Correct answer is... 0 . It is equal to 0 lbs. Empty weight of Supermarine S.5 is total weight of the airframe, engine, avionics and all other systems installed by manufacturer. It is lower weight then empty speed of other aircrafts of a similar size. Average is about 313 kg (691 lbs).
Disclaimer: Our articles and data connected to empty weight of Supermarine S.5 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 empty weight from manufacturer of Supermarine S.5.