Weight & Balance

The following weight estimates are preliminary. At this point their primary value is to facilitate preliminary CG calculations.

These numbers assume the use of the proposed 150 hp Hirth F40 engines (no longer being considered) and high-performance materials. Current estimates (2006) call for a slightly heavier aircraft.

Zero longitudinal datum is taken at the duct leading edge. Negative station values are forward of the datum, positive values aft.

A 170 lb pilot with full sump tanks will put the flying weight at 1097 lb and the CG at FS -2.55—approximately correct for the present planform.

(Note: A comprehensive CFD analysis will be required to pin down the optimal CG location.)

The aircraft’s light weight, combined with the forward location of the pilot seat, makes the aircraft sensitive to pilot weight. Nose ballast will be necessary for light pilots, and possibly tail ballast for heavy ones. For more permanent CG adjustments the batteries can be moved aft from their present locations in the nose.

These numbers will undoubtedly change as detail design proceeds. The intention here is to illustrate that the light engines and self-bracing structure provide an opportunity for a very light airplane, and that CG concerns have been addressed.