One way to get a handel on your airplanes as to their endurance is done by using a geared hand pump not an electric. Just count the cranks filling an empty tank and at the end of each flight defuel what is left counting cranks before refueling and you soon will have a good handlel on how long you can fly.

Do find a experianced mentor to get you started flying rather than going it alone. Going at it alone usually results in disaster no matter what airplane.

John