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).
Report page detailing conclusions from tests on magneto ignition systems, specifically the effect of a 'third point'.
| Identifier | ExFiles\Box 63\4\ scan0026 | |
| Date | 26th May 1918 guessed | |
| .. (2) found the effect to be the same when high tension condenser was connected, in spite of the radical alteration in the type of spark. On the other hand we have had very definite results of the opposite (negative) kind; we have actually observed the bringing up of the third point to completely stop, otherwise regular firing. This has happened with the small motor cycle type magnetos, both Bosch and Dixie but not with the Bosch Z.R.6 And we have had numerous cases where no decided effect is apparent. The conclusion arrived at are, in the main as follows:- The effect of the third point :- (1) Is not altered by varying speed of magneto. (2) It not altered by advancing and retarding. (3) is not altered by addition of high tension condenser. Provided in each case (1) (2) (3) spark gap length is altered to suit (4) Is not appreciably affected by polarity (5) Depends upon type of magneto. (6) Depends most of all on actual shapes of spark points and on shapes and positions of insulated and uninsulated conductors in immediate neighbourhood of gap. To bear (5)&(6) out we record the following. We had two ordinary test gaps X and Y in different positions. On X the effect was positive with the Bosch Z.R.6 and Bosch Z.A.2 and on Y the effect was negative with the Bosch Z.A.2 and the Dixie but positive with the Bosch Z.R.6. In the Contd. | ||