From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Visit to Farnborough comparing performance figures for the F.XII.B and Lion X.A engines, and discussing related development issues.
| Identifier | ExFiles\Box 36\2\ scan 200 | |
| Date | 14th May 1929 | |
| X 2934 To A.F. from F.{Mr Friese} c. to E.W.H., Or., Hs.{Lord Ernest Hives - Chair} & A.{Mr Adams} F.4/AV/14.5.29. Dictated 2.5.29. IIIF Performance Figures. I visited Farnborough yesterday regarding the above and obtained the following figures:- F.XII.B Lion X.A 535 HP at 2250 RPM. 553 HP at 2360 RPM. 570 HP at 2500 R.P.M. 583 HP at 2585 RPM. Ft. Top Speed Time R/c. Top Speed Time R/c. 2000 140 2 950 152 1.4 1375 5000 148 5 1/4 1050 150 3.75 1160 10000 141.5 11 1/4 825 144.5 8.9 810 15000 131.5 19 3/4 475 137 17.0 460 20000 ? ? 125 117.5 47.0 110 Up to 5,000 our engine is definitely inferior to the Lion due to the use of gate throttle with the h.c. engine. Above 5,000 there is very little in it and what there is is probably largely accounted for by propellor differences. The Lion F.X.A was the forerunner of the Lion XI. The Lion XI has now been established at 20 HP less than the Lion X.A so that the figures will not be quite so good for the Service Lion III.F as shown above. The above figures are the result of one set of tests. These will be repeated twice and the average of the three results taken. These should be ready towards the end of next week and will form official figures. Capt. Penn is pushing ahead on both the high and low compression engines and giving the matter first priority. He is having a huge lot of trouble with water boiling on the low compression III.F due apparently to the telescopic tubes on the retractable radiator being out of round so that the glands leak when the radiator is out allowing the pump to draw air. at any rate the symptoms are that the engine boils worse as the radiator is let down into the slipstream. Capt. Penn thinks he will require new telescopic tubes, which looks like a source of delay which will have to be watched. F.{Mr Friese} | ||