Hi,
The DQ had cross-compound engines, with different cylinder diameters, and the different dimensions on the drawings imply they also had different strokes.
However the DQ web-site referenced in a previous post states they both had 10 foot strokes.
It would not surprise me that the cross-compound engines also had different strokes. Hence different crank lengths.
The paddle shaft acts as the crank shaft, turning the two engines into one.
If the drawings are to 1:100 scale, then this imply's one stroke was 10'-0" and the other 15'-0".
Further research required me thinks
cheers
kiwi