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).
Test report on inductance and sparking performance with and without hedgehogging ends.
| Identifier | ExFiles\Box 45\4\ Scan112 | |
| Date | 6th December 1922 guessed | |
| -3- Contd. corresponding primary current for each case being noted. The tests were repeated with the hedgehogging at the ends sawn off. The results are given below:- Inductance. | | With Ends. | Without ends. | % Decrease. | |---------------|-------------|---------------|-------------| | Primary. | .00972 hys. | .00635 hys. | 34.7 | | Secondary. | 49.0 hys. | 54.5 hys. | 29.6 | Sparking Performance. | | Max. Gaps. | Primary Current. | | | Volts.| With ends. | Without ends. | With ends. | Without ends. | % Increase. | |-------|------------|---------------|------------|---------------|-------------| | 8 | 6.1 mm. | 6.2 mm. | .98 Amps. | 1.18 Amps. | 20.4 | | 12 | 7.4 mm. | 7.1 mm. | 1.44 Amps. | 1.57 Amps. | 9.0 | CAP. | ||