How It Works

SeeGee™ Center of Gravity Calculators are simple mechanical devices that assist in computing center of gravity of aircraft to satisfy safety and regulatory requirements. It uses no batteries or programming, but operates as a circular (polar coordinate) slide rule. The templates that are displayed on this website are laminated to a rigid condition, and then two cursors are mounted on the face of the calculator. These are manipulated to perform the functions described below.

These devices work by mechanically summing up the moments of the load on the aircraft and displaying the results on the lower half of the calculator in a moment vs. weight envelope (index is moment). The empty (or operating) weight and moment are used with a simple formula (specific to each aircraft type) to find the “starting point” of the loading operation. This Operating Index (unique to each individual aircraft), in conjunction with the associated weight will display in the lower, envelope portion of the calculator. Then the position in the envelope can be continuously monitored as the load in each area of the aircraft is added using the scales in the top half of the calculator. The calculators provide an intuitive view of the effect of adding fuel or payload to the aircraft, and when payload needs to be moved or adjusted due to exceeding limits, the amount of weight to be moved is also easy to determine.

SeeGee™ Center of Gravity Calculators are very accurate and will provide results that can be comparable to long hand, electronic calculator computations. But the advantage is that the SeeGee™ calculator is much faster and will not require manipulating columns of large numbers, which tend to be prone to error.