Sir, Mr. J. L. Weatheritt's sorn.,% haillinformed and almost hysterica' Ws..k on Messrs. Rolls-Royce, and On y" remarks about the Napier _Sabre engin, . ontained in his letter under the heading \ ..oi:r versus Rolla-Royce" in the correspo-, ereT: columns

of your February issue aflor. c considerable amusement, even thou,... may not have been quite what the writQr intended.

The letter from Air Commodore. F. R. Banks, on the other hand, was most informative. It resolved thc problem of the admittedly small difference between the Posthumus and Setright figures for the power output of the Rolls-Royce "R" engine, and also confirmed my opinicyn that the figure of 2,640 b.h.p. for the mysterious "Merlin RM 17" said to have been given by Setright was far in excess of the optimum for any known Mark of Merlin running on any known fuel.

I was not previouAy aware that a Merlin variant circa 1945 had developed 2,000 b.h.p. on straight petrol, and more detailed information about this engine would certainly he of interest.

With regard to the Griffon, the original Mk. IIB gave 1,770 b.h.p,, the Mks. VI and 36 had this increased to 1,890 b.h.p and the Mks. 61-66, 85 and 88 developed 2,050 b.h.p.—all in standard production form and running on petrol of appropriate octane rating. The figure of 2,350 b.h.p. for the Griffon quoted by Air Commodore Banks might be applicable to one of the last named variants equipped with .a water/methanol charge cooling device permitting the use of higher boost pressures, or it may relate to some later Mark of the engine with which T am unfamiliar. The Air Commodore and I clearly hold opposite views as to the hypothetical suit ability of the Napier Sabre for use in ,n LSR attempt. I am 5611 inclined to regard any performance figures quoted in relation to the Sabre with feserve, although I agree that it was certainly a highly complex engine. In fact, I would go further and .suggest that

this complexity proved to be a source of weakness rather than of strength. G. P. LaT. SHEA-SIMONDS Figheldean This correspondence is now closed.—Ed.1