Originally Posted by
100LL
Ok I have been looking into this question for quite some time and still can't figgure out an answer. What I'm looking at is to find a way to compute how much weight must be added at lets say station A, to move the CG so many inches forward or aft. All the weight shift forumulas I have found don't work with my scenario so is there another way to figgure this out?
So in other words, for example the airplane has exceeded the forward CG envelope, so I'm trying to figure out how much ballast must be added to the baggage compartment to bring my CG so many inches aft. Would be nice to know there is a simple computation I could do without the hassle of making numerous W&B calculations over and over again.
There is, these W & B formulas found in aviation textbooks. They can also be derived easily using basic calculus, which is a good way to prove to yourself they work. (Note: to get these to line up correctly I had to insert periods as spacers.)
a)
weight to be added or removed = ......
change in CG
old total weight .................... distance from weight to new CG
b)
weight to be shifted =......
change in CG
old total weight ............. distance weight is shifted
Ex. CG needs to move 1 inch aft to be within limit. Say it's 45 inches from the baggage compartment to the new/desired CG location, and say the airplane weighs 5,000 lbs. Using formula (a)
x ... = ...
1
5000 ... 45
Solve for x: 111 lbs. needs to be added to the baggage compartment.
Use formula (b) when you would rather shift some weight than add or remove it.
Hope this helps.