Legend Cub weight & balance calculation

The following figures are for N757LC as modified after a nose-over accident in which a solo pilot applied the brakes too hard when taxiing. (Nearly a third of all Legend Cubs have been stood on the nose.)
  • Max weight ... 1,320.0 lb
  • Empty weight ... 861.0 lb with 5 quarts oil and 2 gallons gasoline
  • Useful weight ... 459.0 lb (with 20 gallons of gas, that leaves 339 lb for pilot, passenger, and gear)

Datum: leading edge of wing

  • Allowable c.g. range @ 1,320 lb gross weight: 12.5" to 21"
  • Allowable c.g. range @ 1,120 lb gross weight: 11.5" to 21"

Replacing the metal prop with a composite version took 14 pounds off the nose, and switching to a more robust tailwheel added 3 pounds to the other end. All of which moved the center of gravity of the empty plane back to 13.7" (from 11.6" when Seven Lima Charlie was delivered.) In addition, a solo renter is required to carry a 25-pound pack in the baggage compartment. For my purposes, fully kitted out at 180 lb, a full load of gas, and the mandatory weight in the baggage compartment, Seven Lima Charlie weighs 1,186 lb and our c.g. is 15.08" aft of datum--much better than before:

757LCWeight Arm Moment
Aircraft (with 5 qt oil, 2 gal gas) 861 lb 13.7" 11,796
Fuel: 20 gallons 120 lb 24" 2,880
Pilot, front seat 180 lb 11" 1,980
Passenger, back seat - 36" -
Baggage compartment 25 lb49" 1,225
Total 1186 lb15.08" 17,881

Source: Weight & balance sheet in N57LC aft cockpit, as amended; email from Darin Hart, American Legend Aviation