Air cooled inline engines - a missed opportunity?

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Getting back to the inline air cooled engines, the limits are set by the amount of power you can get out of one cylinder and then how do you arrange the needed number of cylinders.
The Dagger made 41.6hp per cylinder.
The P & W R-1830 makes about 75hp per cylinder at altitude on 100 octane (not 100/130) fuel.
An early R-2800 makes about 83.3hp per cylinder at 14,000ft (1500hp)

Kind of obvious that a V-12 won't give the needed power so now we start looking at 16 cylinder engines, either X or H or 24 cylinder engines again either X or H.
An X engine is going to have about the same diameter as a radial although you can flatten the top/bottom/sides a bit.
The H is going to have two crankshafts and is probably going to be heavier.
Inline air cooled engines are going to be longer than a liquid cooled engine of the same size cylinders because you have to space the cylinders further apart for fins and air flow.
The longer engine needs to be heavier for strength in addition to just for the size.

Every significant change in power on a radial engine came with a change in cooling, not just changing the fuel and increasing the boost.
A cutaway R-2800

This shows the cylinder spacing between the rows (and there is a slight overlap) and the amount of fin depth needed.
Also the size of the heads and the fins needed to keep the head cooled. Yes there are rocker boxes but they are individual boxes and long cam boxes or cam and rocker box covers used by V-12s.

Overhead cam (or cams) running between the valves and with rockers covering the head?
This works on lower powered engines. Not so good on high power (high heat transfer) engines.

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