha Allah made in america

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02-25-2014 03:20 AM  3 years agoPost 8
AirWolfRC

rrProfessor

42½ N, 83½ W

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I don't know why people make it so difficult.

With only two blades, just bolt them together with a blade bolt and balance the assembly on the bolt.

Put weight on the light blade tip till balanced.

You're done.

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02-25-2014 03:32 AM  3 years agoPost 9
Rob43

rrKey Veteran

Midland, MI USA

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Rob

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02-25-2014 03:43 AM  3 years agoPost 10
Flyin for Jesus

rrVeteran

Dana Point, Ca. 92629

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I don't know why people make it so difficult.
With only two blades, just bolt them together with a blade bolt and balance the assembly on the bolt.
Put weight on the light blade tip till balanced.
If you balance them this way... you better make sure the blades are 180 degrees from each other. 179.95 is not good enough.

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02-25-2014 03:17 PM  3 years agoPost 11
AirWolfRC

rrProfessor

42½ N, 83½ W

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Even 120º can work. You balance by the blade bolt with the blade bolt horizontal.

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02-25-2014 09:45 PM  3 years agoPost 12
Flyin for Jesus

rrVeteran

Dana Point, Ca. 92629

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Sure, like an airplane prop. However, it's not balanced if it doesn't stay still in all orientations...
See saw balancers are probably the cheapest and easiest.

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02-25-2014 11:39 PM  3 years agoPost 13
AirWolfRC

rrProfessor

42½ N, 83½ W

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Why are you trying so hard to complicate the matter ? ?

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02-26-2014 12:38 AM  3 years agoPost 14
Flyin for Jesus

rrVeteran

Dana Point, Ca. 92629

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I'm a machinist... I'm accurate. ( on what matters )
A friend of mine wants to get his heli all to read perfect with his Soko heli setup tool. I told him he cannot and it's not necessary because there is slop in servos, in the swash... .1 degrees is pointless.

Blade balance... The better balance... The less vibration.
Slightly out of balance... Slight vibes
Significantly out of balance... Significant vibes.

This is a case where it does help to be as accurate as possible. Not meaning to be difficult.

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02-26-2014 12:42 AM  3 years agoPost 15
Rob43

rrKey Veteran

Midland, MI USA

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AirWolfRC: You're not serious?! Static balance without CG correction? Not dynamically balanced. Better doublecheck that one before you go much further. It's not complicated.

Rob

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02-26-2014 12:44 AM  3 years agoPost 16
ScaleNewbie

rrNovice

Ryde Isle Of Wight UK

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Put weight on the light blade tip till balanced.

You only do this if the C of G is not matched on both blades,if you add weight on tip on blades that have identical C of G you will throw out the C of G, and at certain RPM the blades will flutter or come out of track and cause vibes.You add weight on lighter blade at C of G point to balance them as DK said.

The proper way to balance blades is as DK said.

I have only ever added tip weight when I needed to make the C of G identical to the other blade, and even then it is not always on the tip, sometimes you add it nearer the root. Depending on where on the blade the C of G is out.

It gets more complicated when the chord C of G is out, then you have to really start playing around, But in the olden days that is what we used to do when we made our own blades.

Ryan

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02-26-2014 01:12 AM  3 years agoPost 17
wc_wickedclown (RIP)

rrProfessor

long beach calif

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putting weight on the tip.

guess that would depend if they were fb blades or fbl

fbl blades are weighted at the tip and fb blades are weighted at the root ?

Insha Allah made in america

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02-26-2014 01:21 AM  3 years agoPost 18
Flyin for Jesus

rrVeteran

Dana Point, Ca. 92629

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Wow, this has gotten out of hand...

Okay... You can balance blades on a see saw type balancer without ever knowing the CG and get it right on...
You can do it with the bolt through the blades as mentioned above... It's just not as accurate. With the right tools, you can bolt the blades together within .01 degrees and be accurate. You just cannot do this by eye.

When weighting the blades to balance... Inside or outside of the blade doesn't change the CG enough to affect your FB or FBL blades.

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02-26-2014 01:24 AM  3 years agoPost 19
ICUR1-2

rrElite Veteran

Ottawa, Ontario

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guess that would depend if they were fb blades or fbl
fbl blades are weighted at the tip and fb blades are weighted at the root ?
the cg is moved further out on the FBL blades compared to FB blades

DK has it right

spending time, paying attention

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02-26-2014 02:22 AM  3 years agoPost 20
rcflyerheli

rrKey Veteran

Granbury, TX USA

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I am not disagreeing with DK's method at all, with one exception -- the part about scribing marks in the surface of the blade with a razor blade. I would seriously question that that puts damage on the surface of the blade that is highly stressed and could possibly lead to blade failure.

Maybe I am over analyzing the loads on the blade, but the CG and the CL are the two points where the loads are concentrated. I sure wouldn't want to add a stress riser in that particular location.

FWIW, I use the same procedure on a piece of music wire, but I mark the location with a felt tip marker. I don't think any of my blades have contributed to vibration errors using the felt tip procedure.

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

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