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).
Testing the Spectre Exhaust System, detailing efforts to reduce 'tinniness' using rope lagging.
| Identifier | ExFiles\Box 93\1\ scan0017 | |
| Date | 24th April 1935 | |
| X323 To E.{Mr Elliott - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Wym.{G. Harold Whyman - Experimental Manager}3/KW.24.4.35. SpectreCodename for Phantom III Exhaust System. Further to our report Hs{Lord Ernest Hives - Chair}/Wym.{G. Harold Whyman - Experimental Manager}28/KW.29.1.35, we have now tested the above system with the larger front expansion chamber, and the oval shaped swan neck pipe. The larger expansion chamber has given us a distinct improvement both in booms and tail pipe noise, the only boom apparent in the system now is at 30 m.p.h. light throttle. The tail pipe noise we consider passable with original swan neck pipe fitted, the oval shaped pipe being far too noisy. Our greatest trouble at the moment is the terrific amount of "tinniness" prevalent throughout the whole system, with the downtake pipes and the front expansion chamber as the worst offenders. We have, during the short time that 30-EX has been available for exhaust system work, experimented with 5/16" dia. rope lagging to try and overcome this trouble, but we have not met with the success we had hoped for. The following gives in detail the amount of rope lagging applied, and where :- (a) Both manifolds lagged with one thickness of 5/16" dia. rope. (b) Both downtake pipes lagged with 2 thicknesses of 5/16" dia. rope. (c) Front expansion box lagged with 2 thicknesses of 5/16" dia. rope. (d) 2 copper and asbestos washers fitted between joints of expansion box and downtake pipes. (These washers are essential for a gas tight joint). (e) Intermediate pipe lagged with one thickness of 5/16" dia. rope. (f) Front 3 ft. of rear silencer lagged with one thickness of 5/16" dia. rope. | ||