Redesign modifications for weight reduction on the E.XVI direct drive nose.
| Identifier | ExFiles\Box 42\1\ Scan139 | |
| Date | 25th February 1926 | |
| TO R. {Sir Henry Royce} & BY. {R.W. Bailey - Chief Engineer} FROM AJS. Copy to CJ. B. RG. {Mr Rowledge} HS. {Lord Ernest Hives - Chair} ORIGINAL X3829 AJS1/M25.2.26. re. LIGHTENED RR. E.XVI. DIRECT DRIVE NOSE. X3829 With reference to your instructions received through E. {Mr Elliott - Chief Engineer} for lightening the above unit, and which was referred to in AJS1/M11226., we now send herewith drawing LeC. 2202. (original to BY. {R.W. Bailey - Chief Engineer} print to R. {Sir Henry Royce} ) shewing a redesign of the above unit for reducing weight. The features making for lightening that have been incorporated are:- (1) THRUST BEARING. This has been reduced to the next size smaller N.D. bearing No.214. of same type, and has one less ball per row, but the same size balls as No.215. previously used, in which the thrust capacity appeared to be more than 3 times the Air Board requirements so far as duration of test was concerned. We have asked HS. {Lord Ernest Hives - Chair} to test a No.214. bearing. (2) SHAFT. We understood you had considered the torque due to gyroscopic action due to zooming which was calculated for the engine supports to be unduly severe and probably not experienced in practice. We have therefore in the calculations for the shaft halved the original figure for this, and added 1000 in. lbs. bending moment due to propeller weight, the torsion remaining as before. Although we have reduced the outside dia. of the shaft at the thrust bearing by 5 mm., and elsewhere in proportion, and increased the bore by .050, the halving of the torque just referred to has in this case brought the maximum shear skin stress to round about 24,000., which appears low when not considered in conjunction with the probable now low value of the gyroscopic torque. (3) FLOATING BUSH JOURNAL BEARING. This has been reduced in area and its housing is now a comparatively light steel bush carried in the aluminium extension in place of the comparatively large and steel flanged housing originally used. We consider that if the steel bush is a fit of from 3½ to 4½ thous. tight on the dia., it will never get loose due to normal bearing temperatures, and the aluminium will not be stressed beyond the elastic limit. (1) | ||
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).