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).
3-litre compression ignition unit's specifications and suitability for a Phantom engine.
| Identifier | WestWitteringFiles\T\March1929-December1929\ Scan318 | |
| Date | 28th December 1929 guessed | |
| (2) ORIGINAL. The compression ignition unit is of 3 litre capacity, and at 2500 RPM. will require about 150 c. ft/min. of air for 50% supercharge, so that this particular blower would have to be geared at half engine speed. This model as a matter of fact is said to be the right size for an engine of Phantom dimensions, on which a 50% supercharge would require about 350 c. ft. per min. of free air at 2500 RPM. The provision for mounting a coupling for driving the blower consists of a parallel .812 dia. shaft with Woodruff and nut. This would not we think be satisfactory eventually, especially in view of the considerable flywheel effect of the revolving steel cage on which the edges of the vanes slide. There is apparently not much seal at the driving end as a considerable escape of air is felt at this point when turning the rotor by hand with delivery shut off. The weight of this model is 58 lbs., and reckoning on 225HP. from a supercharged engine of Phantom size, this would be roughly .25 lbs. per BHP., or approximately twice the weight per HP. for the RR. F.{Mr Friese} centrifugal blower and drive. We are forwarding the blower to Derby immediately after Xmas and arranging for the scheme for the drive on the compression ignition unit unless we hear that you do not approve of the use of this machine for the purpose. E.{Mr Elliott - Chief Engineer} | ||