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).
Solutions for improving the cooling and reliability of aero engine sparking plugs.
| Identifier | ExFiles\Box 58\2\ Scan174 | |
| Date | 26th January 1935 | |
| V18/2. To Hs.{Lord Ernest Hives - Chair} from E.{Mr Elliott - Chief Engineer} E.1/HP.26.1.35. c. Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} By.{R.W. Bailey - Chief Engineer} E/Rbr.{Mr Rubbra} Hs{Lord Ernest Hives - Chair}/Wd.{Mr Wood/Mr Whitehead} Hs{Lord Ernest Hives - Chair}/Wst: E/PSN. *as we did on the Schneider Cup engines. re Aero Sparking Plugs. We are informed by Hs{Lord Ernest Hives - Chair}/Wst. that he is having difficulty in obtaining plugs which will stand up to the higher rating conditions on the P.V.12. pancake head, and he believes that the plug makers are just about on the limit of what they can do in producing cooler running plugs. It is also understood that conditions are somewhat the same on the Kestrel Ramp head. The liquid cooling of the plug bosses is up to quite a high standard on the Ramp head and better than we are used to on our present production engines. We do not think this can be further improved. There remains the possibility of withdrawing the plugs slightly away from the combustion space to shield them from the flow of heat, and also to dispense with the use of inserts and screw the plug direct into the aluminium to further improve the cooling.* The former move can be tried out by modifying the inserts, and we will issue some suitable alternative inserts accordingly for both Kestrel Ramp head and Merlin. These can also be tried on the Single Cylinder units for detonation effects etc. With regard to screwing the plug direct in the aluminium, I personally think we ought to find out how much we are likely to get out of this. We will arrange for the alternative Merlin "C" cylinder head to have this feature with smaller plug bosses to still further improve the liquid cooling. We also propose to arrange if you are in agreement that one or two of the Merlin "C" heads to the design issued should be tapped with the plug threads for trial, they can always be converted to carry inserts. We should also like somebody to find out if | ||