Making it SMOOTH?????

[loewermx]

After reading a few other posts and watching some truly awesome vidoes (you know which ones), I am wondering a few things.

How exactly do you balance the main rotor head? Tail rotor? I did a test flight tonight with the Maxi Joker and I have a very VERY little vibration that I will need to find. I plan on finding a gram scale tomorrow so I can weigh most everything. What else can I do to make sure everything is perfect?

Scott

I did post this on the otheRR site so if you are reading this twice, sorry. I just know that there are different people that frequent each site.

[AZ ChopperCam]

To me there are 2 levels of smooth.

1. Underslung smooth

2. Front mount smooth

Number 1 is much easier to attain. Basic blade balancing/tracking and you're done.

Number 2 takes work. It's tedious and experimental. Much trial and error. Also one thing I have learned is just when the ship looks like it's running smooth a new vibe works its way in. You have to tackle each vibe separatley. Sometimes you remove one only to find that it created another.... grrrrr!

I've come to the conclusion that if you want liquid smoothness you'll want a metal rotor head. Not to say plastic won't work. It does and I have about 13 hours of flight on my stock plastic hub, but over time they loosen up.

Some folks don't give much thought to the paddles. I weigh mine and balance them. If I find a heavy one I will drill a 3mm hole from the outside end to remove material. They are usually within .1 gram but it's all in the details.

Flybar weights help too... not just for smoothign out the cyclic but for adjustability. You can slide one weight in or out a little and test fly. Sometimes I have found that one weight needs to be a couple mm off to one side or another to get dynamic balance.

Balance of the blades is of course very critical. balance spanwise and weight wise to within .05 grams. If you have a .1 gram scale just get them to the point that they flicker the same amount to the next tenth.

I weigh each part of the rotor head. Mixing arms and washout arms are weighed and verified to be of the same weight.

One thing that does make a difference from flight to flight is blade grip tightness. Some days they like to be tighter than others... why? I dunno. Must have something to do with temp/air density as the blades must lead/lag differently.

All this stuff is completely unnecessary for a sport or 3D machine but if you want a liquid smooth ship for AP/AV you're gonna have to buckle down and tweak, tweak, tweak.

The reward is when you lift your ship up into a hover and it just sits there. not even so much as a .020" buzz in the tail or skids. That's nirvana.

[askman]

for small heli, I use 0.01gm scale. I bought a cheap ebay 100gm scale and measure everything I can on it. (in pair of each part. these scales are accurate enough for comparison, but I would not trust them for absolute) larger mains are harder, and you need bigger scale. (I have access to .0001gm 200gm scale at work, so I use that for most of my blade)

just doing these thing and matching them up helps a lot.

[WMann]

Something that has not been mentioned here that is critical and something that I do to all of my Kyosho Caliber contest machines is dial indicate the rotor head block to the main shaft. I even go so far as to red loctite the hub to the shaft and I never remove the hub from the shaft until it's useable life span has been exceeded. I take the main shaft and just the head block (un-assembled) and put the main shaft in a set of V-Blocks and I keep messing with head block until it has less than a quarter of a thousanths run out. I have never seen any head blocks from any manufacture that will lock down dead nuts on every time. I guess it goes without saying at this point that I indicate the main shaft as not many of those are less those have less than a half a thousanths run out.

Also another thing that will help with vibrations being transmitted to the camera is to run a much softer damper set up in the rotor head. With softer dampers any slight tracking or balance issues are not as severe as viewed by the camera. Plus a softer set up will make the helicopter fly smoother and less jerky.

I hope this helps


Wayne Mann

[loewermx]

Thanks guys, can anyone recommend a place to get a gram scale that would work for weighing things like paddles and such? I would like to find something local (Radio Shack, Home Depot, Lowes, ect...) if possible. That way I could get to work on it right away.

Last night, I did find that the flybar was off about 2mm or so. I know that will cause some vibes. I want this machine as DJ calls it "front mount smooth"

Scott

[peaks view]

:?: Is there a better way to track blades?? How can I tell which blade is off aside from the obvious? I tried color tracking tape, but it is still difficult to tell how close I am.

[catfight]

loewermx,

Try a (large) local cook's supply store. I bought a Pelder model for about $30 that measures down to .1 gram.

[frankos72]

loewermx,

Try a (large) local cook's supply store.

Probably in the phone book as Restaurant Equipment Supply or something of the such.

[Tonystott]

Small scales purchases.
I just bought a 100gram electronic scale that reads to 0.01grams for $AUS50 off Ebay. There were stacks of choices.

Here's a 50g scale (0.01g resolution) with one hour to go for under $10!
http://cgi.ebay.com.au/1-100g-CARAT-SCALES-JEWELRY-DIGITAL-SCALE-w-CAL-WEIGHT_W0QQitemZ160029272064QQihZ006QQcategoryZ340 88QQrdZ1QQcmdZViewItem

[lakespinner2]

I have an older model "ibal 201" scale (1/100th gram and 200 grams max weight) that works pretty well. I tried googling it for a local bricks and mortar store but the only things that came up were web stores, which is where I got mine. It works well for blades though.

If you really get into balancing blades and have a Koll balancer, I hear you need a scale to weigh the koll + the rotor blade at the same time, probably need 3 to 500 grams max weight, I haven't weighed the koll to see what it weighs. When I bought mine a while back the price really shot up on the .01 gram resolution scales for the higher weight capacity models. For the balancing I do, the ibal201 works fine.

[k2pilot]

don't forget the cg of the blades, that can often vary quite a bit. i always like the scales that attached the two blades to the pivot point and balanced them that way.

[AZ ChopperCam]

yes, high point balancing of the blades is a good thing to do also.

[aramsdell]

:?: Is there a better way to track blades?? How can I tell which blade is off aside from the obvious? I tried color tracking tape, but it is still difficult to tell how close I am.

I track my blades indoors initially in my basement. Most of my blades have white tips. Try this ....Color the tip of one blade with Red or black sharpie marker. weight down the skids with a board or similar to prevent a flyaway. Shine a flashlight at the tips of the blades from the side. Run the heli up to hover speed. You should be able to spot the low blade easily. As always SAFETY. Face shield if you've got it.

[askman]

I always match CG first, then use scale to match the weight by adding tape to the CG. works great.

[Crjbenny]

I got curious about just how precise I could get the blade balance so I went to a local pharmacy and used the scale they had that would go all the way to the ten thousandths of an oz. or gram I belive it was.

I had to add a few more slivers of tape to make the balance perfectly.

[Edge111]

While trying to find a vibration on my maxi joker, I found one blade grip to be 0.5g heavy. I was wondering where the best place to remove material from is. this got me thinking....

When you balance blades you find and balance the CG first, then the overall weight is adjusted by adding weight to the CG of the light blade.
what about the grips, where do you add (or remove) weight??
shouldn't they idealy be balanced as part of the overall blade assembly, thus moving the CG to nearer the root of the blade, then adjusting the weight by adding tape to this new CG.

Would that work out to be the same overall as balancing the blade in the normal fashon, then finding the CG of the grip on it's own and adding (or subtracting) weight here???

Anyone's thoughts?......

[Wbird]

I never used to spend much time on my flybar, until I started in AP. The way I do it now is centre the flybar rod in the cage with a digital caliper, pretty much exact. Then install the blades the recommended distance. Again use the digital caliper to measure from the cage to a reference point on the blades. Then I run up the heli without mains or tail blades. Better still if you remove the entire tail rotor hub from the shaft to guarantee the tail will not interfere. If there is any sort of vibe I mark one flybar paddle with a pencil so it doesn't affect weight and it is removeable and give it a turn in or out and run again. If it gets worse I went the wrong way, better, try another turn. Another thing I overlooked in the beginning is the flybar tracking. USE A PITCH GUAGE every time you adjust the paddle. I used to eyeball and it always worked good enough for the flying I do. Basic flight, beginner 3D, etc. but when doing AP "eyes" are not good enough. Once this runs smooth (mainshaft should look solid not fuzzy on edges when at full rpm) everything else is up to blades. I have on occasion had small vibes in heli and tweaked one paddle in or out a turn or 2 and cleaned it up even with all blades in place.