Weight/Balance chart

[Tomas J]

I'm working on the weight/balance and try to make a spreadsheet for the calculation. I have been looking at charts from other airplane, and there is one thing I'm wondering about. They can have a cut corner, like this from a PA-28. Why is that corner cut? What I can understand when I try do modified the chart for my RV-4, is that it shall not have this cut corner. Am I right?
If anyone have a spreadsheet for me I would be very grateful...

[islandmonkey]

The blue line delineates an envelope within which flight is permitted at that particular loading. The corner cut is there because flight is not allowed outside the envelope at approx 880 212cm or at approx 1050 220cm. These two point are joined to form the cut. In other words you are not allowed to fly at max weight 1050 at 212 but you can fly at 880 at 212.

You will not need a corner cut for your RV-4.

[Tomas J]

Okay, so aircraft with such a curve has a different front center of gravity limits at different mass. And something like this does not apply to RV-4 ... then I have obviously got it right.
Thanks Anthony