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View Full Version : Lateral balance and CG on HL Yak-55?


meatball
12-28-2005, 04:17 AM
Hi, I recently just finished (as of 1 hour ago) a HL Yak-55 I got a while ago. I have an Esskay 400XT as motor, TowerPro 10 AMP ESC, and 1300 mAH Electric Power 8C battery. Because the battery is alot more sqaure then the TP packs which are much longer and flatter in width, I mounted the battery on the side of the fuse, which also helped place the CG on the spar, because I dont think it would balance there with the battery in the slot, I had to move the front of the battery about an inch in front the slot, and put the receiver on the fuse side right on the spar (micro 555).

For it to fit in there, I'd have to enlarge the hole by at least twice its size. Unfortunately mounting the battery on the fuse side has thrown off the lateral CG to that side. How important is this? Also, are you guys putting the CG right on the spar?

lindart aviation
12-28-2005, 12:00 PM
It should be laterally balanced. Spot glue a small screw eye in the fuselage at the c/g and hang it from a wire hook. Some are easier to do inverted.Afterward cut it loose..or just leave it in for the 'remote' possibility of future repairs. art

Sky Sharkster
12-28-2005, 02:52 PM
To Meatball, I have to agree with L.A., the lateral C.G. is very important, especially in a 3D model. You won't notice it too much in level flight when the aerodynamic forces will overcome weight offset but as soon as you try high-alpha, low-speed maneuvers it will "fall off" to the heavier side, every time. Just as you can't cure (for example) a tail-heavy condition by applying "down" elevator, a rudder or aileron deflection won't compensate for lateral weight offset.
My suggestion would be to place weight on the lighter wingtip until it balances, glue in place. Good Luck! Ron

k-vette
12-31-2005, 04:19 AM
I prefer to cut some of the fuse and place the battery in the center. If need be I add a flat piece of cf on the bottom of the fuse, below the battery to keep the plane stiff. That's only if I had to remove a lot of foam to fit the battery. On mine I think the CG is probably closer to 1" behind the spar. You may have to experiment a little to see where you like it.