Mitchell intended to submit a monoplane but developed a conventional biplane alongside it as a backup and reference design. Both used the Rolls-Royce Goshawk, then called the Kestrel S, with evaporative cooling intended to reduce weight and drag. Joint work on Schneider Trophy racers had given Mitchell confidence in Rolls-Royce's experimental department. Surviving layout drawings dated February 1931 followed preliminary wind-tunnel work and preceded the formal F.7/30 specification, while the Air Ministry had already signalled its engine preference. The biplane incorporated wing condensers, four proposed Vickers guns, bomb racks, and measures to improve the pilot's view. Its thin lower wings raised doubts about fitting their guns without substantial blisters or fairings. Because the monoplane remained the principal design, the biplane may have served mainly as a benchmark.
Chapter · 2:53:37-2:59:19
Mitchell's biplane benchmark and the road to the F.7/30 fighter
R. J. Mitchell developed biplane and monoplane studies in parallel, using Rolls-Royce evaporative cooling and early wind-tunnel work before the F.7/30 requirement formally appeared.