Engine Cylinders & Firing Function
Thank you for your replies. I understand the physics of a 4 stroke power delivery and the generated crankshaft pulsations in the operation of a radial engine and your good postings cemented my understanding of "odd cylinder requirements."
Though not mentioned specifically, it seems the considerations that apply to cylinder number and arrangement in a radial engine would also be a factor in the sixty degree cylinders of a V-6 & V-12 engine as opposed to ninety degrees for an 8 cylinder engine. Thank you both very much for the answers.
Interestingly, there was also the Allison V-3420,a 24 cylinder engine that was essentially, two V-1710s mated together, designed for the General Motors P-75 Eagle. It was built with its calling specifically for contra-rotating propellers (on the P-75) and was "cutting edge technology." It had been scheduled for the Lockheed XP-58 Chain Lightning but problems shelved it with the completion of one prototype. It seems our engineers surpassed the Germans on this one.
These aircraft were put forward to fill a need for a fast-climbing and high-flying aircraft to escort bombers in Europe. They were both dropped of course when the tides of war began turning against the Germans and in the Pacific, our B-29s were able to conduct missions unescorted because of their speed and operational altitude made interception almost impossible. Also the P-51 nicely filled the escort role in Europe once it was mated with the Packard license-built Merlin. It is a very interesting concept to read about and fortunately, literature about them exists and is available on the internet.