J.A.W. wrote: ↑
Sun Apr 30, 2017 1:27 am
Indeed it seems a bit difficult to discern, even for the period technical reviewers..
I have read reports that emphatically state that twin-fire was avoided in the Sabre,
& others that claim it was expected given the phasing - to get individual firing, from
24 4T cylinders it would be one firing every 30`of phased twin 12 cyl crank rotation..
They could have but it would require the crankshaft to be phased at 30° as you said. Or 90°.
One reason why they phased the cranks together may have been to maximize clearance between the two cranks. If they were 180° apart the crank throws would be closer together at one point in their rotation. By being in phase they avoid that issue, potentially being able to bring the cranks closer.
If the cranks were counter-rotating it might work such that the crank throws are like meshing gears.
I think the phasing decision was also down to the design and layout of the sleeves and sleeve drives. By phasing them together the sleeve drives were simplified.