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).
Calculation table for the ampere-turns required to produce a specific magnetic flux in an electrical machine.
| Identifier | ExFiles\Box 51\1\ Scan019 | |
| Date | 6th July 1921 guessed | |
| AMPERE TURNS NECESSARY TO PRODUCE FLUX REQUIRED. | Part | Matl. | Length. | Virtual Section (sq.ins) | Total flux. | Flux density inch units. | Flux density Cm. units. | H.{Arthur M. Hanbury - Head Complaints} | A.T. per inch. | A.T. | |---|---|---|---|---|---|---|---|---|---| | Armature teeth. | Lamin: iron. | .53 | 5 x .100x2.75 = 1.375 | 170000 | 123600 | 19150 | 272 | 550 | 292 | | Armature core. | " " | .65 | 2 x .50x2.75 = 2.75 | 170000 | 61800 | 9580 | 5 | 10 | 6 | | Air gap. | Air | .015 | 2.01 x 2.75 = 5.53 | 170000 | 30700 | 4760 | 4760 | 9620 | 144 | | Pole core | Lamin: iron. | .70 | .95 x 2.75 = 2.61 | 204000 | 78200 | 12120 | 9 | 18 | 13 | | Yoke. | M.S. | 1.80 | 2x.275x4.5 = 2.47 | 204000 | 82600 | 12800 | 12 | 24 | 43 | | | | | | | | | | Total | 498 | | ||