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).
Specification details for special coils designated G.II, covering coils No. 1, 2, and 3.
| Identifier | ExFiles\Box 45\4\ Scan103 | |
| Date | 25th November 1922 | |
| TU079 b Hs.{Lord Ernest Hives - Chair} - from E.J.B. EJB.1/LMG.25.11.22. Wcr. BY.{R.W. Bailey - Chief Engineer} BPO. Special Coil for G.II. Coils No. I & 2. These coils are made up as follows,- Material - Mouldinsite. Case - .500" deeper and .062 larger in bore. H.T.Terminal has been vulcanized with hard rubber .032 thick. Primary Winding - .500" longer. 300 turns of .032" dia. D.S.C. Wire in 4 layers, each layer covered with 2 turns of plain paper and painted with E.L.O. Varnish. It is intended to use silk instead of paper in future as paper has a tendency to crack when being covered with wire; also, silk is more absorbent and holds the varnish better. Secondary Winding - 18,000 turns of .004" enamelled wire in 48 layers, each layer insulated with 2 turns of .001 oiled paper. This gives .250" extra clearance at each end. The distance from the top layer of secondary winding to the inside of case is approx: .187 and this extra space is accounted for by having 4 layers of primary instead of 6 as on the standard coil; and also to increasing the bore of case. We have put a sleeve of rubber tubing over the H.T.Wire where it comes through the case to the H.T.Terminal. Coil No.3. This is exactly the same as Nos.1 & 2, excepting that we have spread out the secondary winding and HAVE wound the 18,000 turns in 38 layers. This gives us a space of .312" between the secondary winding and the bore of the case. Mr.Archer has this coil on Test. E.J.B. | ||