Should you need to balance your paddles?

[Jermo]

I've recently had some time to reflect on my Heli and had forgotten to ask this important question. Should I need to balance the flybar paddles? I have a T-Rex 450XL HDE (about to be upgraded to CF/eCCPM Al Head). While building it I thought it was very odd to require balancing the paddles. With the flybar centered and even on both sides (measured with calipers) the paddles always fell to one side. I was able to get them apparently balanced by adding tape to the light side. I thought to correct the issue during initial spin up testing. I had a wide RPM range vibration and noted the flybar tendancy. After balancing it with tape the vibration was greatly reduced (I should have used a scale or something accurate to do a better job),

Jermo

[flyinfool]

My very simple rule is;
If it spins, balance it.

I have seen paddles that were dead perfect down to .005 gram and I've seen "Identical" paddles that were different by 5 grams.

[Jermo]

is there a preferred way to balance them? seems silly to add tape, I'd almost prefer to drill small holes in the light one or figure out where it's off and trim it....just gotta keep in mind the aerodynamics of it.
Jermo

[flyinfool]

On the little helies I just use clear Scotch tape. It generally does not need much and you will never see it later. On paddles I do not wory about spanwise CG, but I do add any tape near the CG of the the paddle.
I use a powder scale to weigh the paddles, tail blades or other small parts. a powder scale will read to 0.1 grain which is .006 gram.

[robl]

I've been trying this on my 450 just now. read a file that said to turn the heli on its side and with spur gear and swash disconnected, you should be able to spin the head with no blades and see which paddle is heavier, unfortunately, it is not working on the trex. I don't know if the bearings are bad, or the main shaft is bent(doubt it as its a brand new mainshaft), but this thing just isn't balancing out. Anyone have any ideas? I don't have a gram scale.

[slikrx]

I've been trying this on my 450 just now. read a file that said to turn the heli on its side and with spur gear and swash disconnected, you should be able to spin the head with no blades and see which paddle is heavier, unfortunately, it is not working on the trex. I don't know if the bearings are bad, or the main shaft is bent(doubt it as its a brand new mainshaft), but this thing just isn't balancing out. Anyone have any ideas? I don't have a gram scale.
I can think of one way, but you'll need to remove the flybar assy and you'll need an accurate caliper that can measure (accurately, to +/- 0.001") the distance between your paddles.

If you have that, the here we go:

With your head assembled, measure the distance between your flybar paddles to the nearest thousandth of an inch. (0.001") One note: your paddles should have the same number of turns when screwed onto your flybar.

Remove your flybar from your heli.

Reassamble the flybar off your heli. Make sure you get the identical spacing you did when you measured it on your bird. Mark the exact center of the flybar.

Next, place the flybar on a metal rod, just like in Finless' "blade balancing 101" video.

Place the flybar assy so that your measured centerpoint is exactly on top of the metal rod. Ideally, your flybar will balance and both ends will be in the air.

If not, add small amounts of clear tape to the light paddle until they balance.

Disassemble this, then reassemble it on your heli, making very sure that you have the paddles the same distance apart, and that the flybar is centered on the head.

[robl]

yes, I could possibly do it that way, but if its slightly off,it won't work. Might make sense for me to just get one of those high point balancers. for 25 bucks, its a hell of a lot cheaper than a gram scale at 80 plus.

[slikrx]

yes, I could possibly do it that way, but if its slightly off,it won't work. Might make sense for me to just get one of those high point balancers. for 25 bucks, its a hell of a lot cheaper than a gram scale at 80 plus.
If you don't have a pair of vernier calipers of a dial/digital caliper, then yeah, getting a balancer would be cheaper, but I'm not sure how you would attach a flybar assy (or just the paddles) and get it centered...

Goood luck, however you get it done! :D

[Seeker]

For sure get a set of calipers. You'll use them for so many things in this hobby. You can pick a set up for around 15 bucks or so at one of the discount tool shops.

Once you balance your paddles (I weigh them) and assemble your flybar on the head. Measure the flybar with your new calipers :) to get it exactly centered on the head. Count the number of times you turn the paddles when you put them on. Many paddles have a slot you can see the flybar come through and you can use that. Then use your new calipers :) to measure from the head to the paddle to make sure they are exactly the same. Move the flybar on the head to make the very small adjustments at this point as you wont be able to turn the paddles.