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