View Full Version : CG Question
04-26-2011, 01:38 PM
Hey guys I have the edge 540 .60 from seagull. the manual says CG is about 100mm from LE at fuse. I have mine set at 90mm. The plane flies really well and lands quite easily, however it does not fly well at low speed and it doesnt go into a hover very well at all. it feels like I have to fully deflect the elevator to fly slow and it just feels nose heavy. My question is, will I need to move the CG further back then the manual sugests or right at 100mm? I am just hesitant to try as I understand tail heavy planes can be hard to land sucessfully:yikes:. If anyone has a similar setup, and experienced similar problems, Id love any advice, thanks.
P.S. Engine is os 95ax
04-26-2011, 02:08 PM
As a start, use the manufactures recommended C of G (it's almost always correct). Move your C of G back another 10mm to the recommended 100 mm and ensure that your measurement is truly taken from the leading edge, probably at the root; you're correct that you want to avoid flying a tail heavy aircraft. IMHO an aircraft, whether used for 3D, IMAC or simply Sunday fun flying, should never be tail heavy. It's a common fallacy that to properly 3D, you need a tail heavy model; it may hover great, but there’s more to flying than hovering. To check the correct C of G location, fly at 100 mm back from the leading edge and, at a safe altitude, roll the model inverted and release the sticks. If the model climbs, you're tail heavy, if the model descends rapidly, you're nose heavy, but if it descends only gradually, IOW, you require only slight down elevator to keep the model in level flight, you're probably close to the correct C of G location. After this basic test, you can tweak (in very small increments) the C of G to suit your flying style and comfort level.
04-26-2011, 02:29 PM
I just reread your post and noted that your flying your model with an OS .95 AX. This motor is considerably larger than your ".60 size" kit designation so you are already working with a heavier hunk of metal on the front end. Not a problem really, except you might have move more weight to the back, whether by shifting equipment or adding tail weight. I have a Hanger 9 .60-.75 Ultrastick that I powered with an old OS .90 FSR and had to add almost three oz of tail weight, after shifting the receiver, batt and servos to the back of the equipment box, to bring the C of G to specs ;).
04-27-2011, 01:54 PM
The recommended engine size said 61-91 and the guy said it was more of a 90 size plane but whatever, Ill move it back another 10mm. thanks for the advice.:)
04-28-2011, 07:28 PM
Flew again yesterday with cg at 100mm which made a nice difference. the plane feels more 3D capable and flies better at low speeds. the most notable difference was landing as it didnt want to glide forever and I could better predict how much runway I needed.:)
04-28-2011, 09:34 PM
Hey Edgefiveforty, that's great! Wishing you a safe and enjoyable R/C season.
04-29-2011, 08:37 PM
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