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).
Power loss on the Spectre exhaust system.
| Identifier | ExFiles\Box 93\1\ scan0008 | |
| Date | 5th December 1934 | |
| To E.{Mr Elliott - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Swdl{Len H. Swindell}; c. to Da.{Bernard Day - Chassis Design} Hs{Lord Ernest Hives - Chair}/Swdl.{Len H. Swindell}3/KW.5.12.34. Power Loss on SpectreCodename for Phantom III Exhaust System. Power losses with the exhaust system Hs.{Lord Ernest Hives - Chair}1526 have been taken on No. 2 unit which has Aerolite pistons and Hs.{Lord Ernest Hives - Chair}1536 camshaft. The maximum power developed on this unit with the open exhaust is 199.4 B.H.P. at 3750 r.p.m., and it is at this speed that the following losses are taken, the curves being shewn on S.P.3. Curve 2 is with manifolds, downtake pipes, front expansion box and intermediate pipe, the power loss being 15 B.H.P. giving 2 ins.Hg. back pressure in the manifold. From previous tests this can be taken as 8 B.H.P. in the manifolds and 7 B.H.P. for the remainder. Curve 3 is by fitting the silencer, without the 2 "top hats", main centre tube and swan neck, the only restrictions in the silencer being the inlet cone and the swan neck adaptor. This condition accounts for a further 11 B.H.P., the total loss now being 26 B.H.P. and giving a back pressure of 7 ins.Hg. Curve 4 is by fitting the swan neck, otherwise the conditions are as Curve 3, thus giving a further loss of 10 B.H.P. with a total of 36 B.H.P. and a back pressure of 13 ins.Hg. Curve 5 is the complete system, having fitted the "top hats" and the main centre tube, giving an increased loss of 18 B.H.P., the complete silencer loss being 54 B.H.P. or 27% of the maximum power, and creating a back pressure of 21 ins.Hg. This is almost identical with the results obtained on the original SpectreCodename for Phantom III silencer, which had a standard Ph.II silencer which registered a back pressure of 20 ins.Hg. Hs{Lord Ernest Hives - Chair}/L.H.Swindall. | ||