If you are trying to stay strictly within Part 103 guidelines, the plane itself, minus pilot and fuel have to be 254 lbs. or less (unless you have a parachute). If you add a pilot, and fuel, and a sleeping bag, those are considered cargo, which add to the loading on the wings. I do not believe there is an upper limit as far as a cargo is concerned for Part 103 airplanes. There is, however, a maximum stress limit of the Legal Eagle XL airplane as designed, which is 575 lbs. gross MTW. You, as pilot in command, can make the determination whether you will exceed the stress limits of the plane or not. The prototype was checked out, and if I’m not mistaken, was unofficially certified to be 4.4 G’s. Maybe Leonard can verify this.
In a nutshell, you are recommended not to exceed the gross MTW (maximum take-off weight) of 575 lbs. for the LE XL So, in answer to your question, “What is the useful load?”, the answer is 575 lbs. minus whatever you plane actually came in at for its final weight. Let’s say it is 254 lbs. Therefore, 575 - 254 = 321 lbs useful load.
