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).
Comparison of dynamo machines, specifically the Bosch, Seagull, Goshawk, and Rotax models.
| Identifier | WestWitteringFiles\J\November1922\ Scan116 | |
| Date | 29th November 1922 | |
| Contd. -2- EFC4/T29.11.22. The R.{Sir Henry Royce} Bosch machine works with an air gap no greater than .010" and the carcase is very massive, but the performance even for its weight is superior to all other machines. Part of the superiority is due to the use of tunnelled slots, straight sided teeth and a hand wound armature. The ampere turns for the pole core on the Seagull machine are quite easy, so that possibly a slight reduction in the field core might be an advantage in giving extra winding space. We should like to know if Mr. Royce considers that the limit of smallness of the air gap is entirely mechanical (prevention of fouling by magnetic drag), or whether it is not reduced owing to the reduction of field stiffness and consequent increase of control by armature reaction that would occur. If in the Seagull dynamo we have .015" air gap one would think we could comfortably arrange for .013" on the Goshawk machine and improve its performance accordingly. Speaking of the Goshawk dynamo we further attach a comparison of dimensions and weights of this machine with two others, viz., U.S.A. Bosch and Rotax, in which the dimensions and weights, with the exception of the carcase thickness, are almost identical. The best experimentally made Goshawk dynamo which we have has an output performance equal, or perhaps a little better than these other machines, all three just complying with our general specification of performance, but at the Contd. | ||