This was taken from the website http://www.esparacing.com/Air%20Racing%20History/aircraft/Macchi-Castoli%20%20MC%2072.htm
In the difficult floating phase, torque absence should allow to have a balanced load on the floats: an important aspect, considering that, with 1800HP engine, the left float was loaded 23% more than right one. In 1931 Supermarine S-6B with 2650HP was 32% overloaded, while MC-72 barely reached 3% even with 3000HP. Behind this propeller stand a singular twin engine, obtained coupling on the same axle two 12V, 60 degrees engines directly derived from AS-5, each moving a propeller through two coaxial crankshafts passing through forward engine banks. Air intakes were in the centre, between both engines, while breathing system, composed by a centrifugal compressor and a bank of 8 aspirated carburettors, was single for the whole plant.
The plates “Front Engine” and “Back Engine”, still in the cockpit, show that semi-engines were independent, as confirmed by run-up scene in the famous movie of the record. It seemed the simplest solution, but, as often happens, AS-6 promises were harder to win than expected.
So from this, they were independently run but geared to the props together? :confused:
Cheers
TNZ
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