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 the construction differences between Bosch and Lucas horns, focusing on the disc, base, and mounting.
| Identifier | ExFiles\Box 59\3\ Scan073 | |
| Date | 30th September 1930 guessed | |
| -3- The Bosch disc is made of aluminium plate, the Lucas is cast and has two 3/16" holes 1 1/4" apart on either side of the centre which must almost certainly affect air flow. The shapes of the surrounding throats on the two horns are also different. The main base of the Lucas instrument is a heavy iron casting, whereas the Bosch is a pressing. If an iron mass be held firmly against the Bosch base the note produced suffers a deadening effect somewhat like the Lucas. It is evidently the purpose of the laminated mounting bracket to avoid this deadening effect of large masses on the main body of the horn. We think attention to these points, especially the last, gives the best promise of getting approximately the note we require. RJA. | ||