Weight and Balance Formula, Can one calculate the envelope

wrote in message
om...
You will need a bunch of "if-then" statements to define the acceptable
envelope(s). Look it up on Excel Help. Lotsa luck though as the same
guys must write the help as write the original software package.


I have an Excel worksheet with NO if-then statements anywhere.
I used the data from the pilot's handbook to determine the corners
of a graph that represents the W&B envelope. Then I built a table
duplicating the W&B factors from the handbook along with the calcs for the
moment arms. Down at the bottom where the weights and moment arms are
totaled, I transfer them to the graph using an asterisk symbol to represent
the single data point.
Would you please give me an example of a couple if-thens you used,
please?

Excel uses only an IF statement. I have used it in an unrelated large
scale water flow situation, but found it messy to use. I was thinking
that a series of them could be used to end up with a yes (OK) or no
answer, but I like your concept better of showing where you are on the
actual CG/GW range.

In addition you could show the effect of burning off fuel as a line.
I don't think any 172s will present a problem in this area, but some
others like Bonanzas can.

My experience is that it is hard to exceed the CG range of a 172, but
easy to exceed the gross weight.

wrote in message
om...
Excel uses only an IF statement. I have used it in an unrelated large
scale water flow situation, but found it messy to use.

Most likely because you are not sufficiently familiar with Excel. The fact
that you think that "Excel uses only an IF statement" supports this
likelihood. It has hundreds of worksheet functions, not counting all of the
add-ins that provide even more functionality.

I don't know what calculations are involved in a "large scale water flow
situation", but I doubt it really required exclusive use of nested IF
statements.

[...]
In addition you could show the effect of burning off fuel as a line.
I don't think any 172s will present a problem in this area, but some
others like Bonanzas can.

You could draw a line, but why bother? All you really need are the two
end-points. I've never seen a W&B graph that had a convex curve, which
would be required to allow the takeoff and landing weights to fall inside
the envelope, while still having an intermediate state outside the envelope.

Pete