he following answer is taken from Wardale’s response to Leonard Staghurst whose letter was published in Steam Railway #277 (copied below):
“Unfortunately Mr. Staghurst’s comments betray his lack of knowledge, not only of what is possible with steam traction but also of what has already been achieved. Consider the following.
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The above figures, which are amply supported by other data, show eloquently enough that the calculated power capacity of the 5AT is perfectly realistic, and I regard achieving it as a formality (and surpassing it a probability) – even on this planet! Likewise all factors concerning thermal efficiency, except the target combustion efficiency at maximum evaporation, which I have acknowledged will be a difficult problem. But that does not mean impossible, simply that very good engineering will be required to achieve it.”