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Midland Helicopters . HeliProz . ZoomsHobbies

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Main Discussion > Balancing Main Blades
 
 
Brian Weekley
Senior Heliman
Location: Victoria, BC Canada

Is anybody following the main blade balancing procedure outlined in Ray Hostettler's newest edition (page120)? If so what is your experience attaching chunks of lead to the blades with CA. I decided to use his procedure on a new set of 710 SAB 3D blades. Starting at 190 grams I CA's six chunks of lead to balance the blades chordwise on my Koll Pro. I added 2 grams of lead chunks to that blade as he described and then added another 1.5 grams of lead to the light blade to match the spanwise C of G. I haven't completed the third step namely adding lead or tape to match the weight of the blades but will do that tomorrow. When all is said and done I have three puddles of CA within a couple of inches of the blade bolts that contain chunks of lead and look awfully like 00 buckshot.

Some words of assurance from somebody who used this method and survived the test flight would be greatfully appreciated.
03-17-2002 Over year old.
 
 
pwood
Key Veteran
Location: Dubai - UAE

Yea, the lead looks like a mess

It is the only way i can see how to do it. I first used "press stick" as trial run. CA is so final !! (Its a stuff like chewing gum to stick posters to walls)

I also stuck a little to the TE of one and a little to the LE of the other. So all the lead was doing work. The press stick (chewing gum) works as you can balance it with only two pieces, one on the LE and one on the TE of each blade. This gets the chord wise balance ok, then when you check span wise and it is out just move the amounts arround, some off the LE and onto the TE to sort out the span wise balance while keeping the chordwise balance OK.

Only a small bit on the cg of one will be needed at the end.

Just play with it using press stick and when you have it spot on set it up again and take off the press stick and glue on lead to match. It take double the time but keeps the lead/ CA puddles down.
03-17-2002 Over year old.
 
 
Blair
Key Veteran
Location: Republic of Canuckistan

Chordwise balance

Hey Brian,

Give me the heads up when you are flying these blades so I can wear my vest and a goalie mask!

ducking for cover,

Blair
03-17-2002 Over year old.
 
 
CSCHWER
Heliman
Location: West Virginia USA

Did you fly these blades before you started the surgery? What ever happened to your bubble balancer and tracking tape?
03-17-2002 Over year old.
 
 
ALuminum2
Senior Heliman
Location:

When you crash you are going to have chuncks of lead flying at you.

SAB BLADES ARE FINE. DO NOT TOUCH THEM.

they might be a little unbalenced, but nothing major. If you get them in the same set then you can only wreck them by touching them.

Just bolt them on.
03-17-2002 Over year old.
 
 
MooneyDriver
Veteran
Location: Kent, Ohio

lead...

I just "borrowed" a shotgun shell from a friend, and extracted the buckshot. Next I just flatten them with a hammer. Thin CA holds them on the blade nicely. You might want to dab them with paint to match the blades. High quality blades usually don't need much work. I've had to balance cheap fiberglass ($25) blades, thought.

-Neil

Hey man, why does my lipo get bigger every time I charge it?
03-17-2002 Over year old.
 
 
Maxx
Key Veteran
Location: Shreveport Louisana

Brian; I don't know how much you paid for your SAB's but if I have to balance 'Glass or Carbon Fiber blades I return them to the place I got them from...I've NEVER had to put a piece of tape on a set of NHP blades and through the years I've had the 550's, 620's, 680 (S and C) and 710 (Razors and Sports)!. I own a Koll Roto-Pro and check every blade I fly...I've gotten some blades for $50.00 that I had to balance but I knew going in they were "marginal", but SAB's should be Damn near perfect...In any case I would NEVER glue something to the outside of the blade that is not in some sort of a "pocket" to contain the rotational energy within the blade itself...Ray certainly knows a lot about R/C helis; but on this point I do believe his way is not the best solution you can find... IMPO... Chris
03-18-2002 Over year old.
 
 
Stet
Elite Veteran
Location: Long Beach CA

Like Maxx said, the SAB blades should have been balanced from the factory. Perhaps you are trying to match singles from two different pairs? In Ray's old book he tells of a number of ways to balance. I use the tip balance method, weigh the tips, make them the same, then weight the overall and make them the same. I use this method on woodies, but rarely have to adjust the weight more than .25 gram, again unless you are matching blades from different sets. For the tip, you'd have to drill a hole and insert lead, and for the overall I just add washers under the grip bolt. Installing lead is a scary proposition as the inertia at the tip is severe. The only thing you should use to adjust the tip weight is tape.

You should never have to even think about adjusting the balance on a factory pair of composite blades. If they are off, return them.
03-18-2002 Over year old.
 
 
mark fadely
Senior Heliman
Location: indianapolis, indiana

just one point about balancing blades - spanwise balance has nothing to do with a shake in a machine - seems like it would since a spanwise difference on a playground teeter totter will cause one end to fall. But if the weight is the same on both sides of the center (or head) then the blades will run smooth no matter where the spanwise balance is assuming the chordwise balance is on as well. Proof of this is seen in single bladed propellers. One side has the blade, and the other has a counterweight with no blade at all. One other way to prove this is to put a set of flybar weights on and run up the machine to make sure it's smooth, then stop the blades and move one weight all the way out on the flybar shaft and the other all the way in. You will notice the machine will still run just as smooth as before. Sure there is going to be some dampening differences from one flybar paddle to the other especially because the flybar weights are so heavy, but with the small amount of weight that's needed to correct main blade spanwise balance it's no issue at all, so it's totally unnecesary to concern yourself with spanwise balance.

Mark Fadely
03-18-2002 Over year old.
 
 
Stet
Elite Veteran
Location: Long Beach CA

Dynamics of rotating systems

Centrifugal force is to the square of the distance from the axis. This is dynamic balance.

Whether the imbalance visibly shakes the machine might be a different story, depending on the overall spring mass damper system and frequency, i.e. resonance.

An unbalanced load is just that, and in a rotating system, not what you want from a reliability standpoint. An unbalanced load will excite the system at the rotational frequency.

If unbalanced, the mainshaft and its bearings will be taking a much higher load, and vibration levels will be correspondingly higher in the airframe, causing a variety of ills.
03-18-2002 Over year old.
 
 
Brian Weekley
Senior Heliman
Location: Victoria, BC Canada

Unbalanced Blades

None of the composite blades (V Blades, NHP, T&G's, Hi Products, SAB, MAH and no name) that I have balanced on my Koll Pro have been PERFECT. It has been pretty easy to get spanwise balance and CG perfect with bits of tape here and there. Cordwise CG is another matter. All of the blades have been different. The other point is that I have been slightly uncomfortable with putting tape on the outside half of the blade. To this point I have just satisfied myself with spanwise balance and Cof G and just ignored chordwise balance. I now want to build a set of blades that are PERFECT and see what the difference is.

That is what led me to pg 120 of Hostettler's new book. His technique seems to answer all issues but involves using CA to attach lead "wafers" to my pretty set of SAB 710's. I should finish the procedure today and will give them a test this week weather and income tax willing. Thanks to everybody for their input, especially Blair who has volunteered to spool up the blades for the first time.
03-18-2002 Over year old.
 
 
Maxx
Key Veteran
Location: Shreveport Louisana

Hey Brian, If you've never had a prefect set of NHP's straight out of the wrap you might need to send your Rotor Pro back to Ruleville MS. for calibraition...it might not be set for the magnetic anomilies found in Canada 'cause you're so close to the Pole...also, there is the lack of rotational velocity of the ground due to you being so high up the Globe...and last but not least; because it's so Damn cold there for so long and I know I wouldn't want to turn MY heater off even for a minute, are you sure the Central heat vent ain't blowing down on the place where you balance your blades??? Forced Air imperfections are mighty hard to balance out...either with buckshot OR tape!!! Chris (formerly of Vancouver B.C.)
03-18-2002 Over year old.
 
 
Brian Weekley
Senior Heliman
Location: Victoria, BC Canada

Rotational Velocities

Hi Chris .... it's great to hear from you. I was flying one of your canopies last week on the gasser I bought from Ron. I never cease to admire your excellent work.

On the subject of central heat and magnetic anomolies affecting my Koll Pro ... of course you are right!!!! Why didn't I think of that. Now I have to get my cold chisel out and hack off all that lead and CA on my SAB's.

With this rotational velocity thing how does it work way down south where you are close to the equator? Do you have to re-trim when you change directions? Also flying in that constant wind must be really tough!!!! This rotational velocity thing must explain why we don't hear from many heli fliers in the Congo.
03-18-2002 Over year old.
 
 
zoid555
Senior Heliman
Location: MN

How close are they supposed to be? I dont think many blades are exactly the same weight. How far can they be off before you need to balance them? I just got some 600mm SAB's and one is 140g the other is 140.6g. The cg is good so I am not going to mess with them but I would like to know how far off is too far off.
Thanks, Brandon
03-18-2002 Over year old.
 
 
ALuminum2
Senior Heliman
Location:

I just put a set of sab 680's carbons on my fury. I had all the linksk the same size as the other, I had sets of links. I put them on and my tracking was perfect.

LIke I say SAB BLADES ARE FINE. You pay all that money for them for a reason, they are built perfectly or close to it. There might be some exceptions. THe wooden blades are made cheap and they don't focus on balenceing as much. Why because they are 1/3 rd the cost.
03-18-2002 Over year old.
 
 
Ron Cosby
Senior Heliman
Location: Shreveport, Louisiana

Brian, with all the big $$$ you're aving on fuel (with gasoline) treat yourself to some VBlades, you don't need to worry about balancing those!!
Hope all is well with you, don't crash my old "baby",
Take Care!
03-19-2002 Over year old.
 
 
Brian Weekley
Senior Heliman
Location: Victoria, BC Canada

Ron's Gasser

Not to worry Ron ... your're baby is in fine shape and has been enjoyably flown this winter. The nice part about the gasser is that I can play around "close in" without smoking out the pits. I finally feel confident setting the needles. In "upgrading" my computer I lost your email. Send me a note ( maac16324@shaw.ca ) off the board and give me your email. Got to keep in touch with one of the "good guys".
03-19-2002 Over year old.
 
 
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