darkfa8

My Feedback: (19)

I'm looking into scales, digital and analog... and I'm wonder how accurate do they have to be to adaquately balance blades? 1/10, 1/100 of a gram, etc..?

rusirius

Actually I myself got a little blade balancer from heliproz. (http://www4.mailordercentral.com/hel...?number=102280) for about $45. It works fantastic. Scales alone will let you statically balance the blades, but won't help with dynamic balance. This balancer will do both... You lay the blade on top and slide it up or down till it balances perfectly... That lets you find it's CG... Do that for both blades and make sure they match.. If not, add tracking tape to the blade with the CH closest to the bolt hole... Once the CG's match, you can pop the blades on the balance together (balancing their weight against each other) and add tracking tape to the CG of the lighter blade till the match... Viola.. perfectly statically and dynamically balanced blades.. In a pinch, you can use a razor blade glued to a piece of word or something to find the CG, but it's much easier with something like the above balancer.

pwterry

Try here for blade balancing (under "basic setup" ):
[link]http://www.dream-models.com/eco/flying-index.html[/link]

Most everything used here can be done with things around the house. A long snug fitting machine screw, two nuts, and two water glasses of the same height can be used to balance the blades to each other. Electrical tape for weight. Colored electrical tape for "tip markers".

Charlie

Works great.

1ight

Be careful with electical tape. I had the tape come off the blade when flying. Heard a big 'bang' and everything started to shake. Nothing happened, just rebalanced it again but get the tape thats gonna stay on there for good.

pwterry

No matter what you use to balance blades (electrical tape, airplane covering material, other tapes, etc.), always wrap the tape around the leading edge of the blade. If you don't, air will get under whatever you use and rip it off. A little CA (superglue) along the edge will help, but the glue will become a permanent part of the blade (remove the tape and be left with a ridge of CA on the blade).

tanasit

Two tips from years of flying (and crashing):

1. Try the heat shrink in stead of the tape and it will never come off in flight. But if you only have the tape, wrap it in such a way that the very end doesn't face the leading edge. Not only the speeding air stream will peel it but also the lubricant from the rotor head ball bearings with the help of the centrifugal force will find the way to go under the tape opening and loosen it eventually.
2. Many times I balanced the blades perfectly only to find out that it still doesn't fly smoothly but with some head vibration. Until I visited a German rc helicopter office and noticed their technician balancing the "whole rotor head" with the main rotor shaft on it's side laying on the balancer with a big weight attached to the bottom part of the shaft. They even arrange the setup so that the effect of the earth magnatic field is minimum!

How accurate do you want for the scale? At first I didn't think much and got a 1/10 gram one. One day I was flying with nice and smooth rotor head and a few minute later I could see the vibration, so I landed and notice the fresh traces of sticky "insect residual" on the bottom of one blade!
Now I use 1/1000 gram analog with dial type scale. It will weigh a strand of hair.

AV8

well I can buy it up to the point of the "Earth's Magnetic Field" portion. Unless you, or in your example, "They" are putting millions into a lab that will account for the electro static generation of the blade that will affect the "Earth's Magnetic Field" around the helicopter when it is at speed. And not a moment before. So unless they are balancing that "Entire rotor head" at 1650-ish rpms.... well then.... I think they are selling you something or at least trying to get you to believe something that is untrue. Now as for whether or not htey actually told you that... or that they actually thought thats what they were doing... thats a different issue.

Also note that the solor flares (Storms) on the sun change the magnetic flux here on the Earth to the point that it slows the speed of radio frequencies.... might want to tell "Them" to keep that in mind.


I am in full support of your flying it until its shaking and unstable. There is a such thing as "Good enough" that will still keep the helicopter well within a safe operating range.

Then again, if you want to spend more time making it "perfect" which it will never be, thats fine too. I mean considering that I know about the solor flares from working on building an "Accurate" clock.


To each their own.
Keep it in the air,
-Steven

-pkh-

My Feedback: (2)

I'd forget the scale and just get a simple balancer from Heliproz, or you can just buy some CF blades that come pre-balanced. I still like to check the CF blades with a balancer, just to be sure... but you shouldn't have to mess with them, just bolt them on...