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).
Comparison of specifications for Rotax A.T.13. and U.S.A. Bosch dynamos.
| Identifier | WestWitteringFiles\F\March1921\ Scan45 | |
| Date | 17th March 1921 | |
| 17. 3. 21. DYNAMO PARTICULARS. Rotax A.T.13. U.S.A. Bosch. Weight. 27 lbs. 21 lbs. Weight of armature. 11.5 lbs. 7.2 lbs. Air gap (radial). .020" .020" Field coil resistance (cold). 1.8 ohms. 3.5 ohms. Number of slots. 14 17 Coils per slot. 2 2 Armature resistance (cold) .42 ohms. .42 ohm. Span of field winding in electrical degrees. 110º 110 Speed to attain 13.6 volts normally hot. 420 600 (struck through) Max. output normally hot (amps) 8.2 7.7 Corresponding speed 840 1300 Final max. output fully opt to 14 volts (amperes) [handwritten: battery] 8.4 7.5 Temperature rise by thermometer (ºC). 65.5 33.5 " " " field coil resistance (ºC). 87.5 57.3 (upside down text at bottom) R.R. 238A (100 (T) (S.H 798. 10-12-20) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2947 | ||