Calculated Performance Predictions for the 5AT

5AT Performance Predictions defined in Wardale’s FDCs

The “Deltic” performance predictions for the 80 tonne 5AT locomotive are astonishing when compared to similar sized locomotives of the “steam era”. It is hard to believe that a locomotive no bigger than a Standard Class 5 would be able to produce performances far superior to any British Pacifics of the steam era. Yet such predictions are based both on detailed engineering calculations and on the actual performance of “The Red Devil“, the sole member of the SAR Class 26 4-8-4 locomotive, as modified by David Wardale in the 1980s using the theories and practices developed by Ing. L.D. Porta in Argentina.

The calculations on which the performance predictions for the 5AT are based are referred to as the “Fundamental Design Calculations” or FDCs and were undertaken by David Wardale during 2002-2004, of which Part 1 is presented on this website. These calculations are split up into five sections:

See also Wardale’s chart comparing the Power-Weight ratios between the 5AT and various other well locomotives and diesel/electric multiple units.