RunRyder - A blade balance that works

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Beginners Corner > A blade balance that works

Way2slow
Veteran
Location: Jeffersonville Ga

I've constantly had more vibration that I felt I should on my 600N and have tried a number of different balancing methods, just weighing, just balancing on a balancer, finding center and balancing until centers are the same, etc. but they all seem to vibrate. This is especially true with cheap wood blades. This has always been such a problem on my Trex that I've never been able to use anything but top quality CF blades so I wouldn't use it when practicing anything new. $100 blades are hard to eat after you break a set of them.

I also build high performance engines and decided to adapt my my rod balancer (big end, little end, total weight balancing to +/- 2 grains) and try that. I balanced at set of $25 dollar wood blades that shook everything I put them on balanced the standard ways and tried them on my Trex. They spun smoother than any high dollar CF blades I've run.

If you have a set of good scales that will weigh within a couple of grains or 0.1 grams you might want to fabricate a way to support the blades level and try using the big end, small end and total weight method. They are sooo smooth, it's worth it. Just remember, they have to be supported exactly the same each time, a few thousands of inch difference will make the readings all wrong.

07-06-2008 01:10 AM

bigdog714
Senior Heliman
Location: Chardon, Ohio U.S.A.

You need a small vice and a razor blade, balancers are a waste of money, put the razor in the vice (sharp side up, LOL), find the CG of each blade and mark it. Run the blade bolt through both blades to line them up, if theres more than 2mm differance between the two CG marks you will have to add weight to the tip of the blade the has the CG mark farthest from the root. Rapp the tape around the blade before the leading edge curves to the tip. I use electrical tagging tape from the local hardware store, its thin and comes in five colors. The reason for this is so the arch of the blades match during flight.

Now that is done, you have to balance the blades to each other, I use a digital jewlers scale, a 600g is about $20 on e-bay. Weigh each blade, 0.2g is fine, anything more requires balancing. Now you add tape to the CG of the blade to balance.

Next is tracking, put a colorful piece of tape along the leading edge of one blade near the tip. Hover the heli and look to the right at the tips of the blades, it should be one nice straight line, if its a wide band the tracking is off. Look closely at the tips, you want to indentify the high blade, if you see the tape on the high blade, thats the one to adjust, if not its the other. The short ball link that attaches to the blade grip needs to be adjusted to turn the leading edge of the blade down, start with one turn, it might take two or three.Get it the best you can its hard with woodies, remove the tracking tape and your done.

Make sure that you flybar is centered, your paddles weigh the same and are mounted the same distance from the ceter shaft.

Align T-Rex 600EP
Align T-Rex 600N
EVO 90

07-08-2008 02:28 AM

SSN Pru
Elite Veteran
Location: Massachusetts

Quote

That's fine and dandy but overkill. the CG's dont have to be exact so long as the moment is the same between the two blades. To be sure this happens, just bolt the two blades together, align them straight and balance them see-saw style.

Your method works too but is overkill.

07-08-2008 05:25 PM

f penfold
Senior Heliman
Location: uk

make sure that the ends of your woodies are sealed if not your smoke can leach in to them and the start to delaminate also make sure you epoxy the root if the are going to brake they normally brake there. carbon blades are much stiffer than woodies and so they reacte diffrently to your in puts I dont know what type of flying you do but for 3d you really should be useing carbon ive boom struck a raptor with carbons before but with woodies it would of happened alot sooner

07-08-2008 05:27 PM

bigdog714
Senior Heliman
Location: Chardon, Ohio U.S.A.

Actually with woodies balancing one axis isn't enough, it is supposed to be four, and theres no tape, you sand and contour the blades. This process was given to me by a man that made his own wood blades. Granted it won't do much on a 325mm blade, but it will on 500-700mm. Besides if the blade arch doesn't match, how do you set the tracking? I have a couple sets of nice symetrical wood blades I like to fly once in a while, I love the sound they make, you realy turn some heads when flying them, and they track perfectly.

Everyone should use a system they are compfortable with, I am meticulas when it comes to my helis, and I like to use some of the older proven methods, I like tradition.

Now when it comes to Carbon Fiber blades I don't even check them unless I have a head vibe. If you look under a good set of carbons you can see balancing plugs. Takes the guess work out of it.

Align T-Rex 600EP
Align T-Rex 600N
EVO 90

07-08-2008 08:13 PM

SSN Pru
Elite Veteran
Location: Massachusetts

simply balancing the moment created by the two blades is more than sufficient. Matching CG's has no additional effect. Try it and find out for your self.

Others were convinced here:

http://www.runryder.com/helicopter/t352560p1/

http://www.runryder.com/helicopter/t437692p1/

In the end, though, do it how you like

07-08-2008 08:24 PM

bigdog714
Senior Heliman
Location: Chardon, Ohio U.S.A.

I also read an article in one of the heli magazines sometime ago, that showed the differant axis and how the blades arch and the physics behind it, it was quite interesting.

The deeper I get into helis it amazes me all the fine tuning thats required for the bird to perform at its max no matter the flight position, balance, tracking, symetry, phaseing, runout, power to wieght ratio, I love it.

Align T-Rex 600EP
Align T-Rex 600N
EVO 90

07-08-2008 09:52 PM

Way2slow
Veteran
Location: Jeffersonville Ga

Just thought I would mention a method I found that I like. Like I said, I've used all the methods mentioned over the past six months and none of them spun as smooth as the method I used when balancing rods for my race engines. I haven't tried any CF blades because like someone else mentioned, I usually find they spin fairly true out of the box. My 600N is the only one that seems to be so touchy about the balance anyway. I can run blades on the K-50 or the Raptor that cause them to have a slight vibration but very flyable, but put them on the Trex and the whole thing is shaking, badly.

I also have never had a problem with CF blades, it's just the woodies. I prefer running woodies when doing something new that's probably going the increase the odds of me crashing, they give me an up front $75 discount on the repair bill

07-08-2008 11:24 PM

bigdog714
Senior Heliman
Location: Chardon, Ohio U.S.A.

I had a head vibe on my 600N, it was fine at normal 1750, and Idle1 1900, but in Idle2 2050 you could see the skids shake. Turns out I had thrown a bolt from the fan mount. The fan actually came unbolted before I discovered it, other than the tinny rattle from the aluminum fan, it flew fine, even the Gov. was smooth. Just lucky I guess.

Align T-Rex 600EP
Align T-Rex 600N
EVO 90

07-10-2008 01:48 AM

daytona7
Heliman
Location: Ocala, FL USA

Balancing with tape

Has anyone tried balancing their blades with Golfing Lead Tape instead of 2-6 wraps of tracking tape? Have something like 50 foot by 1/2 inch wide roll of it laying around someplace. If used, where would be the best place to put it? On the top, bottom or forward edge, middle or near the end of the blade? Someone told me a while back that golf pro shops can not sell whole rolls anymore but you can get small measured weight strips at most sports stores. Might try it on one of my off balance wooden blade sets.

07-20-2008 02:08 AM

Pull-n-Pitch
Veteran
Location: Mt. Dora, Florida (USA)

If your wrapping LEAD tape around a blade, then something is really wrong............
It could be the C/G or just cheap wood blades...I know you would not have to do this with a "medium priced" set of Carbon Fibers....
You gotta draw a line somewhere...
USE a Hi-Point balancer and gram scale and find the problem!

Pull-n-Pitch

07-20-2008 03:02 AM

daytona7
Heliman
Location: Ocala, FL USA

Lead tape

Should not have to put anything larger than the size of a dime on a wing and that should still be lighter than 2-4 wraps of tracking tape. Nice thing about the tape is that it can be cut any size needed and it does not have to be stuck on the wing to find the spot and size needed while balancing. Try that with tracking tape. If you or any of your friends golf, see if will give you a 1 1/2 inch strip and the next time you balance a wing, lay a small cutoff peice on it. If no one has any, e-mail me your address and I'll send you some to try. That is as soon as I find my roll.
I'm using e-Flite wood blades for practice and half the blades are warped right out of the package.

07-20-2008 12:12 PM

stickyfox
Key Veteran
Location: Troy, NY, US

Quote
simply balancing the moment created by the two blades is more than sufficient.

Quote
Actually with woodies balancing one axis isn't enough

Both statements are actually true; they're just overlooking the fact that blades can be off-balance in their width axis as well as their length axis.

Blades have to be balanced both on- and off- axis to eliminate vibration. If you match both the CG and the mass of the blades, the blades will be matched on both axes. In theory, if the blades are totally different but balanced for identical moments on the head, this will also be true. However, it is possible to match moments on a pair of blades and have them out of balance off-axis. This is because the friction in a balancer axis can be enough to mask the off-axis unbalance. It's also very very difficult to align the blades in the grips precisely enough to make this measurement. That's why some people prefer to sand and tape them until the CG's are in exactly the same place.

Personally, I like to paint a few colored dots on the rim of the head button and just look for vibration. If head is perfectly balanced, the dots will look like a single ring. If there is any unbalance, the dots on the heavy side will be outside the ring, and the dots on the light side will be inside. It takes a few minutes. Would I try this standing over a 700mm heli with new blades? In that case, I'd probably rough it up first using one of the above methods.

-fox

07-20-2008 02:50 PM

HOMEPAGE

Ace Dude
Elite Veteran
Location: USA

Koll Rotor Pro for me.

07-20-2008 04:29 PM

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Beginners Corner > A blade balance that works

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