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 the electrical properties and core sections of Bosch FU6R and Watford EG6 magneto armatures.
| Identifier | ExFiles\Box 65\3\ scan0310 | |
| Date | 20th August 1928 | |
| EFC. WD.{Mr Wood/Mr Whitehead}5. 20.8.28. R.{Sir Henry Royce} BOSCH FU6R AND WATFORD EG6 MAGNETO ARMATURE COMPARISONS. We have now been able to obtain comparative figures of these two armatures, and also winding and core particulars of the Bosch, which has been unwound. The electrical quantities of the winding were measured and are set out for convenience in the following table :- Watford EG6 Armature. Primary resistance:- .41 ohms at 20°C. Primary impedance:- 1.68 ohms Primary inductance:- .0051 henry Secondary resistance:- 3280 ohms at 20°C. Secondary impedance (50~): 6010 ohms. Secondary inductance:- 15.8 henries R.{Sir Henry Royce} Bosch FU6R Armature. Primary resistance:- .70 ohms at 20°C. Primary impedance (50~) :- 4.00 ohms. Primary inductance:- .0124 henry. Secondary resistance:- 10140 ohms at 20°C Secondary impedance:- 13050 ohms. Secondary inductance:- 25.4 henries. It will be seen from these figures that the values of resistance and inductance of the Bosch are considerably greater than those of the Watford. The Bosch armature is longer than the Watford and the iron section of the core as compared with an EG6 core (which we believe is much the same as the HMG) is larger. The core sections are approximately :- Bosch. Watford. | ||