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).
Contributing factors to valve bounce in F.10 engines.
| Identifier | ExFiles\Box 43\3\ Scan105 | |
| Date | 1st January 1927 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/ACL. 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} V4003 Hs{Lord Ernest Hives - Chair}/ACL1/LG4.1.27. F.10. VALVE BOUNCE. /3822 Considering the question of valve bounce on the F.10. and going over some of the tests which have yielded information, we think that although no doubt the gas velocity past the inlet valve accounts for part of the difference observed between its action and that of the exhaust valve it does not completely supply the difference. The duration of lift for the inlet is less than for the exhaust valve and results in the acceleration required from the spring being greater than for the exhaust valve at the same speed. At an engine speed of 2400 r.p.m. the deceleration required during the lift period and acceleration during the closing period for the inlet cam is 1651.8 ft/sec/sec. while for the exhaust it is 1297.8 ft/sec/sec. The equivalent reciprocating weight of one inlet valve, rocker, etc. is .506 lbs. and .517 lbs. for the exhaust. The acceleration required varies as the square of the speed and directly as the reciprocating weight, therefore on this assumption we should not expect the exhaust valve to leave the cam until approximately 10% higher speed than that at which the inlet started. Another factor is that probably the exhaust valve is assisted in closing by the expelled gases. Contd. | ||