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).
Graph comparing Torque versus Angular Deflection for Standard Hardy and Alpe couplings.
| Identifier | ExFiles\Box 65\4\ scan0097 | |
| Date | 9th October 1928 guessed | |
| TORQUE LBS/FT 700 600 500 400 300 200 100 STANDARD HARDY COUPLING APPROX. MAX ENGINE TORQUE ALPE COUPLING ANGULAR DEFLECTION DEGREES 1° 2° 3° 4° 5° 6° 7° 8° 9° 10° | ||