CG Balance for large jets
07-05-2012, 09:52 AM
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CG Balance for large jets
I recently came across a nice product which aids in balancing our larger jets. It's the Husky Hangs All, found at Home Depot. I use the suspended method and these straps have proven to be very easy and secure to use. The velcro straps adjust to fit almost any size fuse. For those not familiar, the photos should be self explanatory. The plumb bob indicates the location of the C/G, which should be right at the back edge of the inspection plate.
David S
David S
07-05-2012, 10:04 AM
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RE: CG Balance for large jets
David,
You can improve that by running your suspension lines through a pulley. It would make the rig a little more sensitive. Less friction on the lines
Bob
You can improve that by running your suspension lines through a pulley. It would make the rig a little more sensitive. Less friction on the lines
Bob
07-05-2012, 11:17 AM
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RE: CG Balance for large jets
Matt
It should be one line going through an eyebolt or a pulley. Then it would be able to pitch up and down to achieve balance.
It won't move if he has two separate lines.
It should be one line going through an eyebolt or a pulley. Then it would be able to pitch up and down to achieve balance.
It won't move if he has two separate lines.
07-05-2012, 11:39 AM
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RE: CG Balance for large jets
Matt,
It is one continuous line from front of fuse to back, threaded thru an eyebolt in the ceiling. The excess line is fed back thru the eyebolt to lift the fuse to height and and to make it easier to adjust the fuse level. as such, the fuse is balanced evenly below the central point of the eyebolt. Drop a plumb line from that central point and you get your point of balance.
Bob,
Yes, a pulley does make it more sensitive, I've tried it in the past, but found the simple eyebolt gives results close enough for my needs.
Oli,
Will do.
David S
It is one continuous line from front of fuse to back, threaded thru an eyebolt in the ceiling. The excess line is fed back thru the eyebolt to lift the fuse to height and and to make it easier to adjust the fuse level. as such, the fuse is balanced evenly below the central point of the eyebolt. Drop a plumb line from that central point and you get your point of balance.
Bob,
Yes, a pulley does make it more sensitive, I've tried it in the past, but found the simple eyebolt gives results close enough for my needs.
Oli,
Will do.
David S
07-05-2012, 03:49 PM
#8
RE: CG Balance for large jets
For airplanes that large, you can also use the weight-on-wheels method. All you need is a ruler, a scale, and a calculator (or Excel spreadsheet). It gives you an *exact* result and also gives you the aircraft weight at the same time.
Bob
Bob
07-05-2012, 03:53 PM
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RE: CG Balance for large jets
ORIGINAL: hooker53
David, Did you mold that 21 up or?? Very nice looking detail. I want to do a set of molds for a small JC Bee sized 21 this winter.
David, Did you mold that 21 up or?? Very nice looking detail. I want to do a set of molds for a small JC Bee sized 21 this winter.
David S
07-05-2012, 04:46 PM
#10
RE: CG Balance for large jets
ORIGINAL: Meesh
It should be one line going through an eyebolt or a pulley. Then it would be able to pitch up and down to achieve balance.
It won't move if he has two separate lines.
It should be one line going through an eyebolt or a pulley. Then it would be able to pitch up and down to achieve balance.
It won't move if he has two separate lines.
BTW, Nice bird David. [8D]
07-05-2012, 05:00 PM
#11
RE: CG Balance for large jets
ORIGINAL: rhklenke
For airplanes that large, you can also use the weight-on-wheels method. All you need is a ruler, a scale, and a calculator (or Excel spreadsheet). It gives you an *exact* result and also gives you the aircraft weight at the same time.
Bob
For airplanes that large, you can also use the weight-on-wheels method. All you need is a ruler, a scale, and a calculator (or Excel spreadsheet). It gives you an *exact* result and also gives you the aircraft weight at the same time.
Bob
+1 I've got a spreadsheet that i made to use to balance all my models over 20-25lbs. It gets you down to as accurate as you want (tenth or hundredth's of an inch or pound), and even works out well for determining how much ballast is needed in certain positions to get the model at the desired balance point.
