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solentlife
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Joined: 30 Dec 2010
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PostPosted: Fri Sep 16, 2011 12:07 pm
PostPost subject: Balancing parts / whole of a Trex / Clone
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So lets start a thread describing balancing of the 450 class Trex / Clone machine. Not only the overall CoG matter but also parts and assemblies of the machine.

We all should be good at main rotor blades, I have the threaded shaft and two cones to do mine and works brilliantly.

We can detect whole model balance by suspending by flybar etc. and moving battery accordingly, (funny thing is I find that I get little difference with the range of batterys I have even though there are weight diff's .... )

So how to balance other parts / assemblies ?
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Crashagain
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PostPosted: Tue Sep 20, 2011 7:29 am
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I run a 3400rpm head speed on my 450 V1 and I can honestly say I have never balanced anything on it.
If you keep the slop in the head down and the belt tight and check the bearings often, the heli should be nice and smooth.
I think with the clones it's a different, lower quality bearings, cheap plastic and soft metal bits, tend to let the heli vibrate.
I stand by my moto, you get what you pay for...
Every Trex I have had is super smooth, I had one copterX and I could never get it as smooth.. But it flew. There is a reason they are called clones..

Just my .02
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Trouble
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PostPosted: Tue Sep 20, 2011 10:32 am
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Why do I need to do all this? The factory takes care of that, I don't need to balance my boom or mainshaft bearing blocks or my landing gear, or anything else for that matter, I never had a problem with balancing, and I don't even know what my headspeed is... 'Course maybe the factory where your helis come from don't have Quality Control, and you have to go through all that extra work. Kinda like inferior metals that fatigue and break at the most in-opportune times...like tail boxes. Wink I had 3 Copter Xs', worst P.O.S. out there, EXI is like owning an Avant compared to that.
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Crashagain
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PostPosted: Tue Sep 20, 2011 11:05 am
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I can see balancing blades if you buy the cheap woodies, but other then that I don't see the need to balance anything
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solentlife
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PostPosted: Wed Sep 21, 2011 9:36 pm
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You guys surprise me with the answers.

There are so many online sites that are quoted / pointed to for newbies that go into balancing routines.

Personally ... I only balance the main rotors. I stopped doing the CoG bit as I found it basically didn't move much with battery.

There is a post in my breaking tail-unit thread where one balances his tail units ... now that is interesting to know how !
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Crashagain
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PostPosted: Sun Sep 25, 2011 6:03 am
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Why would our answers suprise you? I mean really, how many things do you really need to balance on a heli to make it fly?
Main blades maybe, if you buy the cheap ones off of Ebay, but other then that, if you center the flybar, and measure the paddles when you install them, what else do you need to do?. Spool it up and go fly..
I think that too many people get overly caught up in the setup, mechanics, and little stupid things to work on then the actual flying part of the hobby.
If you get good stuff, don't waste your money on junk chinese knock off electronics and do it right the first time you will be a pilot and not a mechanic.
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solentlife
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PostPosted: Sun Sep 25, 2011 12:02 pm
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Crashagain wrote:
Why would our answers suprise you? I mean really, how many things do you really need to balance on a heli to make it fly?
Main blades maybe, if you buy the cheap ones off of Ebay, but other then that, if you center the flybar, and measure the paddles when you install them, what else do you need to do?. Spool it up and go fly..
I think that too many people get overly caught up in the setup, mechanics, and little stupid things to work on then the actual flying part of the hobby.
If you get good stuff, don't waste your money on junk chinese knock off electronics and do it right the first time you will be a pilot and not a mechanic.


Suirprised because some posts are advocating not balancing anything. So many of the online pages that we are directed to as newbies in this hobby - have balancing advice ...

I have to say that initially - I fitted blades and flew .. never bothered checking balance. I figured that designers had sorted where to put the gear and that was it. Unlike fixed wing where you have far more influence yourself on CoG etc.
But after reading loads ... I started balancing and checking. Did it make any difference ? Not really that I noticed. Do I still balance blades ? Yes regardless of source.

OK onto cheap chinese ....... knowing various managers / R&D guys in various companies ... respected high end brand names as well .. such as Nokia. I can say without hesitation that Chinese factories are churning out your high priced 'originals' as well as the cheap clones. Did you know that IBM PC's were churned out in Chinese factories for years before Lenovo took over the PC naming ? In fact I know of two brand names that actually KNOW the same factory and production line is producing the clones alongside the originals. Be that as it may.
Let us take cheap blades as an example. I buy glass fibre multi-packs of cheap blades of ebay ... I check all for balance ... and find that they are so close to each other in the sets .. a small sliver of clear tape is all that's needed ... in fact putting the contrast tape on for tracking UNBALANCES the blades ... making it necessary to add clear tape or contrasting on other.
Without those cheap chinese items - I would find it difficult to sustain the costs of heli models. Honest answer.

Wink
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Burgess
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PostPosted: Fri Mar 30, 2012 1:13 am
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It is the responsibility of every UAV pilot to ensure that whatever they decide to fly, is mechanically fit to make that flight. Ergo, if there is an imbalance that results in a malfunction and a third party sustains damage, it is the pilot that is liable not the manufacture of the helicopter.

Not everyone can afford to purchase a brand new Align Trex 450, or the cost of having it professionally maintained for them.

The number of those purchasing so-called clone t-rex 450s, probably outnumber those who can afford to purchase an Align Trex 450.

Thus, for those of modest income, the knowledge of how to set-up and maintain their machine should be self evident.
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tombo242
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PostPosted: Fri Mar 30, 2012 2:52 am
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I go for balancing every time. Very rarely do I find anything balanced to my satifaction - but then I like to imagine that I am going to fly in the machine and service it accordingly.

I recently had a small prop on an indoor plane that was about the same size as a 450 heli tail rotor. It had a slight imbalance and threatened to shake the motor off of the fire wall. A little clear tape and no problem - smooth running. Makes me wonder if some of my early tail failures on the helis were due to unbalanced tail blades!

Tom.
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chopper54
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PostPosted: Sat Mar 31, 2012 2:27 am
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I balance new main and tail blades before use. Its not exactly a mammoth task. Vibration can effect the gyro.
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Burgess
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PostPosted: Fri Apr 20, 2012 8:46 am
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Tracking contrasting tape:
solentlife wrote:

in fact putting the contrast tape on for tracking UNBALANCES the blades ... making it necessary to add clear tape or contrasting on other.
Wink

First weigh the blades, then find the centre of gravity of the heaviest blade, copy that CoG mark on to lighter blade and adjust weight distribution till it balances on that CoG mark.
Then mark off placement for tracking tape about 25mm in from the tip using try square. Add identical lengths of contrasting tracking tape to the blades and check for CoG again they will have moved, mark the new positions.
Then fix together and check for balance, if one is heavy add clear tape to the lightest blade centred on the new CoG position.

I use red and blue tape and when they are tracking in the exact same plane of rotation, their colours merge to give the illusion of purple. Cool
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tombo242
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PostPosted: Thu Jun 21, 2012 5:50 am
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Question on tracking:

I have never found that my blades need tracking when the heli is correctly set up. It seems to me that having gone to all the trouble to set up and level the swash, washout block and match the blades for the correct pitch at low, mid & high stick, any need for further adjustment shows that either you have a twisted blade or your set up was not correct in the first place.

Aren't you resetting the pitch of a blade that you have theoretically already set correctly? How does it look now at mid-stick for zero pitch?

Tom.
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Crashagain
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PostPosted: Thu Jun 21, 2012 12:22 pm
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Tom, your very right about setup. With all my heli's I have never had an issue with tracking. Setup one blade at zero pitch and then rotate the head and make the other blade the same and it's a win win..
However when I have run the woody blades on my 450's sometimes I would have one that would be a tiny bit out of track when the heli is in a hover, even after doing all the setup correctly.
I think this is caused from the wood in the blades, one being softer then the other thus allowing it to rotate in a plane slightly higher then the other blade. My rule has always been if they are a little out of track, then bring the high blade down, this way you don't damge the + & - overall pitch that you setup earlier.
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tombo242
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PostPosted: Thu Jun 21, 2012 5:56 pm
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Thanks for that Crash,

I find that some blades have a very slight twist not discernable by sighting down the blade. I like to clamp them at the root and check down the blade with the pitch gauge against a 0º marker line. If no change at any point it's good to go. If not then there will be a tracking issue unless it has a brother in the same state.

It's just one part of my "Check the New Packs of Blades" routine. Time consuming - yes, but very successful. Of course, being retired I do have more time than money so that's not an issue for me. (Keeps me away from the "Honey Do . . . ?s" for a while as well.)

Tom.
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admiral
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PostPosted: Fri Jun 22, 2012 3:00 am
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Hi Guys,

I must be a belt and braces man, I level the swash and match the link lengths. but I still always check the blade tracking, only takes a minute to check. I'm converting my fleet to FBL and as part of that replacing the Blade Grip links with turnbuckles that makes adjusting tracking even easier.
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