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).
Blueprint of a PTT exhaust system with small diameter pipes.
| Identifier | ExFiles\Box 14\6\ Scan232 | |
| Date | 27th November 1931 | |
| Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}/27/11/31, SPECIAL MANIFOLD TO SUIT 2" DOWNTAKE, ALL PIPES 2 1/4" INSIDE DIA, .125 THICK., SILENCER TO Hs{Lord Ernest Hives - Chair} 476, EXISTING FRONT EXPANSION BOX WITH DOWN PIPE LEAD IN AT THE END., PTT EXHAUST SYSTEM WITH SMALL DIA PIPES | ||