Ah, the days of old when men were bold and planes had round engines… And no electric starter. I got to fly with, and learn from, men and women of the Olde School, and they had more rituals than the Eastern Orthodox Church when it came to starting airplanes. Once I started working on vintage beasts, I learned why.
Round motors are sweet, amazing pieces of art and power when they work as desired. They are stone cold [invective of choice] when they don’t. And starting them is not as easy as the modern prime with gas, turn on magnetos, hit starter, add throttle and go. Oh no, no, one treated radial engines with the same delicate manners and techniques used for… Never mind, PG-13 blog. Anyway, crank and go is not a radial engine “thing.”
This is due in part to the basic design of radial engines. The cylinders are arranged in a circle around the crank-case, with the crank shaft and propeller shaft running through the center. Turbo-chargers and accessories are mounted behind and (often but not always) above the engine, or around the back. The oil drains out the bottom when you need to change it.
The first thing one does before starting a radial engine is rotate the propeller through by hand or using a very low-powered vehicle, IF the plane does not have an oil scavenging system, or you don’t trust said system. First, make darn certain that the ignition system is off, that the fuel is turned off, and that you are in a place where you will not get pulled into the propeller if it decides to “turn over” under its own power. Turn the prop through at least two full rotations. You want to make certain that no oil has accumulated in the bottom cylinders. Otherwise, when you add starter power to the engine, the piston will attempt to compress the oil instead of the gas vapors. This is known as hydraulic lock, and bends pistons, and can break the cylinder clean off the case. Mechanics and crew chiefs do not like this. Neither does the engine.
However, there was a time between the beginning of the large radial engine age and the perfection [waits for knowing laughter to stop] of the electric starter. This was the Age of the Inertial Starter, better known as the Armstrong Starter. No, not because of the name of the inventor. Nope, because of what it took to crank the starter hard enough to store sufficient energy to turn the engine and begin the ignition sequence.
Yes. Crank the starter. By hand, often while perched on the leading edge of the wing while the pilot did the two-handed starting ballet with switches and levers (throttle and mixture control) and stood on the brakes. Should a volunteer or other suitable victim not be found, the pilot adjusted things just so in the cockpit, set the brakes, made sure of the chocks, cranked the starter, then either ran around and climbed back in or leaned into the cockpit and started the engine, then ran around removing the chocks, jumped back in, stood on the brakes, and fastened his shoulder harness. Things went a bit more calmly after that. If it all worked. If the engine didn’t back-fire. If the brakes didn’t slip. If the chocks holding the wheels still did their job. If the engine didn’t decide to quit because the fuel-air mixture had gotten a little lean because the lever slipped, if…
Ah, the days of old, when men were bold, and engines a lot crankier than they are today. Although any piston engine needs some care when starting, and it is really easy to toast turbo-prop engines (and their starters) if you are not paying attention.