Attention all you Physicists out there!!!

[Dmerino]

I'm trying to get the formula for Static Equilibrium. I want to calculate the balance of my plane through the cg considering the weight of the components, motor and plane. Any help is most appreciative. Thanks. Dennis

[jperch]

What I do to estimate where the CG will be is to multiply the weight of each major item times its distance from the CG. In front of the CG is a positive distance, behind the CG is negative. For example, if the motor weighs 1 oz and is 3 inches in front of the CG, then it has a value os +3oz in. If the servos weigh 1/4oz and are mounted in the tail (4 inches behind the CG), then they will have a value of -1oz in. When you have all these values, you add them up. If you get to 0, then the plane will balance on the CG. If the result is positive, it will be nose heavy. The idea is to start with the CG point where you want it to be. Then move things around until you get a 0 result.

I hope that helps,
Joe

[dtknowles]

Pick a point of reference, the tip of the nose, the tip of the tail. Find the wieght and center of balance of all the components, motor, battery, wing, tail, fuse, Rx, servos, prop, etc. measure the distance from the point of reference to the center of balance of each of these components. Mulitiply the distance to the center of balance of each component times its weight and add them all together then divide the total by 2 time the total weight and that is the distance from your point of reference to the center of balance.

d = distance from ref. - d#mot. distance to the motor

W = weight of comp. - W#mot. weight of motor

Formula

(d#mot * W#mot + d#Rx * W#Rx .......... + d#Bat * W#Bat)/2*(W#mot + W#Rx .......... + W#Bat) = distance from ref. to C of Balance

Tim

[Dmerino]

Thanks for the info., Tim. I don't understand the formula, however. What does the # sign stand for? Thanks, DennisPick a point of reference, the tip of the nose, the tip of the tail. Find the wieght and center of balance of all the components, motor, battery, wing, tail, fuse, Rx, servos, prop, etc. measure the distance from the point of reference to the center of balance of each of these components. Mulitiply the distance to the center of balance of each component times its weight and add them all together then divide the total by 2 time the total weight and that is the distance from your point of reference to the center of balance.

d = distance from ref. - d#mot. distance to the motor

W = weight of comp. - W#mot. weight of motor

Formula

(d#mot * W#mot + d#Rx * W#Rx .......... + d#Bat * W#Bat)/2*(W#mot + W#Rx .......... + W#Bat) = distance from ref. to C of Balance

Tim

[Dmerino]

Thanks, Joe. That does help. Dennis

What I do to estimate where the CG will be is to multiply the weight of each major item times its distance from the CG. In front of the CG is a positive distance, behind the CG is negative. For example, if the motor weighs 1 oz and is 3 inches in front of the CG, then it has a value os +3oz in. If the servos weigh 1/4oz and are mounted in the tail (4 inches behind the CG), then they will have a value of -1oz in. When you have all these values, you add them up. If you get to 0, then the plane will balance on the CG. If the result is positive, it will be nose heavy. The idea is to start with the CG point where you want it to be. Then move things around until you get a 0 result.

I hope that helps,
Joe

[dtknowles]

Thanks for the info., Tim. I don't understand the formula, however. What does the # sign stand for? Thanks, Dennis


Dennis the # indicates that the next thing is a subscript

d#mot = d subscript mot = distance from the reference to the balance point of the motor

W#mot = W subscript mot = weight of the motor

Tim

[Dmerino]

Thank you, Tim for clarifying that #. Dennis
Dennis the # indicates that the next thing is a subscript

d#mot = d subscript mot = distance from the reference to the balance point of the motor

W#mot = W subscript mot = weight of the motor

Tim