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).
Data table showing forward and reverse steering efficiency calculations.
| Identifier | ExFiles\Box 28\2\ Scan163 | |
| Date | 28th March 1933 guessed | |
| -2- "FORWARD EFFICIENCY" Drop arm radius - 8" Radius of application of steering wheel load - 7 3/8" Velocity ratio - 10.9/1. Load on Drop Arm (lbs) | Load on Steering Wheel Arm (lbs) | Drop Arm Torque (lbs.ins) | Steering Wheel Torque (lbs.ins) | Efficiency. % 50 | 8.88 | 400 | 67.8 | 54.2 100 | 16.75 | 800 | 127.6 | 57.6 150 | 24.88 | 1200 | 190.0 | 58.0 200 | 33.13 | 1600 | 252.0 | 58.3 250 | 41.50 | 2000 | 316.0 | 58.1 300 | 49.75 | 2400 | 379.0 | 58.1 350 | 59.00 | 2800 | 450.0 | 57.2 "REVERSE EFFICIENCY" 50 | 0.88 | 400 | 6.71 | 18.3 100 | 3.25 | 800 | 24.80 | 33.8 150 | 5.50 | 1200 | 42.00 | 38.2 200 | 7.75 | 1600 | 59.00 | 40.2 250 | 9.75 | 2000 | 74.30 | 40.5 300 | 11.50 | 2400 | 87.60 | 39.8 350 | 14.00 | 2800 | 107.00 | 41.7 | ||