There was a realisation too, that mild steel, familiar from bicycle manufacture but with a low strength-to-weight ratio, was not going to be the material of choice once the problems of joining aluminium alloy members together and preventing their corrosion had been solved.

Vickers in the UK were one of the first to make steel-framed and sparred aircraft that flew, with their series of R.E.P-type monoplanes no.s 1-8 produced between 1911 and 1913.

Barnwell borrowed from marine experience by using duralumin sheet, varnished to prevent corrosion and used these to make the fuselage in four sections.

The two forward sections were semi-monocoque (i.e. open channels) with braced longitudinal upper members which, bolted together, held the engine, a water-cooled inline upright 140 hp (100 kW) Hispano-Suiza) and the pilot's cockpit.

The second M.R.1 did not fly until late in 1918 when the metal wings were at last ready, powered by a 180 hp (130 kW) Wolseley Viper engine.