Man I just realized I haven't posted in years. But anyhow I used to ask my Father about radial vs. inline or V configuration engines when I was a kid because of the FW-190 changing from a radial to inline in the Dora model. The differences and advantages are many between the two, including power and torque curves, reliability, ect. that were mentioned previously in this thread.
As far as power goes, the inline initially had less torque and power due to packaging constraints with the inline engines, but eventually as designs and technology change, the inlines have obviously proven to be a more compact, and solution that had far surpassed the radials regarding tunability (the 109's were inverted with bosch fuel injection....amazing that was in the late '30s).
The one thing to think about that made it clear as day regarding reliabilty is this. When people mention radials being air cooled and inline engines being water cooled I used to think of the coolant lines and radiator as risky components for targets or failure, which they were, but the engine blocks themselves were the saviors. Just as hydrolic systems had backups, many planes included duel radiators and the ability to shut off one if one was damaged or destroyed to delay the coolant from draining from the engine.
What I didn't grasp at first is think of the actual engine packaging. The engine being the front of the aircraft increased its potential for a direct hit from head-on fire. A radial is packaged with the cylinders in a radial design around the centerline and seperated for air to cool inbetween them but also spacing them far apart. They can and often did take a direct hit to one cylinder, and still have little effect on the rest of the engine, even the oiling system. Many lost cylinders completely and still made in back. An inline engine due to its nature of design surrounding all cylinders with coolant and the oiling system throughout the block can not take any amount of direct block damage without catastrophic failure of the entire engine. Its quite a huge difference in ease of maintanance and design realiability based on simplicity and basic design parameters that give the radials quite an advantage going into battle in WWII. The aerodynamic limitations as well as oiling and tunability, and ultimate power limitations (late war) were the reasons for the change to inline designs. Just my two cents regarding the intitial topic. I still thing of my Father and this topic whenever I see a large radial designed plane.
