Correct answer is... 14 m. It is equal to 47 ft. Wingpan is calculated as stright line from one wingtip to another, so shape of the wing is not taken as factor during measurement. The biggest civil aircraft is 88 m (290 ft) wide, so Beechcraft Model 18 has 16% percent of it's length. Typical jet airliners are about 34 m wide, so in the comparision Beechcraft Model 18 has 17% of aircrafts like B737 or A320.
Disclaimer: Our articles and data connected to wingspan of Beechcraft Model 18 are based on public data from various sources. We are very picky to select an reliable data providers, but we cannot guarantee that everything is 100% error-proof. We recommend for any serious purpose - as a rule of thumb - to request offical data about wingspan from manufacturer of Beechcraft Model 18.