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).
Investigation into a 'booming' noise, concluding it is a body or frame characteristic.
| Identifier | WestWitteringFiles\V\March1931-September1931\ Scan174 | |
| Date | 7th May 1931 | |
| ORIGINAL SC. LHS.{Lord Herbert Scott}) FROM R.{Sir Henry Royce} RM.{William Robotham - Chief Engineer} R8/M7.5.31 C. to WOR.{Arthur Wormald - General Works Manager} HS.{Lord Ernest Hives - Chair}-E C. to DAY EP{G. Eric Platford - Chief Quality Engineer} P. 2. BOOMING. 8634. x7830. Last Thursday - April 30. - we had much discussion on the above, with the following result: It will be remembered that I was anxious to find the periodicity of the boom. This is now pretty certainly settled at 6600 per minute. It has been found to be a period independent of the power unit, by using other means of producing vibrations of different periodicity until the body responded (by R's electro motor test) and Derby's road tests (pave setts) and tyre studs. So then this booming at 50/60 MPH. must be a body or frame characteristic, (not a power unit characteristic.) True the engine does excite it, as does an electro motor with very, very, slight out of balance, and we now know the incurable characteristic of piston inertia vibration is the cause, as these coincide at 6600 perminute at 2200 engine revs. Fortunately the engine can be insulated from commuting these torsion impulses to the frame, as was done fairly well on P. 1. and less perfectly on P. 2., and will be still better on P. 2. converted. The actual feature which decides the periodicity of the booms may be the sound wave between floor and roof, or it may be the stiffness of the frame: this is being investigated. R.{Sir Henry Royce} | ||