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HelicopterAlignOther › adding weight to correct cg
11-30-2007 04:12 AM  9 years agoPost 1
ckd

rrApprentice

Saugus CA

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Why am I having to add weight to get the cg correct?? Are others doing the same thing? The only thing I can think of is my fromeco battery comes in at 3.3oz When I check the cg its just a little bit tail heavy with a half tank of fuel. I've added 1 1/2 oz to the nose to get it just slightly nose heavy.

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11-30-2007 04:17 AM  9 years agoPost 2
dva

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Maricopa, AZ

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Do you have any flight interactions with the CG change?

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11-30-2007 04:27 AM  9 years agoPost 3
ckd

rrApprentice

Saugus CA

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Do you have any flight interactions with the CG change?
If I'm in level flight and I let go of the sticks it wants to climb because its tail heavy. The other thing is on a slow approach it will tend to want to stop and fall backwards if I don't keep pushing forward on the stick.

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11-30-2007 12:45 PM  9 years agoPost 4
Droid

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Deep down in the Southwest- UK

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I guess in a hover it wants to fly backwards as well?? How about you use a little bit of forward trim.....

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11-30-2007 12:52 PM  9 years agoPost 5
copperclad

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NY

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hi
rather than adding weight , look into shifting the weight it has , to correct CG , for instance you might try shifting the battery forward , or getting a larger battery , HTH , dana

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11-30-2007 01:01 PM  9 years agoPost 6
SPB

rrElite Veteran

Athens - Greece

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Yeap usually to correct the CG you either remove weight or re-adjust weight. Adding weight is not a good idea.


Sotiris
myhelis.com Flying Team

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11-30-2007 01:09 PM  9 years agoPost 7
tchavei

rrProfessor

Portugal

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you can easily remove 16.8gr of the tail which will make a significant CG shift since is so far away from the center shaft.

a) replace metal tail control rod with a 2mm carbon one (use threaded endcaps to fit the links 11.3gr weight save)

b) remove horizontal fin and clamp and replace with quickUk boom clamp 5.5gr weight save

that should be more than enough to shift the CG forwards (thats over half an ounce lighter on the tail)

Tony


--------------------
"Perfection and patience usually walk side by side..."

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11-30-2007 01:21 PM  9 years agoPost 8
playfair

rrKey Veteran

Rochester, NY

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Have you picked the heli up by the fly bar to check CG?
The flying characteristics you describe could be cause by other factors, such as the paddles not being aligned correctly.


The sky is our canvas

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11-30-2007 01:40 PM  9 years agoPost 9
copperclad

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NY

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and check to make sure the swash is level

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11-30-2007 03:32 PM  9 years agoPost 10
ckd

rrApprentice

Saugus CA

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Have you picked the heli up by the fly bar to check CG?
The flying characteristics you describe could be cause by other factors, such as the paddles not being aligned correctly.
yes thats how I know its tail heavy and my paddles are level
I guess in a hover it wants to fly backwards as well?? How about you use a little bit of forward trim.....
Throws it off when you go upside down. The swash would no longer be level
Yeap usually to correct the CG you either remove weight or re-adjust weight. Adding weight is not a good idea.
If I got a larger battery that would be the same as adding the weight

I'm only adding 1 1/2oz so its not like a huge amount. If I was to go up to the larger battery by fromeco it would be 3.3oz heavier. Theres not a lot of room to move stuff around.

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11-30-2007 03:47 PM  9 years agoPost 11
copperclad

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NY

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hi
can you post a photo of your machines mechanics , perhaps someone would see another option for you

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11-30-2007 03:59 PM  9 years agoPost 12
Zaneman007

rrElite Veteran

Texas - USA

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My center of gravity is tail heavy with the canopy off and slightly nove heavy with the canopy on. I'm using the Fromeco 5200ma battery, and loving it.

This is an old photo, but the battery location is the same. I have since secured the battery with velcro which is anchored via the fan shroud screws.

Old Guys Rule!

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11-30-2007 07:21 PM  9 years agoPost 13
mont_blanc

rrApprentice

UK

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how about this: (based on your photo)

buy a gyro mount and move the receiver onto that

Then move the battery to where the receiver was.

this should bring the weight closer to the centre of gravity.

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11-30-2007 07:48 PM  9 years agoPost 14
ckd

rrApprentice

Saugus CA

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how about this: (based on your photo)

buy a gyro mount and move the receiver onto that

Then move the battery to where the receiver was.

this should bring the weight closer to the centre of gravity.
thats not my heli you are refering to in the photo. I'll try and get a pic posted. I did move the header tank a little bit closer to center and that helped a little bit

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11-30-2007 07:57 PM  9 years agoPost 15
ckd

rrApprentice

Saugus CA

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here's a pic of my set up

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11-30-2007 09:10 PM  9 years agoPost 16
mont_blanc

rrApprentice

UK

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So if I've read this right you're tail heavy and need weight moved forward?

things I can think of that could be moved forward are:

1.your header tank (mounted on other bearing screw if fuel line allows). this gives you the most flexibility (by sliding around in it's mount)

2. moving your battery in to front of nose frame.

3. slide skids forward

4. move secondary rx to front of nose frame

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11-30-2007 09:18 PM  9 years agoPost 17
ckd

rrApprentice

Saugus CA

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So if I've read this right you're tail heavy and need weight moved forward?

things I can think of that could be moved forward are:

1.your header tank (mounted on other bearing screw if fuel line allows). this gives you the most flexibility (by sliding around in it's mount)
This morning I had it mounted to the rear bolts of the side frames by the skids and that helped moving it up to where it is right now. I'm sure right now if I took the nose weight off thats there ( 1 1/2oz) the heli would be perfectly level. I've always been told you want just a little bit of nose weight to help it track better and all around fly better.
4. move secondary rx to front of nose frame
I thought you need some distance between the two.
3. slide skids forward
good idea. I'll do that next

This is where its at after moving things around and only adding 1/2oz of weight with no canopy

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11-30-2007 11:52 PM  9 years agoPost 18
grimthenoble

rrApprentice

Sunnyvale, California

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dude, just add a little trim and call it good. probably would take two clicks at the most.

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12-01-2007 01:08 AM  9 years agoPost 19
copperclad

rrElite Veteran

NY

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hi ckd

as i understand it , you want it to balance with the canopy on and the tank half full , i would think you could lose the weight you added , put some fuel in , add the canopy and check it then , let us know how it goes , HTH , dana

here's a link to the CG page at Raptor Technique , he shows using the main shaft to find balance , and or use the flybar as mentioned earlier
http://www.raptortechnique.com/cg.htm

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