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CG balancing problem

Old 07-02-2015, 09:11 AM
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tazzzz
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Angry CG balancing problem

Im trying to balance my GSS, problem is I get 2 results. I have one of those blue balancers(cant remember the name,a popular one). If I balance right side up,,I get nose heavy balance, If I balance it upside down I get a serious tail heavy reading. The balancer is completely free of any resistance. Im not trusting any of this. Has anyone had this problem? Or is there a better balancer out there. It seems to work well on my lighter planes. VERY frustrating!

THX a million---TAZZZZ
Old 07-02-2015, 10:08 AM
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Greg Wright
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https://www.youtube.com/watch?v=tfXTyz8w7JY
Old 07-02-2015, 10:37 AM
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tazzzz
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Thanks Greg, but Im really not interested in any Hi-tech balancer. Just the basics. TAZZZZ
Old 07-02-2015, 11:23 AM
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Greg Wright
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Have it your way then.

I also have one of those blue Aluminum $230.00 BS balancers also that i will never trust again.




Last edited by Greg Wright; 07-02-2015 at 05:05 PM.
Old 07-02-2015, 11:37 AM
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JohnBuckner
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Just the basics' I have no clue as to what a GSS is but assume it is some sort of low wing airplane. typically if you try to balance a low wing right side up there is to much mass above the balance pivot and any balance point derived at like this is suspicious at best.

Here is the bottom line using your finger or any kind of mechanical device there must be more of the airplane mass below the fingers or contact points on the device. This assures positive stability which must be in place or you will never be able to acheve an accurate actual balance point.

John
Old 07-02-2015, 11:49 AM
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Greg Wright
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John,

I think it's a Great Planes Super sportster.
Old 07-02-2015, 11:56 AM
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tazzzz
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yesssir,,it is a Giant super sportster,,,,so then I should trust with balancing upside down. I just want to be sure before I fly. What confuses me is that the balancer claims that it can be in either position.

thx for the info TAZZZZ
Old 07-02-2015, 12:09 PM
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JohnBuckner
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Yes Tazzzz you are welcome and absolutely, that airplane is best checked upside down.

Greg I have been so tempted to Pop for the Xicoy balancer system for some of my stuff it would be such a joy. Not to long ago I bit the bullet and spent the big bucks for the DreamWorks Xicoy electronic retract and brake system for my little Boomerang Nano. What a joy anti lock brakes can be dang even makes this old duffer look good.

John
Old 07-02-2015, 02:49 PM
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chris923
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Originally Posted by Greg Wright View Post
Have it your way then.

I also have one of those blue Aluminum $200.00 BS balancers also that i will never trust ag



Why don't you like this balancer?
Old 07-02-2015, 05:11 PM
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Greg Wright
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Chris for me personally it just wasn't worth the $ 230.00 i spent on it.

It ended up being very unstable and awkward for one person to use.

It also didn't give me a very accurate CG setting.
Old 07-02-2015, 08:00 PM
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chris923
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Originally Posted by Greg Wright View Post
Chris for me personally it just wasn't worth the $ 230.00 i spent on it.

It ended up being very unstable and awkward for one person to use.

It also didn't give me a very accurate CG setting.

Greg thanks for the info, now I can avoid that balancer.
Old 07-03-2015, 03:08 AM
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Here is my homemade balancer with measurement arms. For this plane my target balance point is 3.25". I set the arms at 3.25", set the plane in position and then move the arms out 1/8" so the plane is not touching the arms. In this case the plane was nose heavy. See weight on horizontal stabilizer. I moved the wing forward to balance. Now it is slightly nose heavy. Will check it again before first flight.
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Last edited by ETpilot; 07-03-2015 at 03:25 AM.
Old 07-03-2015, 04:31 AM
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Top_Gunn
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You can make a Vanessa rig out of stuff you've probably already got (maybe $10 at Walmart if you don't). Balances any plane, upright or inverted. Dead accurate and easy to use.
Old 07-03-2015, 05:55 AM
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The balancer didn't lie. You can balance planes right side up or upside down. It depends on the airplane. High wing right side up low wing upside down. You balance one way you can't double check the other. Kinda like pushing a rope
Old 07-03-2015, 06:57 AM
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Hi!
Come on guys! The best and easiest way of balancing a plane is using the your fingers!
Been doing so since I started flying R/C 40 years ago.

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Old 07-03-2015, 09:22 AM
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Rodney
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What you say is technically impossible. There is only one CG location on any object, regardless of it's position. The CG does not move when you balance inverted versus upright, it always stays in the same exact location, a 3 dimensional location.
Old 07-03-2015, 09:36 AM
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JohnBuckner
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Originally Posted by jetmech05 View Post
you can't double check the other. Kinda like pushing a rope

Man I wish I had thought of that what a perfect illustration of trying to balance the wrong way for the wing configuration.

For those who may ask about a mid wing airplane: Easy just try both ways and whichever is the easiest to at least come close to being able to let go.


John
Old 07-03-2015, 10:00 AM
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JohnBuckner
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Hi!
come on Jaka! Your claim that the "best and easiest" way is using your fingers. Well now fine however that completely leaves out the individual and the airplane so your claim that there is only one best and easiest method is totally invalid.

For example I will use my self as an example. There is no way I could ever even reach the balance point on both sides with my fingertips from my wheelchair nor is there any way I could ever lift that much weight anyway on my fingertips with some of my airplanes. No sir there are many ways to acheve the goal and its a disservice to diss all methods except what works for oneself.

Threads like this are vary helpful to many and those seeking the various methods that may serve them better than what they were formerly using.

John
Old 07-03-2015, 12:06 PM
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Hi!
I understand that there are some people that cannot do what I say but to most of us there is no problem lifting a 0-15kg model airplane with our fingertips.
What I want to point out is that you do not need any fancy gadgets to balance a simple thing as a model plane.
And further more...I get the impression that some people think that balancing is only done once. Which is certainly not the case.
To have a good (perfect) flying plane you have to villing to adjust the Cof G perhaps many times (moving the servo, bttreries ) untill you get the balnce point as you want it.
And the rule of thumb is to get it as far as back you can without having the plane behave badly in any way.

Last edited by jaka; 07-03-2015 at 12:19 PM.
Old 07-03-2015, 01:45 PM
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JohnBuckner
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Ya sure, lifting a 33 pound ( I suppose that's what 15kg means) airplane with your arms about as far as you can reach and holding it long enough on two pinkies is as unrealistic as it gets and the rushed results at best are compromised.

If this hobby/sport/passion teaches one anything its: One size never fits all. Now don,t get me wrong I have used and still use fingertips almost on a daily basis when people stick airplanes in my face wanting an opinion. I have used and still own almost all the commercial types as well as just the board with a coupe of nails or whatever except that fancy blue one in this thread.

John

No one size never fits all and its a disservice to diss all other methods except what you do.
Old 07-03-2015, 03:26 PM
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Gray Beard
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I get a kick out of anyone using the term BEST with most anything. Good is a better term. I would have loved to see anyone try to CG that Patty 35% Extra I had with there fingers. That one was about 35 pounds. How about last years Prime Cut I built, it was a light weight giant but the sheeting on the wing was so light weight a finger or something like the Great Planes CG machine would break through the wood.
I feel the electronic scales are a lot of over kill for the average builder/pilot but there are so many ways to balance a plane with just cheap home made balancers there is no reason for spending the big bucks. I looked at that nice blue CG machine and shuddered at the price. On a lot of my small models fingers work just fine, on some I have to hang them and use a plumb bob.
This Stick ARF I just assembled and set up CGed perfectly without any lead. I had it sitting on a GP balancer while I moved the gear around and just sat everything on the outside of the plane, marked it then hard mounted the gear.
Whatever works for you is the BEST way.
KISS!!!!!!
Old 07-03-2015, 04:13 PM
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flycatch
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I have one of those $230 CG stands and it works as advertised. In addition to that balancer I also have the smaller version. Tried other balancers but they don't compare to quality or durability. Using fingers only apply to a constant cord wing platform.
Old 07-03-2015, 05:18 PM
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Gray Beard
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Durability?? I have had the tower CG machine for 20 years and it's just plastic. Then again I don't throw it across the shop if I'm upset about something.
The CG is the CG and the wing type doesn't care if I'm using fingers or any other type. I have balanced several Bipes with combination wings.
I think I paid 12 or 15 bucks for the tower machine and it works as advertised too. Then again, so did the two pencils in a wood block. Think that one cost me 10 cents to make.
Old 07-03-2015, 05:50 PM
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rt3232
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Just a comment hear Hi wing center of mas is blow the wing, low wing the center of mas is above the wing, So whether your using your finger tips or some other rig make no difference, and the center of mas does NOT move but the C of G can have a range, depending on the type of airplane. It is just easer to do with the center of mas below the balance points.

But that is just me

Cheers Bob T

Last edited by rt3232; 07-03-2015 at 05:52 PM.
Old 07-03-2015, 06:33 PM
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TLH101
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It tells you exactly how to balance the model in the manual. If you don't have a manual, download it from the internet.

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