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).
Summary of investigations into the results of armoured car tests, detailing weights, gradients, and performance calculations.
| Identifier | ExFiles\Box 182\M21\ img078 | |
| Date | 27th June 1921 | |
| To R.{Sir Henry Royce} from DA.{Bernard Day - Chassis Design} -4- DA{Bernard Day - Chassis Design}5/G27/6/21 Contd. SUMMARY OF INVESTIGATIONS INTO RESULTS OF ARMOURED CAR TESTS. The weights and gradients given on the actual trials are rather uncertain. The following are stated, but Mr. Maddocks has promised to send actual figures:- With 9688 lbs. gross load, car failed on 1 in 4 and 1 in 5.9 with both 38" and 40" wheels. With 8904 lbs. car with 38" wheels climbed 1 in 5.9 and with 7864 lbs. climbed 1 in 4. The following are facts of possible performances. Gear ratio - 1st speed - 13.18 / 2.62 M.E.P. (at road wheels) which occurs at speeds which are possible in climbing on 1st. gear - 73.5 lbs. sq.ins. average (low compression) (The M.E.P. is the true basis for judging or comparing performance) (1) The maximum gradient which the cars will climb with 9688 lbs. load is - 38" wheels - 1 in 5.94 40" wheels - 1 in 6.30 (2) Climbing 1 in 5.9 with 8904 lbs and 38" wheels M.E.P. = 85.2 lbs. sq.inc. (shewing that car could have done better) 71.2 (3) Climbing 1 in 4 with 7864 lbs. and 38" wheels M.E.P. = 80.3 lbs. sq.ins. (shewing this performance to be impossible.) 89.8 (4) If the weight carried up 1 in 4 with 38" wheels were 7056 lbs (as may have been the fact) M.E.P. = 76.5 lbs. sq.ins. (which would be possible with a very good engine above the average) (5) As arranged at present the maximum weight which these cars can carry up the gradient of 1 in 4 is - 38" wheels - 6770 lbs. (these exact weights will, of 40" wheels. - 6430 lbs. course vary if the wheel dia- (meters are not exact, and if (the enquiries are above or (below the average.) (6) There are two statements made with reference to our cars which may be tested by this method for comparison - (Contd.) | ||