Lake Renegade Weight and Balance

On this page there is an example Weight and Balance graph which is an output from an Excel spreadsheet that I put together.
On the input form, one simply enters the appropriate weights at the standard stations.

Note: This example is for one particular plane.  Any or all of the numbers may be wrong. Do not attempt to use this chart for your plane.  It is provided as an example only.

Key to the Chart

The large (Blue/Black) lines are the standard CofG and weight limits.

The Red and Green small circles show the actual loading for a given situation.
(Green Circle = no fuel W&B)
(Red Circle = W&B with fuel)

The "mess" of smaller trapezoids show the total possible envelope of CofG for all fuel situations.  Once one figures out the lines, one can predict exactly how the W&B will change depending on how much fuel was loaded, and which tanks are emptied at which point in time.
A simple way to understand the "mess" of trapezoids is to ignore the inner lines, and just use the "bounding box" created by the lines.  All W&B possibilities are included.  If the "mess" is inside of the approved envelope, then you're done.

The lines at the bottom of the graph are "load lines."  Their slope is correct for weight at any standard station. They can be used to manually modify the graph as explained below.

How to Use the Graph

I have printed out a dozen versions of the graph that show the most common plane loadings as well as loads that are at various limits.  These I carry in the plane, and most of the time, this is all I need.
If I come across a situation that is not covered by the standard examples, that's where the "load lines" come into play.  As with the commercial "protractor template" one uses the load lines to modify a point on the graph.  For example: If another 50 lbs were added to the Mid Seat area in the example above, then one uses the Yellow load line.  50 lbs represents one vertical grid (see the weight axis).  One then draws a line "50 lbs long" at the slope of the yellow line, starting from the Red Circle.  This new point is the new W&B point.

Maybe a bit confusing at first, but one you do this a few times, W&B calculations are easy.

By the way - back to the "mess" of trapezoids.  The "width" of the trapezoids comes from the different possible seat positions.  If all seats are to the rear, then one would use the right side of the trapezoids.  If all seats are to the front, then use the left side.  If there is a combination of seat positions, then the W&B will fall somewhere inside the trapezoids.  In any case, one has a graphic picture of the possibilities.