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).
The performance characteristics of a Falcon X supercharger, detailing inefficiencies in the diffuser and inlet guide vanes.
| Identifier | ExFiles\Box 42\3\ Scan046 | |
| Date | 1st December 1926 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/AR. c. to BJ. Wor.{Arthur Wormald - General Works Manager} c. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c. to BY.{R.W. Bailey - Chief Engineer} AJS. VS{J. Vickers}8241 Hs{Lord Ernest Hives - Chair}/ARL/LG4.12.26. FALCON X, SUPERCHARGER. K4550 We give herewith set of characteristics for the supercharger with modified rotor and diffuser vane angles at 20,000 and 18,000 r.p.m. We are taking a further set at 22,500 r.p.m. The supercharger is geared up 10/1, so that 22,500 r.p.m. corresponds to normal engine speed, but we would point out that to give the designed tip speed of 310 ft/sec. the super-charger r.p.m. should be 20,600 r.p.m. The maximum efficiencies obtained are still low. We think there are two main reasons for this. (1) The six diffuser vanes are so proportioned that their venturi action is inefficient. (2) Inlet guide vane angles require modification. (1) Diffuser. We think that the angle of the diffuser vanes is now correct to give max. efficiency at the designed delivery of the supercharger. On our testing rig, maximum efficiency occurs at a delivery of 49 lbs/min., this is lower than the designed figure of 56 lbs/min. since the rig only produces pressure, and not temperature conditions corresponding to a given altitude, giving a slightly lower density at the rotor circumference than would be actually obtained. We [strikethrough]also[/strikethrough] found that we could not make the diffuser contd :- | ||