The A-20 Havoc met many Army requirements, but planners worried that it lacked the firepower needed for war against Germany or Japan. A proposed 75 mm nose cannon would have upset the balance of its narrow single-pilot fuselage, while the wider B-25 could accommodate such a weapon more easily. Heinemann instead asked for the desired performance figures and sketched a comparison with the A-20 on the back of an envelope. Douglas approved work on a faster, more powerful aircraft with heavier armament and a wider fuselage. Within weeks the team produced three-view drawings of the future A-26 Invader, with side-by-side forward seating and a third crew position. The episode is a compact example of requirements analysis turning an unsuitable modification into a clean-sheet design.
Notable Point · 3:32:17-3:35:44
How an armament problem became the A-26 Invader
Ed Heinemann's account turns an Army request for heavier firepower into a rapid requirements exercise and the outline of a new attack bomber.