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).
Condition of engine components and conclusions drawn from tests regarding oil pump performance.
| Identifier | ExFiles\Box 179b\3\ img086 | |
| Date | 1st January 1933 | |
| -4- This took the form of a strip about ½" wide, in the middle of the bearing and extended circumferentially for about 75% of the periphery in the case of No.3 and about 40% in the case of No.1. In addition there were a number of small high spots which were brightly polished in the cap half of No.1 bearing. The whitemetal on the outside of the big end bearing blocks was in normal condition. No.4 big end block upper half was fractured in the usual place. The pistons and cylinder bores had not suffered in any way. Conclusions. Although the tests did not produce a failure or even conclusive evidence of a potential failure, some invaluable information was obtained, namely :- (a) That the oil pump primes more rapidly with cold oil than with hot, and therefore pressure is gained more quickly in the former case. This point is of vital importance because it has been suggested that insufficient warming up was a contributory cause of failure. To increase the length of time of warming up would be most undesirable, in view of the conditions laid down in this direction, for the Day & Nighter fighter competition. (b) Since the pump primes more quickly with cold oil it is very probable the clearances in the oil pump will affect greatly the time required for it to reprime and in consequence the time necessary to restore oil pressure. It is to be expected therefore that individual engines will require times which differ considerably to regain oil pressure after rolling. (c) As apparently a core of air forms in the oil suction pipe in at least 10 secs. the time which an aircraft stays inverted will not affect materially the time taken to regain oil pressure. The bed tests confirmed this theory. (d) That evidence of potential failure was present, existed in the big end bearings in the front half of the engine. This is characteristic of the type of failure which we were trying to reproduce. | ||