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).
Table of lowest speeds in R.P.M. for various magnetos during regular firing on 5.5mm air gaps.
Identifier | WestWitteringFiles\F\March1921\ Scan60 | |
Date | 22th March 1921 | |
Handwritten: X 2375, X 4181, X 39/6 Typed: X.430. MAGNETOS. TABLE OF LOWEST SPEEDS IN R.P.M. FOR REGULAR FIRING ON 5.5mm. GAPS IN AIR. N.B. Test range between advance and retard 34º in all cases (except Watford E.O.6a. = 32º). TABLE DATA: Column Headers: Magneto., Type & No., X. No., Lowest speeds. (Adv., Cent., Retd.), Remarks. Row 1: Magneto: Watford. Type & No.: E.6, 45638. X. No.: 2375 Lowest speeds - Adv: 150, Cent: 250, Retd: 340 Remarks: Advanced position same as maker's. (Gaps had to be reduced to 4.5 mm. in fixing range by high speed sparking). Retarded position 4º later than maker's. Row 2: Magneto: Watford Type & No.: E.6, 45168 X. No.: 2375 Lowest speeds - Adv: 156, Cent: 226, Retd: 320. Remarks: Advanced position 3º earlier than maker's. (Gaps had to be reduced to 4.5 mm. in fixing range by high speed sparking). Retarded position 1º later than maker's. Row 3: Magneto: Watford. Type & No.: E.O.6a, 46993. X. No.: 4181a. Lowest speeds - Adv: 160, Cent: 140, Retd: 136 Remarks: Increased advance or retard on maker's range unobtainable. Hence working range 32º as maker's. Row 4: Magneto: Watford. Type & No.: E.O.6b, 48919. X. No.: 4181b. Lowest speeds - Adv: 170, Cent: 155 (Weighted average of two sets of figures), Retd: 150. Remarks: Retarded position same as maker's, this setting chosen owing to slower speed for regular sparking obtained on retard. Advanced position 29º later than maker's. Contd. Footer Text: R R.{Sir Henry Royce} 285A (OD) (I.S.H. 986. 19-3-21) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 3018 | ||