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).
Engineering calculations for armature and conductor dimensions, including space efficiency and pitch of teeth.
| Identifier | WestWitteringFiles\T\November1928\ Scan059 | |
| Date | 27th November 1928 guessed | |
| -4- Contd. Whence a = .00815 / 1.00 = .00815 sq.ins. Allowing 37% space efficiency in slots, slot area = 2 x .00815 / .37 = .0044 sq.ins (say) Take slot depth = .390" Then slot width = .112" Width of slot for insulation == .050" Therefore width of conductor = .062" Depth of slot for insulation = .090" Hence depth of conductor = .150" Space efficiency for conductors with unrounded corners = 2 x .150 x .062 / .390 x .112 = 42.5% C.S. area of conductor = .150 x .062 = .0093 sq.inch which, allowing for semi-circular rounding off, becomes .0085 sq.inch. Armature dia. = 3.050" Pitch of teeth at circumference = 3.050 x π / 37 = .259" Width of tooth at top = .147" Bottom of tooth is at 3.050 - 2 x .375 i.e. at 2.300" dia. Pitch at this diameter = 2.300 x π / 37 = .195" Width of tooth at root = .083" * * * one tenth of the way up = .083 + 1/10 of .064 = .089" (*Here see table p4a) | ||