Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
I have no idea what that 6 bank 24 cylinder engine is
It's an Argus AS 5. I have a photo of that engine somewhere...
Argus As 5 Aircraft Engine | Old Machine Press
18 Cylinder Hispano intended for the Schneider cup.
Once V-12s made more power, there was no longer a need for W-18s. A Merlin-based W-18 would give you an engine too big to fit in a fighter, and for a bomber, why not use a R-2800 and do away with all that liquid-cooling stuff?
One would think a W-18 engine would offer 1/3 more power than a V-12 while maintaining a fairly compact package and relative light weight. But historically speaking for aircraft, W-18s have been a developmental dead end. At least, that is the way I see it.
Some problems might be more theoretical, but trying to get an even firing order? what angle/s between the banks gives an even firing order? Now try to get the cylinders to fire in a pattern that puts the least stress on the crankshaft.
Engine weight will not go up by 50% but there is more than adding just a cylinder bank as the crankcase and crankshaft will need to be heavier. Intake manifolding could be a real headache depending on country and design practice. Germans with fuel injection just have to worry about getting the same amount of air to each cylinder. Americans and British have to worry about the correct mixture to each cylinder. Italians and French can wind up with NINE carburetors to deal with. Then you have the exhaust manifolds. American, British and German V-12s were fairly neat, Intakes inside the V, exhausts outside. The W-18 needs an exhaust and intake sharing the same between banks space. Not as much of a problem for the French and Italians as they usually kept both th e intake and the exhaust on the outside of the V and shared space( the better to get at the carbs ?)
The "idea" behind the DB 606/610 (and the Allison V 3420 and a few others) was to use existing crankshafts/crank cases, conrods and just have to develop the reduction gears. Turns out that it was a bit more complicated than that but compared to developing all new bottom end parts?
The mixture distribution seem to be one of Vultures non-problematic things, that for 24 cylinders. How well it worked for the 3+ meter Chrysler V-2200, supercharger being at one end of the engine? Napier also got mixture distribution right for the 4-bank Sabre, again that being one of engine's non-problematic 'items'.
The W-18 needs a well executed exhaust of the mid bank, the side banks can do exhausts in classic layout.