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).
The development status of Goshawk engine ignition system components, including coils, condensers, and cams.
| Identifier | ExFiles\Box 54\5\ Scan182 | |
| Date | 1st February 1922 | |
| X. 3485. To Ry. from EFC. {E. Fowler Clarke - Electrical Engineer} c. Ey/WER. c. EP. {G. Eric Platford - Chief Quality Engineer} c. Hy. {Tom Haldenby - Plant Engineer} c. WOr. {Arthur Wormald - General Works Manager} EFC {E. Fowler Clarke - Electrical Engineer} 1/T1.2.22. X.3485 - GOSHAWK IGNITION. With reference to the various items on the Goshawk ignition, the position as regards this department is as follows :- Coils. It is now definitely decided that the B type of coil will be used as standard. Ballast Resistance. The value of the ballast resistance as already arranged by Lec. is almost certainly right in magnitude to work with the B coil. We have only to finally confirm this and it is considered unlikely that any change will be required. Condenser. We have experiments in progress in the making up of roll condensers, so that the most approved construction is not yet settled. Experiments are also in progress with a view to deciding suitable capacity limits for these. Cam. We are looking to the D.O. to slightly alter the cam if necessary so that a maximum platinum point gap of .020 is obtained, corresponding to a make ratio of the contact breaker of .500. We would also like to point out that a comparison of the cams of our experimental sets with those of the Bosch ignition sets shows the grinding of these latter cams to result in a somewhat smoother surface, and we consider that this has a good deal to do with our premature wear of the continental bakelite rubbing block which has been experienced so far on the experimental sets. We think attention should be given to this point. If, to obtain the .020 lift, it only requires a slight modification to the cam, it would appear legitimate to alter slightly the shape of the rubbing block to secure this, as on the American ignitions the shape of this block is more rounded, and yet appears to give satisfactory service, at any rate on a cam of sufficient smoothness. Spring Pressure. The desirable amount of spring pressure between the contact points (closed) will shortly be fixed. The contact points to be standardised are 25% iridio-platinum welded to steel studs, as samples recently supplied to us from Messrs. Reynolds. Contd. | ||