Correct answer is... 4.3 m/s It is equal to 850 ft/min. To give an example, Stinson 108 with it's climb speed of 4.3 m/s that takes off from airfield of elevation 100 metres (300 feets) will reach flight level 100 (10,000 feets or 3 km above mean sea level) after about 12 minutes.
Disclaimer: Our articles and data connected to climb speed of Stinson 108 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 climb speed from manufacturer of Stinson 108.