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).
Urgent experiment to determine the magnetic flux of a self-starter carcass for aero engines.
| Identifier | ExFiles\Box 34\3\ Scan091 | |
| Date | 24th March 1915 | |
| R R.{Sir Henry Royce} 320 A (400 T) (S C. 536. 15-2-15) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 1546. COPY. X.2642. URGENT EXPERIMENT. First To Oy. from R.{Sir Henry Royce} c. to J.{Mr Johnson W.M.} c. to Ns.{Norman Scott} c. to E.{Mr Elliott - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} for Mr. Ellis. R1/IB2431B. March 24th 1915. Re - Self Starter for Aero Engines. You have one or two carcasses of the starter motor, and I am anxious to know the magnetic flux that this carcass is capable of passing through the armature core; it was designed for a flux φ = 156,000 lines through the armature. To find this, I want you to take one of the armatures, preferably the one with three coils per slot (total 102 armature conductors, wave wound) and wood wedges, and run it at 3000 revolutions in the carcass driven by an electro motor. Its own standard brushes should be fitted into the brush holders. The field coil should be wound with a suitable wire for separately exciting, according to the voltage that you have at your disposal, so that you can get 1000 A.T. per pole. The exciting current should be started at about half the normal value in A.T. (when normally excited the armature should give about 16.5 volts.) and increased by about 10% at a time, until it gives about 1.5 times the normal excitation (which we believe is 640 A.T. per pole). If we then take the exact speed, the number of wires on the armature, and the electro motive force given at the brushes )I want you to carefully note this for each excitation), we shall be able to get out the magnetic flux passing through the armature for each excitation. This | ||