Blackburn B20 | BAE Systems | United Kingdom The unique Blackburn B20, which was built at Blackburn Aircraft works at Dumbarton, was a twin-engine reconnaissance aircraft designed to meet Specification R.1/36. It was based upon a patented design study (UK Patent No 433925) by Blackburn's Chief Seaplane Designer Major John Rennie. Three died in prototype crash Three died in prototype crash
