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).
Letter from Vauxhall Motors discussing tyre data on cornering force, braking, and driving based on U.S. Rubber Company tests.
| Identifier | ExFiles\Box 170\3\ img146 | |
| Date | 21th January 1938 | |
| [Handwritten top left]: oy [Handwritten top right]: From m.s Vauxhall Motors Ltd CONTRACTORS TO THE ADMIRALTY, WAR OFFICE & AIR MINISTRY LUTON. BEDS. TELEPHONE NUMBER 2600 LUTON TELEGRAMS CARVOX. TELEX. LUTON WHEN REPLYING PLEASE QUOTE -> OUR REF: MD/KF YOUR REF: Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls}4/MH.{M. Huckerby} 21st January 1938. S.H. Grylls Esq., Rolls-Royce Limited, DERBY. Dear Gry{Shadwell Grylls} Replying to Ivan Waller's note of 5th January. Here are the facts on drive and overrun as shown in latest U.S. Rubber Company data Cornering Force. On a 6-16 4 ply tyre, inflation 28 lbs, load 915 lbs, 4.00 E rim, speed 25-30 m.p.h. 67" steel drum. 4° slip angle shows a cornering force of 375 lbs at .5 HP braking (practically free running). 393 lbs at 10 HP braking, 356 lbs at 13 HP driving. These figures are subject to an upward correction of approximately 10% for use on a flat surface. (Roughness and smoothness of surface makes little difference, so long as it's dry). So we should say for braking, a slight increase in cornering power; for driving a slight decrease. Just the opposite of what we thought. Attached Chart (No.5). It is necessary to show just exactly what the drag and cornering force on the U.S. tests are. They are not quite the same as Goodyear's. R.D. Evans at Goodyear measures cornering force square with the plane of the wheel and drag or rolling resistance in the plane of the wheel. U.S. measures cornering force square with the path of the wheel, and rolling resistance in the path of the wheel. So that an important component of Evans' cornering force exists in the drag figure obtained by U.S. | ||