The design of the Do 31 was heavily reliant upon its engine configuration. Dornier had opted to incorporate the British-built Bristol PegasusBy the time of the first flight, Rolls-Royce had taken over Bristol Engines. vectored-thrust turbofan engine, an existing powerplant that was most famously used to power the Harrier jump jet. On the Do 31, a pair of Pegasus engines were housed in each of the two inboard nacelles; during the vertical phase of flight, additional lift was provided by an arrangement of four vertically mounted Rolls-Royce RB162 lift engines located in each of the outer nacelles.Dow 2009, pp. 233-234.
