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 specifications for Packard and Wraith silencers.
| Identifier | ExFiles\Box 152\3\ scan0197 | |
| Date | 21th September 1937 guessed | |
| 1297 9 PACKARD SILENCER. WRAITH SILENCER. WEIGHT 60 lbs. WEIGHT 105 lbs. ------------------------------------------------------------------------------------------------------ Size Area Gauge. | Size Area Gauge. Front Expn. Box. - - - | 18" x 4" 72 sq.in. 16 = .064". Front Silencer. 28" x 7½" 210 sq.in. 22 = .028" | 17" x 6½" 106 sq.in. 16 = .064". Rear Silencer 20" x 6" 120 sq.in. 22 = .028" | 22½" x 6½" 140 sq.in. 16 = .064". 330 sq.in. | 318 sq.in. Inner pipe of } Dia. 2.625" 18 = .048". | Dia. 2.00 16 = .064". front silencer. } Inner pipe of } Dia. 2.125. 22 = .028". | Dia. 2.00. 16 = .064". rear silencer. } Downtake pipe Dia. 2.50" 17 = .056". | Dia. 2.00 16 = .064". Intermediate pipe Dia. 2.25" 17 = .056". | Dia. 2.00 16 = .064". Tail pipe Dia. 2.125". 17 = .056". | Dia. 1.50". 16 = .064". | ||