Those are the hard facts and choices of production, the 301 Peregrine engines produced probably cost Rolls Royce 600-900 in lost Merlin production, so the RAF got two squadrons of Whirlwinds, lost the engines for at least 600 S/E fighters and Rolls Royce lost money on the whole thing. It is very difficult to rationalise production when you are making more than one product."To produce further Whirlwinds even of the current type will necessitate a curtailment of some other Rolls Royce programme" and that more Peregrines could only be produced at Rolls-Royce's Derby factory "with more than a 2 to 1 reduction of Merlin, or by postponing the Griffon'.
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