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).
Design calculations and specifications for the Seagull Dynamo.
| Identifier | WestWitteringFiles\J\November1922\ Scan118 | |
| Date | 20th November 1922 guessed | |
| -1- X.4010 - SEAGULL DYNAMO. Dynamo must, in hot condition, put up 13.6 volts on open circuit at a speed of 480 R.P.M. As a shunt machine it should do it at 440 R.P.M. (say). Hot armature resistance = .4 ohm (say) Max. field current say 4 amperes. Loss of volts = 1.6 Hence E.M.F. to be produced at 440 R.P.M. = 15.2 Assumed useful polar flux density = 5500 lines per cm² on minimum pole face. Armature circumference corresponding to five slot pitches = 5/20 x π x 3.625. = 1.965" = 50 mm. Length of pole face = 3.20 = 81.3 mm. This gives a useful flux per pole of 5500 x 5 x 8.13 = 223,500 Since E = (φ Z N p) / (60 x 10⁸ x b) Z = (60 x 10⁸ x b x E) / (223,500 x 440 x 4) = 463. No. of conductors decided upon = 464. No. of slots and coils 29. 8 turns per coil of 18 S.W.G. (.048"). Contd. | ||