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).
Condenser capacity and its effect on ignition system performance, comparing mica and paper condensers.
| Identifier | ExFiles\Box 54\5\ Scan174 | |
| Date | 29th December 1921 | |
| contd:- -4- EFC {E. Fowler Clarke - Electrical Engineer} 2/LG29.12.21. be careful to meet these conditions as far as possible, in fact, to affect the most satisfactory compromise. For instance, at 1500 distributor speed or 3000 R.P.M. engine speed, our present standard capacity (.21m.f.) will allow of a regular firing gap of 6 mm. With the proposed increase of 50% condenser capacity, this, at that speed, is reduced to 4.5 mm. though in the first case the capacity is amply sufficient for quenching the primary spark. We are, however, preparing a 40/50 H.P. condenser of this increased capacity both with mica and with paper. We have an idea that the damage to primary ignition points may be done at the instant of make rather than that of break. You may remember that we have already proved the existence of a spark at make by synchronously eclipsing the contacts at the instant of break and noting the result. There may be still some oscillation going on in the primary when the contacts again make at which instant, in this case, there may be an extremely high frequency oscillatory discharge of the condenser across the points. This point we are again investigating on the Goshawk ignition. We think that such a tremendously sudden liberation of energy of the contacts may have a bigger disintegration effect than that of a more conductive discharge at break. One would think that a paper condenser with more dielectric hysteresis would be less harmful in this respect than one of mica. EFC. {E. Fowler Clarke - Electrical Engineer} | ||