The Weight Shift Formula
The weight shift formula can be very useful and save you from re-calculating the weight and balance of your airplane if your C of G is out of limits.
There are four components to the weight shift formula; weight to be shifted, total airplane weight, change in C of G, and distance the weight will be moved.
The total weight of the airplane is 2450. Our C of G is too far aft and we need to move some weight around to bring it back into limits. We know we have 100 pound bag in the aft baggage compartment. If we move that forward to the rear seats will our C of G be in acceptable limits? We will be moving the bag from station 123 to 73 (50 inches/stations)
100 * 50 = 5000
5000 / 2450 = 2.04
X = 2.04
Always cross multiply the weight and the distance moved and then divide by the total weight and you will end up with X. In this case moving the 100 lbs bag forward 50 stations would not put us within acceptable limits. Our new C of G would be at 93.96 which is still .96 inches too far aft of the C of G envelope.
If we removed the bag completely would be be within limits? We can use the WEIGHT CHANGE FORMULA to find out without redoing the W & B.