darticus

Do people balance their planes and does this help with doing rolls? Is there a method to doing this? Thanks Ron

rmenke

My Feedback: (13)

darticus:

Yes, ballancing a airplane is critical to the way the plane will fly, and not just the CG. Many do it with their fingers, some create strange looking devices, some purchase devices called CG machines such as the one sold by Great Planes. A short distance between CG locations can make a great difference in how the airplane will fly. The farther back you move it the more pitch sensitive it becomes. Too far forward, it becomes a snapper. Best to locate the CG per manufacturers recommendations and then modify to suit your flying. Lateral ballanceilng is also needed to make the bird a better flyer. Say you have a hevy wing. The plane will tend to fly toward the heavy wing so you use your radio trim to compensate. Now it will fly level as the ailerons compensate for the heavy wing. The pros will take it home and ballance the wings correctly. This way, the plane flys ballanced naturally and does not require corrections during a flight that is being judged, or at least not as many. Exhibition pros will change CG locatlions between flights to suit what type of routine they plan on doing the next flight. Ever see a airplane fly backwards. Yes, is part of a routine Chip Hyde does that seems impossible, but yet he flys his Doublevision backward about 15-20 feet, changes direction and continues, all within about 5-6' from the ground. This can be a long long subject. Best you get a GP CG machine and follow recommended CG localtions to start with. In short order you will find out how necessary a streight airframe is, and how to create a streight one. ENJOY

altavillan

My Feedback: (1)

For 3D type flying I just pick mine up around where wing spar is. I've sorta learned that balanced just aft of the spar usually makes for a neutral plane. That will be around 36% to 42% of the cord. Then I fine tune till walls are brisk and or it will land without flopping.
For Imac and easy landings somewhere around 32 % to 36% of the cord

darticus

Thanks for all that great info. I'm gonna look for the CG machine. Would like to see how to balance from side to side. Maybe put two nails in the fuselage front and back.
With the small foamies I make maybe this balancing would help.
http://www.rc-airplane-world.com/bal...airplanes.html
I did mean side to side. I also wanted to know where the center of gravity should be? Is there a true spot? Where on the fuselage and wing do you have the CG? Apparently you could make the center of gravity anywhere by moving the plane innards but where should it be? Thanks Ron

jumper666

darticus, as others have indicated, balancing is a MUST not an option. Someone once told me, "An acft with too far aft cg flies only once. An acft with cg too far forward flies badly."

jzrf6c

An easy way to balance a plane "side to side" is make a loop of string around the prop and then thread the other end of the string through the top hindge in the rudder. Now tie off above the rudder. Leave enough string so that you can hang the plane or have someone hold it while you add weight to the ends of the wing to balance the plane "side to side".

DNCrosby

I've had no problem balancing the GP YAK 55 3D Park Flyer EP ARF, but I've tried to make it more stable at high speed... to no avail.. it starts bobbing up and down, during dives, or at max thrust. I've tried adding balsa leading edges to the elevators to reduce turbulence (They come squared off from factory), my next attempt will be to stiffen the hinges with more tape on the ailerons, and see if that helps. Any other ideas ?

-Derek

altavillan

My Feedback: (1)

I fly mine to check lateral balance (which wing is heavier). With it trimmed to fly flat upright I roll it inverted. It will lean to the heavier wing. I also do power off slow stalls. The heavy wing falls first. Then if it tends to want to droop a wing I'll add tape on weight till it gets neutral either way. If I'm happy with the results I'll drill off some weight from the heavy wing or add some weight to the light wing. Keep in mind some slight wing dropping will occour due to the torque from the propeller. To verify, I'll also weigh the wings and wing tips to make sure one wing is actually heavier. Note, the motor is set with right thrust offset. That puts a little bit of extra weight to the left side. So I try to mount the rx and sc on the right side to compensate.

altavillan

My Feedback: (1)

If it's bobbing up and down at high speeds I'd guess the plane is flexing in flight, and will soon explode on you. Try slowing down or put a prop on with less pitch.
A plane that is balanced too far aft will have stability issues at almost all airspeeds but more when flown slowly. A too far forward cg will cause an airplane to loose airflow (stall) over the wings and tail in high speed manouvers but should fly straight with out problems.

DNCrosby

Hopefully not, it's foam, so it flexes quite well, and it's a high pitched flutter, like turbulence, but it only occurs during steep dives during 50% or more throttle, and during level flight when engine is cool, and batteries are fresh. It's still not something that is very "scale" or desirable visually. But it might be the nature of the beast... just wondered if anybody with that plane had experienced this, and had corrected it successfully.

stanairman

My Feedback: (93)

does anyone have davepatrick biplane i have a new 40 ultima it came with instructions but no where does it say where the cg is does anyone have the correct measurement thans stanairman

Eganwp

My Feedback: (1)

haha, close but not quite. It goes:
"A nose heavy plane flies poorly; a tail heavy plane flies once."

Eganwp

Not entirely true however, as I fly my 3D planes extremely tail heavy when wanting good harriers and hovers. All depends on your skillz and setup!