Some questions on cg
08-30-2002 | 12:01 AM
#1
Some questions on cg
Hi all
I'm looking for some thoughts on balancing an arf. This is my first arf so I am a little lost without a plan. The manual states that the initial cg should be set to 3 1/4 inches from the leading edge until the plane appears to be level. My problem is determing exactly what they mean by appears to be level. There is no datum line to aid in leveling the plane at the cg and the fuse is not flat on either the top or the bottom. I initially tried taping a small bubble level to the bottom of the fuse at the balance point. However even though the wing and fuse look level the stab seems to have a positive angle of attack. I would appreciate any ideas on how to get the plane properly balanced.
Thanks in advance
K
I'm looking for some thoughts on balancing an arf. This is my first arf so I am a little lost without a plan. The manual states that the initial cg should be set to 3 1/4 inches from the leading edge until the plane appears to be level. My problem is determing exactly what they mean by appears to be level. There is no datum line to aid in leveling the plane at the cg and the fuse is not flat on either the top or the bottom. I initially tried taping a small bubble level to the bottom of the fuse at the balance point. However even though the wing and fuse look level the stab seems to have a positive angle of attack. I would appreciate any ideas on how to get the plane properly balanced.
Thanks in advance
K
08-30-2002 | 06:47 PM
#2
Some questions on cg
Hallo!
It is not that difficult...itīs really very easy to balance any airplane!
just hold your fingers under the wing at the appropriate place... if the airplane drops the nose slightly itīs okay! if the airplane just hangs in balance or drops itīs tail then its too tail heavy...If this is your first airplane and your first try att R/C ....get some help from a club with an instructor! Otherwise you will crash instantly !
Good luck!
Jan K
Sweden
Flying for 27 years!
It is not that difficult...itīs really very easy to balance any airplane!
just hold your fingers under the wing at the appropriate place... if the airplane drops the nose slightly itīs okay! if the airplane just hangs in balance or drops itīs tail then its too tail heavy...If this is your first airplane and your first try att R/C ....get some help from a club with an instructor! Otherwise you will crash instantly !
Good luck!
Jan K
Sweden
Flying for 27 years!
08-30-2002 | 07:40 PM
#3
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From: d, AL,
Some questions on cg
I'm a second-generation newbie, but here's what I do.......
Mark the exact balance spread, or point, on the wing with masking tape.
I use two dowels glued into a poly base (pencils with the eraser pointed up are great if they're long enough), but wood or anything will do.
Place the plane on the dowels (upside down for a low wing, right side up for a high wing.
Get it to appear to balance somewhat by moving the plane fore and aft on the dowels.
When it looks close, hold the plane at that position and put a small bubble level on the horizontal stabilizer.
Was it correct?
If not, remove the bubble level (extra weight) and move the plane fore or aft and hold or brace the H-Stab and put the level on again.
Looks good now, yes?
Look at the dowel position on the recommended CG marks you put on the wing.....Are they within the range? If so, you are horizontally balanced, if not, add weight, nose or tail, or move batteries/servos until it balances (best option!)
I know this is probably the tedious method, but it has worked for me. You could buy a commercial balancer but still it only replicates the dowels.
I've tried the sling, too, but was never really sure. I know this method works.
Anyone else?
Mark the exact balance spread, or point, on the wing with masking tape.
I use two dowels glued into a poly base (pencils with the eraser pointed up are great if they're long enough), but wood or anything will do.
Place the plane on the dowels (upside down for a low wing, right side up for a high wing.
Get it to appear to balance somewhat by moving the plane fore and aft on the dowels.
When it looks close, hold the plane at that position and put a small bubble level on the horizontal stabilizer.
Was it correct?
If not, remove the bubble level (extra weight) and move the plane fore or aft and hold or brace the H-Stab and put the level on again.
Looks good now, yes?
Look at the dowel position on the recommended CG marks you put on the wing.....Are they within the range? If so, you are horizontally balanced, if not, add weight, nose or tail, or move batteries/servos until it balances (best option!)
I know this is probably the tedious method, but it has worked for me. You could buy a commercial balancer but still it only replicates the dowels.
I've tried the sling, too, but was never really sure. I know this method works.
Anyone else?
